kc3-lang/libtommath

diff --git a/.travis.yml b/.travis.yml
index a6a097d..358f03c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -112,7 +112,8 @@ matrix:
             - gcc-4.9
 
     # clang for x86-64 architecture (64-bit longs and 64-bit pointers)
-    - env: SANITIZER=1 CONV_WARNINGS=1 BUILDOPTIONS='--with-cc=clang-7 --with-m64 --with-valgrind'
+    - env: SANITIZER=1 CONV_WARNINGS=strict BUILDOPTIONS='--with-cc=clang-7 --with-m64 --with-valgrind'
+    - env: SANITIZER=1 CONV_WARNINGS=relaxed BUILDOPTIONS='--with-cc=clang-7 --with-m64 --with-valgrind'
     - env: SANITIZER=1 BUILDOPTIONS='--with-cc=clang-6.0 --with-m64 --with-valgrind'
       addons:
         apt:
diff --git a/bn_deprecated.c b/bn_deprecated.c
index 7a20583..5dc3da9 100644
--- a/bn_deprecated.c
+++ b/bn_deprecated.c
@@ -7,73 +7,73 @@
 /* SPDX-License-Identifier: Unlicense */
 #include <tommath_private.h>
 #ifdef BN_FAST_MP_INVMOD_C
-int fast_mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err fast_mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
 {
    return s_mp_invmod_fast(a, b, c);
 }
 #endif
 #ifdef BN_FAST_MP_MONTGOMERY_REDUCE_C
-int fast_mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho)
+mp_err fast_mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho)
 {
    return s_mp_montgomery_reduce_fast(x, n, rho);
 }
 #endif
 #ifdef BN_FAST_S_MP_MUL_DIGS_C
-int fast_s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err fast_s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
    return s_mp_mul_digs_fast(a, b, c, digs);
 }
 #endif
 #ifdef BN_FAST_S_MP_MUL_HIGH_DIGS_C
-int fast_s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err fast_s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
    return s_mp_mul_high_digs_fast(a, b, c, digs);
 }
 #endif
 #ifdef BN_FAST_S_MP_SQR_C
-int fast_s_mp_sqr(const mp_int *a, mp_int *b)
+mp_err fast_s_mp_sqr(const mp_int *a, mp_int *b)
 {
    return s_mp_sqr_fast(a, b);
 }
 #endif
 #ifdef BN_MP_BALANCE_MUL_C
-int mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
    return s_mp_balance_mul(a, b, c);
 }
 #endif
 #ifdef BN_MP_EXPTMOD_FAST_C
-int mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
+mp_err mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
 {
    return s_mp_exptmod_fast(G, X, P, Y, redmode);
 }
 #endif
 #ifdef BN_MP_INVMOD_SLOW_C
-int mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c)
 {
    return s_mp_invmod_slow(a, b, c);
 }
 #endif
 #ifdef BN_MP_KARATSUBA_MUL_C
-int mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
    return s_mp_karatsuba_mul(a, b, c);
 }
 #endif
 #ifdef BN_MP_KARATSUBA_SQR_C
-int mp_karatsuba_sqr(const mp_int *a, mp_int *b)
+mp_err mp_karatsuba_sqr(const mp_int *a, mp_int *b)
 {
    return s_mp_karatsuba_sqr(a, b);
 }
 #endif
 #ifdef BN_MP_TOOM_MUL_C
-int mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
    return s_mp_toom_mul(a, b, c);
 }
 #endif
 #ifdef BN_MP_TOOM_SQR_C
-int mp_toom_sqr(const mp_int *a, mp_int *b)
+mp_err mp_toom_sqr(const mp_int *a, mp_int *b)
 {
    return s_mp_toom_sqr(a, b);
 }
diff --git a/bn_mp_2expt.c b/bn_mp_2expt.c
index 2b669da..993b4e3 100644
--- a/bn_mp_2expt.c
+++ b/bn_mp_2expt.c
@@ -8,9 +8,9 @@
  * Simple algorithm which zeroes the int, grows it then just sets one bit
  * as required.
  */
-int mp_2expt(mp_int *a, int b)
+mp_err mp_2expt(mp_int *a, int b)
 {
-   int     res;
+   mp_err    res;
 
    /* zero a as per default */
    mp_zero(a);
diff --git a/bn_mp_abs.c b/bn_mp_abs.c
index 8e6855f..f2b0526 100644
--- a/bn_mp_abs.c
+++ b/bn_mp_abs.c
@@ -7,9 +7,9 @@
  *
  * Simple function copies the input and fixes the sign to positive
  */
-int mp_abs(const mp_int *a, mp_int *b)
+mp_err mp_abs(const mp_int *a, mp_int *b)
 {
-   int     res;
+   mp_err     res;
 
    /* copy a to b */
    if (a != b) {
diff --git a/bn_mp_add.c b/bn_mp_add.c
index dab0820..1ded200 100644
--- a/bn_mp_add.c
+++ b/bn_mp_add.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* high level addition (handles signs) */
-int mp_add(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     sa, sb, res;
+   mp_sign sa, sb;
+   mp_err res;
 
    /* get sign of both inputs */
    sa = a->sign;
diff --git a/bn_mp_add_d.c b/bn_mp_add_d.c
index c02cb4e..f96674b 100644
--- a/bn_mp_add_d.c
+++ b/bn_mp_add_d.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* single digit addition */
-int mp_add_d(const mp_int *a, mp_digit b, mp_int *c)
+mp_err mp_add_d(const mp_int *a, mp_digit b, mp_int *c)
 {
-   int     res, ix, oldused;
+   mp_err     res;
+   int ix, oldused;
    mp_digit *tmpa, *tmpc, mu;
 
    /* grow c as required */
diff --git a/bn_mp_addmod.c b/bn_mp_addmod.c
index 72b5720..9205b1c 100644
--- a/bn_mp_addmod.c
+++ b/bn_mp_addmod.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* d = a + b (mod c) */
-int mp_addmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
+mp_err mp_addmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
 {
-   int     res;
+   mp_err  res;
    mp_int  t;
 
    if ((res = mp_init(&t)) != MP_OKAY) {
diff --git a/bn_mp_and.c b/bn_mp_and.c
index 78e42d9..cca5ca8 100644
--- a/bn_mp_and.c
+++ b/bn_mp_and.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* AND two ints together */
-int mp_and(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_and(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res, ix, px;
+   int ix, px;
+   mp_err res;
    mp_int  t;
    const mp_int *x;
 
diff --git a/bn_mp_cmp.c b/bn_mp_cmp.c
index 6fd9371..ced4840 100644
--- a/bn_mp_cmp.c
+++ b/bn_mp_cmp.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* compare two ints (signed)*/
-int mp_cmp(const mp_int *a, const mp_int *b)
+mp_ord mp_cmp(const mp_int *a, const mp_int *b)
 {
    /* compare based on sign */
    if (a->sign != b->sign) {
diff --git a/bn_mp_cmp_d.c b/bn_mp_cmp_d.c
index f0aa507..5a8337b 100644
--- a/bn_mp_cmp_d.c
+++ b/bn_mp_cmp_d.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* compare a digit */
-int mp_cmp_d(const mp_int *a, mp_digit b)
+mp_ord mp_cmp_d(const mp_int *a, mp_digit b)
 {
    /* compare based on sign */
    if (a->sign == MP_NEG) {
diff --git a/bn_mp_cmp_mag.c b/bn_mp_cmp_mag.c
index 482cef5..315a826 100644
--- a/bn_mp_cmp_mag.c
+++ b/bn_mp_cmp_mag.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* compare maginitude of two ints (unsigned) */
-int mp_cmp_mag(const mp_int *a, const mp_int *b)
+mp_ord mp_cmp_mag(const mp_int *a, const mp_int *b)
 {
    int     n;
    mp_digit *tmpa, *tmpb;
diff --git a/bn_mp_complement.c b/bn_mp_complement.c
index 7fab918..3a71adb 100644
--- a/bn_mp_complement.c
+++ b/bn_mp_complement.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* b = ~a */
-int mp_complement(const mp_int *a, mp_int *b)
+mp_err mp_complement(const mp_int *a, mp_int *b)
 {
-   int res = mp_neg(a, b);
+   mp_err res = mp_neg(a, b);
    return (res == MP_OKAY) ? mp_sub_d(b, 1uL, b) : res;
 }
 #endif
diff --git a/bn_mp_copy.c b/bn_mp_copy.c
index 19fa9dc..9e023bb 100644
--- a/bn_mp_copy.c
+++ b/bn_mp_copy.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* copy, b = a */
-int mp_copy(const mp_int *a, mp_int *b)
+mp_err mp_copy(const mp_int *a, mp_int *b)
 {
-   int     res, n;
+   int n;
+   mp_err res;
 
    /* if dst == src do nothing */
    if (a == b) {
diff --git a/bn_mp_decr.c b/bn_mp_decr.c
index 7bd248d..2e85ecb 100644
--- a/bn_mp_decr.c
+++ b/bn_mp_decr.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* Decrement "a" by one like "a--". Changes input! */
-int mp_decr(mp_int *a)
+mp_err mp_decr(mp_int *a)
 {
-   int e = MP_OKAY;
+   mp_err e = MP_OKAY;
    if (MP_IS_ZERO(a)) {
       mp_set(a,1uL);
       a->sign = MP_NEG;
diff --git a/bn_mp_div.c b/bn_mp_div.c
index 53a342e..9bd80ea 100644
--- a/bn_mp_div.c
+++ b/bn_mp_div.c
@@ -6,10 +6,11 @@
 #ifdef BN_MP_DIV_SMALL
 
 /* slower bit-bang division... also smaller */
-int mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
+mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
 {
    mp_int ta, tb, tq, q;
-   int    res, n, n2;
+   int     n, n2;
+   mp_err res;
 
    /* is divisor zero ? */
    if (MP_IS_ZERO(b)) {
@@ -88,10 +89,12 @@ LBL_ERR:
  * The overall algorithm is as described as
  * 14.20 from HAC but fixed to treat these cases.
 */
-int mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
+mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
 {
    mp_int  q, x, y, t1, t2;
-   int     res, n, t, i, norm, neg;
+   int     n, t, i, norm;
+   mp_sign neg;
+   mp_err  res;
 
    /* is divisor zero ? */
    if (MP_IS_ZERO(b)) {
diff --git a/bn_mp_div_2.c b/bn_mp_div_2.c
index 7935235..a51510b 100644
--- a/bn_mp_div_2.c
+++ b/bn_mp_div_2.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* b = a/2 */
-int mp_div_2(const mp_int *a, mp_int *b)
+mp_err mp_div_2(const mp_int *a, mp_int *b)
 {
-   int     x, res, oldused;
+   int     x, oldused;
+   mp_err res;
 
    /* copy */
    if (b->alloc < a->used) {
diff --git a/bn_mp_div_2d.c b/bn_mp_div_2d.c
index e13c471..d8c2377 100644
--- a/bn_mp_div_2d.c
+++ b/bn_mp_div_2d.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* shift right by a certain bit count (store quotient in c, optional remainder in d) */
-int mp_div_2d(const mp_int *a, int b, mp_int *c, mp_int *d)
+mp_err mp_div_2d(const mp_int *a, int b, mp_int *c, mp_int *d)
 {
    mp_digit D, r, rr;
-   int     x, res;
+   int     x;
+   mp_err res;
 
    /* if the shift count is <= 0 then we do no work */
    if (b <= 0) {
diff --git a/bn_mp_div_3.c b/bn_mp_div_3.c
index ccd8e85..bfa5710 100644
--- a/bn_mp_div_3.c
+++ b/bn_mp_div_3.c
@@ -4,12 +4,13 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* divide by three (based on routine from MPI and the GMP manual) */
-int mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
+mp_err mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
 {
    mp_int   q;
    mp_word  w, t;
    mp_digit b;
-   int      res, ix;
+   mp_err   res;
+   int      ix;
 
    /* b = 2**MP_DIGIT_BIT / 3 */
    b = ((mp_word)1 << (mp_word)MP_DIGIT_BIT) / (mp_word)3;
diff --git a/bn_mp_div_d.c b/bn_mp_div_d.c
index c75e170..fcfe36a 100644
--- a/bn_mp_div_d.c
+++ b/bn_mp_div_d.c
@@ -22,12 +22,13 @@ static int s_is_power_of_two(mp_digit b, int *p)
 }
 
 /* single digit division (based on routine from MPI) */
-int mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d)
+mp_err mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d)
 {
    mp_int  q;
    mp_word w;
    mp_digit t;
-   int     res, ix;
+   mp_err res;
+   int ix;
 
    /* cannot divide by zero */
    if (b == 0u) {
diff --git a/bn_mp_dr_is_modulus.c b/bn_mp_dr_is_modulus.c
index d59940f..83760ea 100644
--- a/bn_mp_dr_is_modulus.c
+++ b/bn_mp_dr_is_modulus.c
@@ -4,13 +4,13 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* determines if a number is a valid DR modulus */
-int mp_dr_is_modulus(const mp_int *a)
+mp_bool mp_dr_is_modulus(const mp_int *a)
 {
    int ix;
 
    /* must be at least two digits */
    if (a->used < 2) {
-      return 0;
+      return MP_NO;
    }
 
    /* must be of the form b**k - a [a <= b] so all
@@ -18,10 +18,10 @@ int mp_dr_is_modulus(const mp_int *a)
     */
    for (ix = 1; ix < a->used; ix++) {
       if (a->dp[ix] != MP_MASK) {
-         return 0;
+         return MP_NO;
       }
    }
-   return 1;
+   return MP_YES;
 }
 
 #endif
diff --git a/bn_mp_dr_reduce.c b/bn_mp_dr_reduce.c
index 25b7b15..ffc33a6 100644
--- a/bn_mp_dr_reduce.c
+++ b/bn_mp_dr_reduce.c
@@ -17,9 +17,10 @@
  *
  * Input x must be in the range 0 <= x <= (n-1)**2
  */
-int mp_dr_reduce(mp_int *x, const mp_int *n, mp_digit k)
+mp_err mp_dr_reduce(mp_int *x, const mp_int *n, mp_digit k)
 {
-   int      err, i, m;
+   mp_err      err;
+   int i, m;
    mp_word  r;
    mp_digit mu, *tmpx1, *tmpx2;
 
diff --git a/bn_mp_error_to_string.c b/bn_mp_error_to_string.c
index 97b35ae..e936ec1 100644
--- a/bn_mp_error_to_string.c
+++ b/bn_mp_error_to_string.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* return a char * string for a given code */
-const char *mp_error_to_string(int code)
+const char *mp_error_to_string(mp_err code)
 {
    switch (code) {
    case MP_OKAY:
diff --git a/bn_mp_export.c b/bn_mp_export.c
index 2167e89..5c8a492 100644
--- a/bn_mp_export.c
+++ b/bn_mp_export.c
@@ -6,10 +6,10 @@
 /* based on gmp's mpz_export.
  * see http://gmplib.org/manual/Integer-Import-and-Export.html
  */
-int mp_export(void *rop, size_t *countp, int order, size_t size,
-              int endian, size_t nails, const mp_int *op)
+mp_err mp_export(void *rop, size_t *countp, int order, size_t size,
+                 int endian, size_t nails, const mp_int *op)
 {
-   int result;
+   mp_err result;
    size_t odd_nails, nail_bytes, i, j, bits, count;
    unsigned char odd_nail_mask;
 
diff --git a/bn_mp_expt_d.c b/bn_mp_expt_d.c
index b2921ea..41a7cbe 100644
--- a/bn_mp_expt_d.c
+++ b/bn_mp_expt_d.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* wrapper function for mp_expt_d_ex() */
-int mp_expt_d(const mp_int *a, mp_digit b, mp_int *c)
+mp_err mp_expt_d(const mp_int *a, mp_digit b, mp_int *c)
 {
    return mp_expt_d_ex(a, b, c, 0);
 }
diff --git a/bn_mp_expt_d_ex.c b/bn_mp_expt_d_ex.c
index 9ce2d13..f10e42b 100644
--- a/bn_mp_expt_d_ex.c
+++ b/bn_mp_expt_d_ex.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* calculate c = a**b  using a square-multiply algorithm */
-int mp_expt_d_ex(const mp_int *a, mp_digit b, mp_int *c, int fast)
+mp_err mp_expt_d_ex(const mp_int *a, mp_digit b, mp_int *c, int fast)
 {
-   int     res;
+   mp_err res;
    unsigned int x;
 
    mp_int  g;
diff --git a/bn_mp_exptmod.c b/bn_mp_exptmod.c
index bcef306..9bf3d8c 100644
--- a/bn_mp_exptmod.c
+++ b/bn_mp_exptmod.c
@@ -8,7 +8,7 @@
  * embedded in the normal function but that wasted alot of stack space
  * for nothing (since 99% of the time the Montgomery code would be called)
  */
-int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
+mp_err mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
 {
    int dr;
 
@@ -21,7 +21,7 @@ int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
    if (X->sign == MP_NEG) {
 #ifdef BN_MP_INVMOD_C
       mp_int tmpG, tmpX;
-      int err;
+      mp_err err;
 
       /* first compute 1/G mod P */
       if ((err = mp_init(&tmpG)) != MP_OKAY) {
@@ -61,7 +61,7 @@ int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
 
 #ifdef BN_MP_DR_IS_MODULUS_C
    /* is it a DR modulus? */
-   dr = mp_dr_is_modulus(P);
+   dr = mp_dr_is_modulus(P) == MP_YES;
 #else
    /* default to no */
    dr = 0;
@@ -70,7 +70,7 @@ int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
 #ifdef BN_MP_REDUCE_IS_2K_C
    /* if not, is it a unrestricted DR modulus? */
    if (dr == 0) {
-      dr = mp_reduce_is_2k(P) << 1;
+      dr = (mp_reduce_is_2k(P) == MP_YES) << 1;
    }
 #endif
 
diff --git a/bn_mp_exteuclid.c b/bn_mp_exteuclid.c
index baeeede..3af7467 100644
--- a/bn_mp_exteuclid.c
+++ b/bn_mp_exteuclid.c
@@ -6,10 +6,10 @@
 /* Extended euclidean algorithm of (a, b) produces
    a*u1 + b*u2 = u3
  */
-int mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
+mp_err mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
 {
    mp_int u1, u2, u3, v1, v2, v3, t1, t2, t3, q, tmp;
-   int err;
+   mp_err err;
 
    if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) {
       return err;
diff --git a/bn_mp_fread.c b/bn_mp_fread.c
index d5c5767..bbb59a5 100644
--- a/bn_mp_fread.c
+++ b/bn_mp_fread.c
@@ -5,9 +5,11 @@
 
 #ifndef MP_NO_FILE
 /* read a bigint from a file stream in ASCII */
-int mp_fread(mp_int *a, int radix, FILE *stream)
+mp_err mp_fread(mp_int *a, int radix, FILE *stream)
 {
-   int err, ch, neg, y;
+   mp_err err;
+   mp_sign neg;
+   int ch, y;
    unsigned pos;
 
    /* clear a */
diff --git a/bn_mp_fwrite.c b/bn_mp_fwrite.c
index 89ab29f..744e5ff 100644
--- a/bn_mp_fwrite.c
+++ b/bn_mp_fwrite.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 #ifndef MP_NO_FILE
-int mp_fwrite(const mp_int *a, int radix, FILE *stream)
+mp_err mp_fwrite(const mp_int *a, int radix, FILE *stream)
 {
    char *buf;
-   int err, len;
+   mp_err err;
+   int len;
 
    if ((err = mp_radix_size(a, radix, &len)) != MP_OKAY) {
       return err;
diff --git a/bn_mp_gcd.c b/bn_mp_gcd.c
index 51cb195..e74372b 100644
--- a/bn_mp_gcd.c
+++ b/bn_mp_gcd.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* Greatest Common Divisor using the binary method */
-int mp_gcd(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_gcd(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  u, v;
-   int     k, u_lsb, v_lsb, res;
+   int     k, u_lsb, v_lsb;
+   mp_err res;
 
    /* either zero than gcd is the largest */
    if (MP_IS_ZERO(a)) {
diff --git a/bn_mp_grow.c b/bn_mp_grow.c
index 7df66f9..9e904c5 100644
--- a/bn_mp_grow.c
+++ b/bn_mp_grow.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* grow as required */
-int mp_grow(mp_int *a, int size)
+mp_err mp_grow(mp_int *a, int size)
 {
    int     i;
    mp_digit *tmp;
diff --git a/bn_mp_ilogb.c b/bn_mp_ilogb.c
index c0f40f7..d72c952 100644
--- a/bn_mp_ilogb.c
+++ b/bn_mp_ilogb.c
@@ -70,9 +70,10 @@ static mp_digit s_digit_ilogb(mp_digit base, mp_digit n)
          as is the output of mp_bitcount.
          With the same problem: max size is INT_MAX * MP_DIGIT not INT_MAX only!
 */
-int mp_ilogb(const mp_int *a, mp_digit base, mp_int *c)
+mp_err mp_ilogb(const mp_int *a, mp_digit base, mp_int *c)
 {
-   int err, cmp;
+   mp_err err;
+   int cmp;
    unsigned int high, low, mid;
    mp_int bracket_low, bracket_high, bracket_mid, t, bi_base;
    mp_digit tmp;
diff --git a/bn_mp_import.c b/bn_mp_import.c
index 93556ea..37685be 100644
--- a/bn_mp_import.c
+++ b/bn_mp_import.c
@@ -6,10 +6,10 @@
 /* based on gmp's mpz_import.
  * see http://gmplib.org/manual/Integer-Import-and-Export.html
  */
-int mp_import(mp_int *rop, size_t count, int order, size_t size,
-              int endian, size_t nails, const void *op)
+mp_err mp_import(mp_int *rop, size_t count, int order, size_t size,
+                 int endian, size_t nails, const void *op)
 {
-   int result;
+   mp_err result;
    size_t odd_nails, nail_bytes, i, j;
    unsigned char odd_nail_mask;
 
diff --git a/bn_mp_incr.c b/bn_mp_incr.c
index 15a9ef5..5e47d2c 100644
--- a/bn_mp_incr.c
+++ b/bn_mp_incr.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* Increment "a" by one like "a++". Changes input! */
-int mp_incr(mp_int *a)
+mp_err mp_incr(mp_int *a)
 {
-   int e = MP_OKAY;
+   mp_err e = MP_OKAY;
    if (MP_IS_ZERO(a)) {
       mp_set(a,1uL);
       return MP_OKAY;
diff --git a/bn_mp_init.c b/bn_mp_init.c
index 99c74aa..2eb7924 100644
--- a/bn_mp_init.c
+++ b/bn_mp_init.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* init a new mp_int */
-int mp_init(mp_int *a)
+mp_err mp_init(mp_int *a)
 {
    /* allocate memory required and clear it */
    a->dp = (mp_digit *) MP_CALLOC((size_t)MP_PREC, sizeof(mp_digit));
diff --git a/bn_mp_init_copy.c b/bn_mp_init_copy.c
index 12f6ffc..e30d501 100644
--- a/bn_mp_init_copy.c
+++ b/bn_mp_init_copy.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* creates "a" then copies b into it */
-int mp_init_copy(mp_int *a, const mp_int *b)
+mp_err mp_init_copy(mp_int *a, const mp_int *b)
 {
-   int     res;
+   mp_err     res;
 
    if ((res = mp_init_size(a, b->used)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_init_multi.c b/bn_mp_init_multi.c
index cd097ee..09fc25f 100644
--- a/bn_mp_init_multi.c
+++ b/bn_mp_init_multi.c
@@ -5,7 +5,7 @@
 
 #include <stdarg.h>
 
-int mp_init_multi(mp_int *mp, ...)
+mp_err mp_init_multi(mp_int *mp, ...)
 {
    mp_err res = MP_OKAY;      /* Assume ok until proven otherwise */
    int n = 0;                 /* Number of ok inits */
diff --git a/bn_mp_init_set.c b/bn_mp_init_set.c
index a041684..5068f2b 100644
--- a/bn_mp_init_set.c
+++ b/bn_mp_init_set.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* initialize and set a digit */
-int mp_init_set(mp_int *a, mp_digit b)
+mp_err mp_init_set(mp_int *a, mp_digit b)
 {
-   int err;
+   mp_err err;
    if ((err = mp_init(a)) != MP_OKAY) {
       return err;
    }
diff --git a/bn_mp_init_set_int.c b/bn_mp_init_set_int.c
index c364c87..fbb2b6b 100644
--- a/bn_mp_init_set_int.c
+++ b/bn_mp_init_set_int.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* initialize and set a digit */
-int mp_init_set_int(mp_int *a, unsigned long b)
+mp_err mp_init_set_int(mp_int *a, unsigned long b)
 {
-   int err;
+   mp_err err;
    if ((err = mp_init(a)) != MP_OKAY) {
       return err;
    }
diff --git a/bn_mp_init_size.c b/bn_mp_init_size.c
index d97f8be..d622687 100644
--- a/bn_mp_init_size.c
+++ b/bn_mp_init_size.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* init an mp_init for a given size */
-int mp_init_size(mp_int *a, int size)
+mp_err mp_init_size(mp_int *a, int size)
 {
    size = MP_MAX(MP_MIN_PREC, size);
 
diff --git a/bn_mp_is_square.c b/bn_mp_is_square.c
index 637f155..3142ac9 100644
--- a/bn_mp_is_square.c
+++ b/bn_mp_is_square.c
@@ -26,9 +26,9 @@ static const char rem_105[105] = {
 };
 
 /* Store non-zero to ret if arg is square, and zero if not */
-int mp_is_square(const mp_int *arg, int *ret)
+mp_err mp_is_square(const mp_int *arg, mp_bool *ret)
 {
-   int           res;
+   mp_err        res;
    mp_digit      c;
    mp_int        t;
    unsigned long r;
diff --git a/bn_mp_iseven.c b/bn_mp_iseven.c
index baea2ad..5cb9622 100644
--- a/bn_mp_iseven.c
+++ b/bn_mp_iseven.c
@@ -3,7 +3,7 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-int mp_iseven(const mp_int *a)
+mp_bool mp_iseven(const mp_int *a)
 {
    return MP_IS_EVEN(a) ? MP_YES : MP_NO;
 }
diff --git a/bn_mp_isodd.c b/bn_mp_isodd.c
index 1f11e2f..bf17646 100644
--- a/bn_mp_isodd.c
+++ b/bn_mp_isodd.c
@@ -3,7 +3,7 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-int mp_isodd(const mp_int *a)
+mp_bool mp_isodd(const mp_int *a)
 {
    return MP_IS_ODD(a) ? MP_YES : MP_NO;
 }
diff --git a/bn_mp_jacobi.c b/bn_mp_jacobi.c
index 04935ca..f050bdf 100644
--- a/bn_mp_jacobi.c
+++ b/bn_mp_jacobi.c
@@ -6,7 +6,7 @@
 /* computes the jacobi c = (a | n) (or Legendre if n is prime)
  * Kept for legacy reasons, please use mp_kronecker() instead
  */
-int mp_jacobi(const mp_int *a, const mp_int *n, int *c)
+mp_err mp_jacobi(const mp_int *a, const mp_int *n, int *c)
 {
    /* if a < 0 return MP_VAL */
    if (a->sign == MP_NEG) {
diff --git a/bn_mp_kronecker.c b/bn_mp_kronecker.c
index a40e7c1..2b7fd6e 100644
--- a/bn_mp_kronecker.c
+++ b/bn_mp_kronecker.c
@@ -17,11 +17,10 @@
      publisher={Springer Science \& Business Media}
     }
  */
-int mp_kronecker(const mp_int *a, const mp_int *p, int *c)
+mp_err mp_kronecker(const mp_int *a, const mp_int *p, int *c)
 {
    mp_int a1, p1, r;
-
-   int e = MP_OKAY;
+   mp_err e = MP_OKAY;
    int v, k;
 
    static const int table[8] = {0, 1, 0, -1, 0, -1, 0, 1};
diff --git a/bn_mp_lcm.c b/bn_mp_lcm.c
index cf95afe..ef7ed12 100644
--- a/bn_mp_lcm.c
+++ b/bn_mp_lcm.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* computes least common multiple as |a*b|/(a, b) */
-int mp_lcm(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_lcm(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res;
+   mp_err  res;
    mp_int  t1, t2;
 
 
diff --git a/bn_mp_lshd.c b/bn_mp_lshd.c
index 7faec30..b8da2b6 100644
--- a/bn_mp_lshd.c
+++ b/bn_mp_lshd.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* shift left a certain amount of digits */
-int mp_lshd(mp_int *a, int b)
+mp_err mp_lshd(mp_int *a, int b)
 {
-   int     x, res;
+   int x;
+   mp_err res;
 
    /* if its less than zero return */
    if (b <= 0) {
diff --git a/bn_mp_mod.c b/bn_mp_mod.c
index 0ef738e..3b0d38f 100644
--- a/bn_mp_mod.c
+++ b/bn_mp_mod.c
@@ -4,10 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */
-int mp_mod(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_mod(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  t;
-   int     res;
+   mp_err  res;
 
    if ((res = mp_init_size(&t, b->used)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_mod_2d.c b/bn_mp_mod_2d.c
index db58771..a02672f 100644
--- a/bn_mp_mod_2d.c
+++ b/bn_mp_mod_2d.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* calc a value mod 2**b */
-int mp_mod_2d(const mp_int *a, int b, mp_int *c)
+mp_err mp_mod_2d(const mp_int *a, int b, mp_int *c)
 {
-   int     x, res;
+   int x;
+   mp_err res;
 
    /* if b is <= 0 then zero the int */
    if (b <= 0) {
diff --git a/bn_mp_mod_d.c b/bn_mp_mod_d.c
index 89f05dc..0b6c12a 100644
--- a/bn_mp_mod_d.c
+++ b/bn_mp_mod_d.c
@@ -3,7 +3,7 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-int mp_mod_d(const mp_int *a, mp_digit b, mp_digit *c)
+mp_err mp_mod_d(const mp_int *a, mp_digit b, mp_digit *c)
 {
    return mp_div_d(a, b, NULL, c);
 }
diff --git a/bn_mp_montgomery_calc_normalization.c b/bn_mp_montgomery_calc_normalization.c
index 1331db1..3648ab3 100644
--- a/bn_mp_montgomery_calc_normalization.c
+++ b/bn_mp_montgomery_calc_normalization.c
@@ -9,9 +9,10 @@
  * The method is slightly modified to shift B unconditionally upto just under
  * the leading bit of b.  This saves alot of multiple precision shifting.
  */
-int mp_montgomery_calc_normalization(mp_int *a, const mp_int *b)
+mp_err mp_montgomery_calc_normalization(mp_int *a, const mp_int *b)
 {
-   int     x, bits, res;
+   int    x, bits;
+   mp_err res;
 
    /* how many bits of last digit does b use */
    bits = mp_count_bits(b) % MP_DIGIT_BIT;
diff --git a/bn_mp_montgomery_reduce.c b/bn_mp_montgomery_reduce.c
index c379675..2640873 100644
--- a/bn_mp_montgomery_reduce.c
+++ b/bn_mp_montgomery_reduce.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* computes xR**-1 == x (mod N) via Montgomery Reduction */
-int mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho)
+mp_err mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho)
 {
-   int     ix, res, digs;
+   int      ix, digs;
+   mp_err   res;
    mp_digit mu;
 
    /* can the fast reduction [comba] method be used?
diff --git a/bn_mp_montgomery_setup.c b/bn_mp_montgomery_setup.c
index ac5f532..39f6e9d 100644
--- a/bn_mp_montgomery_setup.c
+++ b/bn_mp_montgomery_setup.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* setups the montgomery reduction stuff */
-int mp_montgomery_setup(const mp_int *n, mp_digit *rho)
+mp_err mp_montgomery_setup(const mp_int *n, mp_digit *rho)
 {
    mp_digit x, b;
 
diff --git a/bn_mp_mul.c b/bn_mp_mul.c
index 68d8fb8..2fd9df0 100644
--- a/bn_mp_mul.c
+++ b/bn_mp_mul.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* high level multiplication (handles sign) */
-int mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res, neg;
+   mp_err  res;
+   mp_sign neg;
 #ifdef BN_S_MP_BALANCE_MUL_C
    int len_b, len_a;
 #endif
diff --git a/bn_mp_mul_2.c b/bn_mp_mul_2.c
index 75692d3..eba23bf 100644
--- a/bn_mp_mul_2.c
+++ b/bn_mp_mul_2.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* b = a*2 */
-int mp_mul_2(const mp_int *a, mp_int *b)
+mp_err mp_mul_2(const mp_int *a, mp_int *b)
 {
-   int     x, res, oldused;
+   int     x, oldused;
+   mp_err res;
 
    /* grow to accomodate result */
    if (b->alloc < (a->used + 1)) {
diff --git a/bn_mp_mul_2d.c b/bn_mp_mul_2d.c
index f41618b..9ff0d63 100644
--- a/bn_mp_mul_2d.c
+++ b/bn_mp_mul_2d.c
@@ -4,10 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* shift left by a certain bit count */
-int mp_mul_2d(const mp_int *a, int b, mp_int *c)
+mp_err mp_mul_2d(const mp_int *a, int b, mp_int *c)
 {
    mp_digit d;
-   int      res;
+   mp_err   res;
 
    /* copy */
    if (a != c) {
diff --git a/bn_mp_mul_d.c b/bn_mp_mul_d.c
index 74d69ce..fe7ec7b 100644
--- a/bn_mp_mul_d.c
+++ b/bn_mp_mul_d.c
@@ -4,11 +4,12 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* multiply by a digit */
-int mp_mul_d(const mp_int *a, mp_digit b, mp_int *c)
+mp_err mp_mul_d(const mp_int *a, mp_digit b, mp_int *c)
 {
    mp_digit u, *tmpa, *tmpc;
    mp_word  r;
-   int      ix, res, olduse;
+   mp_err   res;
+   int      ix, olduse;
 
    /* make sure c is big enough to hold a*b */
    if (c->alloc < (a->used + 1)) {
diff --git a/bn_mp_mulmod.c b/bn_mp_mulmod.c
index 3c5a63a..10a38db 100644
--- a/bn_mp_mulmod.c
+++ b/bn_mp_mulmod.c
@@ -4,10 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* d = a * b (mod c) */
-int mp_mulmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
+mp_err mp_mulmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
 {
-   int     res;
-   mp_int  t;
+   mp_err res;
+   mp_int t;
 
    if ((res = mp_init_size(&t, c->used)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_n_root.c b/bn_mp_n_root.c
index 3dfbf38..5b5e743 100644
--- a/bn_mp_n_root.c
+++ b/bn_mp_n_root.c
@@ -6,7 +6,7 @@
 /* wrapper function for mp_n_root_ex()
  * computes c = (a)**(1/b) such that (c)**b <= a and (c+1)**b > a
  */
-int mp_n_root(const mp_int *a, mp_digit b, mp_int *c)
+mp_err mp_n_root(const mp_int *a, mp_digit b, mp_int *c)
 {
    return mp_n_root_ex(a, b, c, 0);
 }
diff --git a/bn_mp_n_root_ex.c b/bn_mp_n_root_ex.c
index 42be929..c37f575 100644
--- a/bn_mp_n_root_ex.c
+++ b/bn_mp_n_root_ex.c
@@ -12,11 +12,12 @@
  * which will find the root in log(N) time where
  * each step involves a fair bit.
  */
-int mp_n_root_ex(const mp_int *a, mp_digit b, mp_int *c, int fast)
+mp_err mp_n_root_ex(const mp_int *a, mp_digit b, mp_int *c, int fast)
 {
-   mp_int  t1, t2, t3, a_;
-   int   res, cmp;
-   int ilog2;
+   mp_int t1, t2, t3, a_;
+   int    cmp;
+   int    ilog2;
+   mp_err res;
 
    /* input must be positive if b is even */
    if (((b & 1u) == 0u) && (a->sign == MP_NEG)) {
diff --git a/bn_mp_neg.c b/bn_mp_neg.c
index 1c5b9a0..3ca20f8 100644
--- a/bn_mp_neg.c
+++ b/bn_mp_neg.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* b = -a */
-int mp_neg(const mp_int *a, mp_int *b)
+mp_err mp_neg(const mp_int *a, mp_int *b)
 {
-   int     res;
+   mp_err res;
    if (a != b) {
       if ((res = mp_copy(a, b)) != MP_OKAY) {
          return res;
diff --git a/bn_mp_or.c b/bn_mp_or.c
index f3704f7..5ef3f5a 100644
--- a/bn_mp_or.c
+++ b/bn_mp_or.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* OR two ints together */
-int mp_or(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_or(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res, ix, px;
+   int     ix, px;
+   mp_err  res;
    mp_int  t;
    const mp_int *x;
 
diff --git a/bn_mp_prime_fermat.c b/bn_mp_prime_fermat.c
index c4f7f3b..af3e884 100644
--- a/bn_mp_prime_fermat.c
+++ b/bn_mp_prime_fermat.c
@@ -11,10 +11,10 @@
  *
  * Sets result to 1 if the congruence holds, or zero otherwise.
  */
-int mp_prime_fermat(const mp_int *a, const mp_int *b, int *result)
+mp_err mp_prime_fermat(const mp_int *a, const mp_int *b, mp_bool *result)
 {
    mp_int  t;
-   int     err;
+   mp_err  err;
 
    /* default to composite  */
    *result = MP_NO;
diff --git a/bn_mp_prime_frobenius_underwood.c b/bn_mp_prime_frobenius_underwood.c
index 8855cfb..5b7b099 100644
--- a/bn_mp_prime_frobenius_underwood.c
+++ b/bn_mp_prime_frobenius_underwood.c
@@ -23,12 +23,12 @@
 #else
 #define LTM_FROBENIUS_UNDERWOOD_A 32764
 #endif
-int mp_prime_frobenius_underwood(const mp_int *N, int *result)
+mp_err mp_prime_frobenius_underwood(const mp_int *N, mp_bool *result)
 {
    mp_int T1z, T2z, Np1z, sz, tz;
 
    int a, ap2, length, i, j, isset;
-   int e;
+   mp_err e;
 
    *result = MP_NO;
 
@@ -130,7 +130,7 @@ int mp_prime_frobenius_underwood(const mp_int *N, int *result)
          goto LBL_FU_ERR;
       }
       if ((isset = mp_get_bit(&Np1z, i)) == MP_VAL) {
-         e = isset;
+         e = MP_VAL;
          goto LBL_FU_ERR;
       }
       if (isset == MP_YES) {
diff --git a/bn_mp_prime_is_divisible.c b/bn_mp_prime_is_divisible.c
index 2697cc7..45c1c96 100644
--- a/bn_mp_prime_is_divisible.c
+++ b/bn_mp_prime_is_divisible.c
@@ -8,9 +8,10 @@
  *
  * sets result to 0 if not, 1 if yes
  */
-int mp_prime_is_divisible(const mp_int *a, int *result)
+mp_err mp_prime_is_divisible(const mp_int *a, mp_bool *result)
 {
-   int     err, ix;
+   int      ix;
+   mp_err   err;
    mp_digit res;
 
    /* default to not */
diff --git a/bn_mp_prime_is_prime.c b/bn_mp_prime_is_prime.c
index 7c93020..db94dec 100644
--- a/bn_mp_prime_is_prime.c
+++ b/bn_mp_prime_is_prime.c
@@ -14,10 +14,12 @@ static unsigned int s_floor_ilog2(int value)
 }
 
 
-int mp_prime_is_prime(const mp_int *a, int t, int *result)
+mp_err mp_prime_is_prime(const mp_int *a, int t, mp_bool *result)
 {
    mp_int  b;
-   int     ix, err, res, p_max = 0, size_a, len;
+   int     ix, p_max = 0, size_a, len;
+   mp_bool res;
+   mp_err  err;
    unsigned int fips_rand, mask;
 
    /* default to no */
@@ -32,11 +34,11 @@ int mp_prime_is_prime(const mp_int *a, int t, int *result)
    /* N > 3 */
    if (a->used == 1) {
       if ((a->dp[0] == 0u) || (a->dp[0] == 1u)) {
-         *result = 0;
+         *result = MP_NO;
          return MP_OKAY;
       }
       if (a->dp[0] == 2u) {
-         *result = 1;
+         *result = MP_YES;
          return MP_OKAY;
       }
    }
diff --git a/bn_mp_prime_miller_rabin.c b/bn_mp_prime_miller_rabin.c
index c46dcfb..96470db 100644
--- a/bn_mp_prime_miller_rabin.c
+++ b/bn_mp_prime_miller_rabin.c
@@ -10,10 +10,11 @@
  * Randomly the chance of error is no more than 1/4 and often
  * very much lower.
  */
-int mp_prime_miller_rabin(const mp_int *a, const mp_int *b, int *result)
+mp_err mp_prime_miller_rabin(const mp_int *a, const mp_int *b, mp_bool *result)
 {
    mp_int  n1, y, r;
-   int     s, j, err;
+   mp_err  err;
+   int     s, j;
 
    /* default */
    *result = MP_NO;
diff --git a/bn_mp_prime_next_prime.c b/bn_mp_prime_next_prime.c
index 2e27eed..f5ce9eb 100644
--- a/bn_mp_prime_next_prime.c
+++ b/bn_mp_prime_next_prime.c
@@ -8,9 +8,11 @@
  *
  * bbs_style = 1 means the prime must be congruent to 3 mod 4
  */
-int mp_prime_next_prime(mp_int *a, int t, int bbs_style)
+mp_err mp_prime_next_prime(mp_int *a, int t, int bbs_style)
 {
-   int      err, res = MP_NO, x, y;
+   int      x, y;
+   mp_err  err;
+   mp_bool res = MP_NO;
    mp_digit res_tab[MP_PRIME_SIZE], step, kstep;
    mp_int   b;
 
diff --git a/bn_mp_prime_rand.c b/bn_mp_prime_rand.c
index cd520ff..b4b08ba 100644
--- a/bn_mp_prime_rand.c
+++ b/bn_mp_prime_rand.c
@@ -18,10 +18,12 @@
  */
 
 /* This is possibly the mother of all prime generation functions, muahahahahaha! */
-static int s_mp_prime_random_ex(mp_int *a, int t, int size, int flags, private_mp_prime_callback cb, void *dat)
+static mp_err s_mp_prime_random_ex(mp_int *a, int t, int size, int flags, private_mp_prime_callback cb, void *dat)
 {
    unsigned char *tmp, maskAND, maskOR_msb, maskOR_lsb;
-   int res, err, bsize, maskOR_msb_offset;
+   int bsize, maskOR_msb_offset;
+   mp_bool res;
+   mp_err err;
 
    /* sanity check the input */
    if ((size <= 1) || (t <= 0)) {
@@ -130,12 +132,12 @@ static int s_mp_rand_cb(unsigned char *dst, int len, void *dat)
    return len;
 }
 
-int mp_prime_random_ex(mp_int *a, int t, int size, int flags, private_mp_prime_callback cb, void *dat)
+mp_err mp_prime_random_ex(mp_int *a, int t, int size, int flags, private_mp_prime_callback cb, void *dat)
 {
    return s_mp_prime_random_ex(a, t, size, flags, cb, dat);
 }
 
-int mp_prime_rand(mp_int *a, int t, int size, int flags)
+mp_err mp_prime_rand(mp_int *a, int t, int size, int flags)
 {
    return s_mp_prime_random_ex(a, t, size, flags, s_mp_rand_cb, NULL);
 }
diff --git a/bn_mp_prime_strong_lucas_selfridge.c b/bn_mp_prime_strong_lucas_selfridge.c
index 44143b0..0316cac 100644
--- a/bn_mp_prime_strong_lucas_selfridge.c
+++ b/bn_mp_prime_strong_lucas_selfridge.c
@@ -19,10 +19,11 @@
  * multiply bigint a with int d and put the result in c
  * Like mp_mul_d() but with a signed long as the small input
  */
-static int s_mp_mul_si(const mp_int *a, long d, mp_int *c)
+static mp_err s_mp_mul_si(const mp_int *a, long d, mp_int *c)
 {
    mp_int t;
-   int err, neg = 0;
+   mp_err err;
+   int neg = 0;
 
    if ((err = mp_init(&t)) != MP_OKAY) {
       return err;
@@ -64,13 +65,13 @@ LBL_MPMULSI_ERR:
     (If that name sounds familiar, he is the guy who found the fdiv bug in the
      Pentium (P5x, I think) Intel processor)
 */
-int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
+mp_err mp_prime_strong_lucas_selfridge(const mp_int *a, mp_bool *result)
 {
    /* CZ TODO: choose better variable names! */
    mp_int Dz, gcd, Np1, Uz, Vz, U2mz, V2mz, Qmz, Q2mz, Qkdz, T1z, T2z, T3z, T4z, Q2kdz;
    /* CZ TODO: Some of them need the full 32 bit, hence the (temporary) exclusion of MP_8BIT */
    int32_t D, Ds, J, sign, P, Q, r, s, u, Nbits;
-   int e;
+   mp_err e;
    int isset, oddness;
 
    *result = MP_NO;
@@ -246,7 +247,7 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
          goto LBL_LS_ERR;
       }
       if ((isset = mp_get_bit(&Dz, u)) == MP_VAL) {
-         e = isset;
+         e = MP_VAL;
          goto LBL_LS_ERR;
       }
       if (isset == MP_YES) {
diff --git a/bn_mp_radix_size.c b/bn_mp_radix_size.c
index 8895ae2..ffcc3aa 100644
--- a/bn_mp_radix_size.c
+++ b/bn_mp_radix_size.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* returns size of ASCII reprensentation */
-int mp_radix_size(const mp_int *a, int radix, int *size)
+mp_err mp_radix_size(const mp_int *a, int radix, int *size)
 {
-   int     res, digs;
-   mp_int  t;
+   mp_err  res;
+   int     digs;
+   mp_int   t;
    mp_digit d;
 
    *size = 0;
diff --git a/bn_mp_rand.c b/bn_mp_rand.c
index f347c97..aad48d9 100644
--- a/bn_mp_rand.c
+++ b/bn_mp_rand.c
@@ -3,24 +3,25 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-int (*s_mp_rand_source)(void *out, size_t size) = s_mp_rand_platform;
+mp_err(*s_mp_rand_source)(void *out, size_t size) = s_mp_rand_platform;
 
-void mp_rand_source(int (*source)(void *out, size_t size))
+void mp_rand_source(mp_err(*source)(void *out, size_t size))
 {
    s_mp_rand_source = (source == NULL) ? s_mp_rand_platform : source;
 }
 
 /* makes a pseudo-random int of a given size */
-int mp_rand_digit(mp_digit *r)
+mp_err mp_rand_digit(mp_digit *r)
 {
-   int ret = s_mp_rand_source(r, sizeof(mp_digit));
+   mp_err ret = s_mp_rand_source(r, sizeof(mp_digit));
    *r &= MP_MASK;
    return ret;
 }
 
-int mp_rand(mp_int *a, int digits)
+mp_err mp_rand(mp_int *a, int digits)
 {
-   int ret, i;
+   int i;
+   mp_err ret;
 
    mp_zero(a);
 
diff --git a/bn_mp_read_radix.c b/bn_mp_read_radix.c
index 913c217..57a00cc 100644
--- a/bn_mp_read_radix.c
+++ b/bn_mp_read_radix.c
@@ -6,11 +6,13 @@
 #define MP_TOUPPER(c) ((((c) >= 'a') && ((c) <= 'z')) ? (((c) + 'A') - 'a') : (c))
 
 /* read a string [ASCII] in a given radix */
-int mp_read_radix(mp_int *a, const char *str, int radix)
+mp_err mp_read_radix(mp_int *a, const char *str, int radix)
 {
-   int     y, res, neg;
+   mp_err   res;
+   int      y;
+   mp_sign  neg;
    unsigned pos;
-   char    ch;
+   char     ch;
 
    /* zero the digit bignum */
    mp_zero(a);
diff --git a/bn_mp_read_signed_bin.c b/bn_mp_read_signed_bin.c
index 62fdc0e..6d868cf 100644
--- a/bn_mp_read_signed_bin.c
+++ b/bn_mp_read_signed_bin.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* read signed bin, big endian, first byte is 0==positive or 1==negative */
-int mp_read_signed_bin(mp_int *a, const unsigned char *b, int c)
+mp_err mp_read_signed_bin(mp_int *a, const unsigned char *b, int c)
 {
-   int     res;
+   mp_err res;
 
    /* read magnitude */
    if ((res = mp_read_unsigned_bin(a, b + 1, c - 1)) != MP_OKAY) {
diff --git a/bn_mp_read_unsigned_bin.c b/bn_mp_read_unsigned_bin.c
index bdd8f30..ae4e875 100644
--- a/bn_mp_read_unsigned_bin.c
+++ b/bn_mp_read_unsigned_bin.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* reads a unsigned char array, assumes the msb is stored first [big endian] */
-int mp_read_unsigned_bin(mp_int *a, const unsigned char *b, int c)
+mp_err mp_read_unsigned_bin(mp_int *a, const unsigned char *b, int c)
 {
-   int     res;
+   mp_err res;
 
    /* make sure there are at least two digits */
    if (a->alloc < 2) {
diff --git a/bn_mp_reduce.c b/bn_mp_reduce.c
index e6a8bd2..4b7852b 100644
--- a/bn_mp_reduce.c
+++ b/bn_mp_reduce.c
@@ -7,10 +7,11 @@
  * precomputed via mp_reduce_setup.
  * From HAC pp.604 Algorithm 14.42
  */
-int mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu)
+mp_err mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu)
 {
    mp_int  q;
-   int     res, um = m->used;
+   mp_err  res;
+   int     um = m->used;
 
    /* q = x */
    if ((res = mp_init_copy(&q, x)) != MP_OKAY) {
diff --git a/bn_mp_reduce_2k.c b/bn_mp_reduce_2k.c
index d357c28..0bf2ffb 100644
--- a/bn_mp_reduce_2k.c
+++ b/bn_mp_reduce_2k.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* reduces a modulo n where n is of the form 2**p - d */
-int mp_reduce_2k(mp_int *a, const mp_int *n, mp_digit d)
+mp_err mp_reduce_2k(mp_int *a, const mp_int *n, mp_digit d)
 {
    mp_int q;
-   int    p, res;
+   mp_err res;
+   int    p;
 
    if ((res = mp_init(&q)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_reduce_2k_l.c b/bn_mp_reduce_2k_l.c
index c6b743a..b2905ed 100644
--- a/bn_mp_reduce_2k_l.c
+++ b/bn_mp_reduce_2k_l.c
@@ -7,10 +7,11 @@
    This differs from reduce_2k since "d" can be larger
    than a single digit.
 */
-int mp_reduce_2k_l(mp_int *a, const mp_int *n, const mp_int *d)
+mp_err mp_reduce_2k_l(mp_int *a, const mp_int *n, const mp_int *d)
 {
    mp_int q;
-   int    p, res;
+   mp_err res;
+   int    p;
 
    if ((res = mp_init(&q)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_reduce_2k_setup.c b/bn_mp_reduce_2k_setup.c
index f91de82..bae80d9 100644
--- a/bn_mp_reduce_2k_setup.c
+++ b/bn_mp_reduce_2k_setup.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* determines the setup value */
-int mp_reduce_2k_setup(const mp_int *a, mp_digit *d)
+mp_err mp_reduce_2k_setup(const mp_int *a, mp_digit *d)
 {
-   int res, p;
+   mp_err res;
    mp_int tmp;
+   int    p;
 
    if ((res = mp_init(&tmp)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_reduce_2k_setup_l.c b/bn_mp_reduce_2k_setup_l.c
index aef78b6..652942c 100644
--- a/bn_mp_reduce_2k_setup_l.c
+++ b/bn_mp_reduce_2k_setup_l.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* determines the setup value */
-int mp_reduce_2k_setup_l(const mp_int *a, mp_int *d)
+mp_err mp_reduce_2k_setup_l(const mp_int *a, mp_int *d)
 {
-   int    res;
+   mp_err res;
    mp_int tmp;
 
    if ((res = mp_init(&tmp)) != MP_OKAY) {
diff --git a/bn_mp_reduce_is_2k.c b/bn_mp_reduce_is_2k.c
index ba8958f..fe3aeea 100644
--- a/bn_mp_reduce_is_2k.c
+++ b/bn_mp_reduce_is_2k.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* determines if mp_reduce_2k can be used */
-int mp_reduce_is_2k(const mp_int *a)
+mp_bool mp_reduce_is_2k(const mp_int *a)
 {
    int ix, iy, iw;
    mp_digit iz;
diff --git a/bn_mp_reduce_is_2k_l.c b/bn_mp_reduce_is_2k_l.c
index 2303dc3..b2c7292 100644
--- a/bn_mp_reduce_is_2k_l.c
+++ b/bn_mp_reduce_is_2k_l.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* determines if reduce_2k_l can be used */
-int mp_reduce_is_2k_l(const mp_int *a)
+mp_bool mp_reduce_is_2k_l(const mp_int *a)
 {
    int ix, iy;
 
diff --git a/bn_mp_reduce_setup.c b/bn_mp_reduce_setup.c
index 7cd7909..2e4f961 100644
--- a/bn_mp_reduce_setup.c
+++ b/bn_mp_reduce_setup.c
@@ -6,10 +6,9 @@
 /* pre-calculate the value required for Barrett reduction
  * For a given modulus "b" it calulates the value required in "a"
  */
-int mp_reduce_setup(mp_int *a, const mp_int *b)
+mp_err mp_reduce_setup(mp_int *a, const mp_int *b)
 {
-   int     res;
-
+   mp_err res;
    if ((res = mp_2expt(a, b->used * 2 * MP_DIGIT_BIT)) != MP_OKAY) {
       return res;
    }
diff --git a/bn_mp_set_double.c b/bn_mp_set_double.c
index bd2ea37..efb8533 100644
--- a/bn_mp_set_double.c
+++ b/bn_mp_set_double.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 #if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559)
-int mp_set_double(mp_int *a, double b)
+mp_err mp_set_double(mp_int *a, double b)
 {
    uint64_t frac;
-   int exp, res;
+   int exp;
+   mp_err res;
    union {
       double   dbl;
       uint64_t bits;
diff --git a/bn_mp_set_int.c b/bn_mp_set_int.c
index 90573bb..a322580 100644
--- a/bn_mp_set_int.c
+++ b/bn_mp_set_int.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* set a 32-bit const */
-int mp_set_int(mp_int *a, unsigned long b)
+mp_err mp_set_int(mp_int *a, unsigned long b)
 {
    return mp_set_long(a, b & 0xFFFFFFFFUL);
 }
diff --git a/bn_mp_shrink.c b/bn_mp_shrink.c
index 28754f5..8b404e0 100644
--- a/bn_mp_shrink.c
+++ b/bn_mp_shrink.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* shrink a bignum */
-int mp_shrink(mp_int *a)
+mp_err mp_shrink(mp_int *a)
 {
    static int static_check[-(MP_PREC < MP_MIN_PREC)];
    mp_digit *tmp;
diff --git a/bn_mp_sqr.c b/bn_mp_sqr.c
index 5b93eab..e1e243c 100644
--- a/bn_mp_sqr.c
+++ b/bn_mp_sqr.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* computes b = a*a */
-int mp_sqr(const mp_int *a, mp_int *b)
+mp_err mp_sqr(const mp_int *a, mp_int *b)
 {
-   int     res;
+   mp_err res;
 
 #ifdef BN_S_MP_TOOM_SQR_C
    /* use Toom-Cook? */
diff --git a/bn_mp_sqrmod.c b/bn_mp_sqrmod.c
index fd72388..30d7c46 100644
--- a/bn_mp_sqrmod.c
+++ b/bn_mp_sqrmod.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* c = a * a (mod b) */
-int mp_sqrmod(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_sqrmod(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res;
+   mp_err  res;
    mp_int  t;
 
    if ((res = mp_init(&t)) != MP_OKAY) {
diff --git a/bn_mp_sqrt.c b/bn_mp_sqrt.c
index ab9141c..74769f5 100644
--- a/bn_mp_sqrt.c
+++ b/bn_mp_sqrt.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* this function is less generic than mp_n_root, simpler and faster */
-int mp_sqrt(const mp_int *arg, mp_int *ret)
+mp_err mp_sqrt(const mp_int *arg, mp_int *ret)
 {
-   int res;
+   mp_err res;
    mp_int t1, t2;
 
    /* must be positive */
diff --git a/bn_mp_sqrtmod_prime.c b/bn_mp_sqrtmod_prime.c
index 354e9f4..86934cd 100644
--- a/bn_mp_sqrtmod_prime.c
+++ b/bn_mp_sqrtmod_prime.c
@@ -9,9 +9,10 @@
  *
  */
 
-int mp_sqrtmod_prime(const mp_int *n, const mp_int *prime, mp_int *ret)
+mp_err mp_sqrtmod_prime(const mp_int *n, const mp_int *prime, mp_int *ret)
 {
-   int res, legendre;
+   mp_err res;
+   int legendre;
    mp_int t1, C, Q, S, Z, M, T, R, two;
    mp_digit i;
 
diff --git a/bn_mp_sub.c b/bn_mp_sub.c
index 48cc06f..00df09e 100644
--- a/bn_mp_sub.c
+++ b/bn_mp_sub.c
@@ -4,12 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* high level subtraction (handles signs) */
-int mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     sa, sb, res;
-
-   sa = a->sign;
-   sb = b->sign;
+   mp_sign sa = a->sign, sb = b->sign;
+   mp_err res;
 
    if (sa != sb) {
       /* subtract a negative from a positive, OR */
diff --git a/bn_mp_sub_d.c b/bn_mp_sub_d.c
index fc45f97..c953b61 100644
--- a/bn_mp_sub_d.c
+++ b/bn_mp_sub_d.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* single digit subtraction */
-int mp_sub_d(const mp_int *a, mp_digit b, mp_int *c)
+mp_err mp_sub_d(const mp_int *a, mp_digit b, mp_int *c)
 {
    mp_digit *tmpa, *tmpc, mu;
-   int       res, ix, oldused;
+   mp_err    res;
+   int       ix, oldused;
 
    /* grow c as required */
    if (c->alloc < (a->used + 1)) {
diff --git a/bn_mp_submod.c b/bn_mp_submod.c
index a2157af..f265eb1 100644
--- a/bn_mp_submod.c
+++ b/bn_mp_submod.c
@@ -4,11 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* d = a - b (mod c) */
-int mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
+mp_err mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
 {
-   int     res;
-   mp_int  t;
-
+   mp_err res;
+   mp_int t;
 
    if ((res = mp_init(&t)) != MP_OKAY) {
       return res;
diff --git a/bn_mp_tc_and.c b/bn_mp_tc_and.c
index 9a6f528..6361f4c 100644
--- a/bn_mp_tc_and.c
+++ b/bn_mp_tc_and.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* two complement and */
-int mp_tc_and(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_tc_and(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int res = MP_OKAY, bits, abits, bbits;
-   int sa = a->sign, sb = b->sign;
+   mp_err res = MP_OKAY;
+   int bits, abits, bbits;
+   mp_sign sa = a->sign, sb = b->sign;
    mp_int *mx = NULL, _mx, acpy, bcpy;
 
    if ((sa == MP_NEG) || (sb == MP_NEG)) {
diff --git a/bn_mp_tc_div_2d.c b/bn_mp_tc_div_2d.c
index 99945dd..fcb66b6 100644
--- a/bn_mp_tc_div_2d.c
+++ b/bn_mp_tc_div_2d.c
@@ -4,9 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* two complement right shift */
-int mp_tc_div_2d(const mp_int *a, int b, mp_int *c)
+mp_err mp_tc_div_2d(const mp_int *a, int b, mp_int *c)
 {
-   int res;
+   mp_err res;
    if (a->sign == MP_ZPOS) {
       return mp_div_2d(a, b, c, NULL);
    }
diff --git a/bn_mp_tc_or.c b/bn_mp_tc_or.c
index 93cb520..e4cd756 100644
--- a/bn_mp_tc_or.c
+++ b/bn_mp_tc_or.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* two complement or */
-int mp_tc_or(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_tc_or(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int res = MP_OKAY, bits, abits, bbits;
-   int sa = a->sign, sb = b->sign;
+   mp_err res = MP_OKAY;
+   int bits, abits, bbits;
+   mp_sign sa = a->sign, sb = b->sign;
    mp_int *mx = NULL, _mx, acpy, bcpy;
 
    if ((sa == MP_NEG) || (sb == MP_NEG)) {
diff --git a/bn_mp_tc_xor.c b/bn_mp_tc_xor.c
index ff4189c..21d46df 100644
--- a/bn_mp_tc_xor.c
+++ b/bn_mp_tc_xor.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* two complement xor */
-int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int res = MP_OKAY, bits, abits, bbits;
-   int sa = a->sign, sb = b->sign;
+   mp_err res = MP_OKAY;
+   int bits, abits, bbits;
+   mp_sign sa = a->sign, sb = b->sign;
    mp_int *mx = NULL, _mx, acpy, bcpy;
 
    if ((sa == MP_NEG) || (sb == MP_NEG)) {
diff --git a/bn_mp_to_signed_bin.c b/bn_mp_to_signed_bin.c
index c281f3f..6561ea8 100644
--- a/bn_mp_to_signed_bin.c
+++ b/bn_mp_to_signed_bin.c
@@ -4,10 +4,9 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* store in signed [big endian] format */
-int mp_to_signed_bin(const mp_int *a, unsigned char *b)
+mp_err mp_to_signed_bin(const mp_int *a, unsigned char *b)
 {
-   int     res;
-
+   mp_err res;
    if ((res = mp_to_unsigned_bin(a, b + 1)) != MP_OKAY) {
       return res;
    }
diff --git a/bn_mp_to_signed_bin_n.c b/bn_mp_to_signed_bin_n.c
index 9ee6922..4c36cb5 100644
--- a/bn_mp_to_signed_bin_n.c
+++ b/bn_mp_to_signed_bin_n.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* store in signed [big endian] format */
-int mp_to_signed_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen)
+mp_err mp_to_signed_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen)
 {
    if (*outlen < (unsigned long)mp_signed_bin_size(a)) {
       return MP_VAL;
diff --git a/bn_mp_to_unsigned_bin.c b/bn_mp_to_unsigned_bin.c
index 13e7d2e..6a03625 100644
--- a/bn_mp_to_unsigned_bin.c
+++ b/bn_mp_to_unsigned_bin.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* store in unsigned [big endian] format */
-int mp_to_unsigned_bin(const mp_int *a, unsigned char *b)
+mp_err mp_to_unsigned_bin(const mp_int *a, unsigned char *b)
 {
-   int     x, res;
+   int     x;
+   mp_err  res;
    mp_int  t;
 
    if ((res = mp_init_copy(&t, a)) != MP_OKAY) {
diff --git a/bn_mp_to_unsigned_bin_n.c b/bn_mp_to_unsigned_bin_n.c
index bf47c74..3c08465 100644
--- a/bn_mp_to_unsigned_bin_n.c
+++ b/bn_mp_to_unsigned_bin_n.c
@@ -4,7 +4,7 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* store in unsigned [big endian] format */
-int mp_to_unsigned_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen)
+mp_err mp_to_unsigned_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen)
 {
    if (*outlen < (unsigned long)mp_unsigned_bin_size(a)) {
       return MP_VAL;
diff --git a/bn_mp_toradix.c b/bn_mp_toradix.c
index 7a6d544..856ff25 100644
--- a/bn_mp_toradix.c
+++ b/bn_mp_toradix.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* stores a bignum as a ASCII string in a given radix (2..64) */
-int mp_toradix(const mp_int *a, char *str, int radix)
+mp_err mp_toradix(const mp_int *a, char *str, int radix)
 {
-   int     res, digs;
+   mp_err  res;
+   int digs;
    mp_int  t;
    mp_digit d;
    char   *_s = str;
diff --git a/bn_mp_toradix_n.c b/bn_mp_toradix_n.c
index 2f0018a..755952e 100644
--- a/bn_mp_toradix_n.c
+++ b/bn_mp_toradix_n.c
@@ -7,9 +7,10 @@
  *
  * Stores upto maxlen-1 chars and always a NULL byte
  */
-int mp_toradix_n(const mp_int *a, char *str, int radix, int maxlen)
+mp_err mp_toradix_n(const mp_int *a, char *str, int radix, int maxlen)
 {
-   int     res, digs;
+   int     digs;
+   mp_err  res;
    mp_int  t;
    mp_digit d;
    char   *_s = str;
diff --git a/bn_mp_xor.c b/bn_mp_xor.c
index a61c8fe..a8a7778 100644
--- a/bn_mp_xor.c
+++ b/bn_mp_xor.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* XOR two ints together */
-int mp_xor(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err mp_xor(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     res, ix, px;
+   int     ix, px;
+   mp_err  res;
    mp_int  t;
    const mp_int *x;
 
diff --git a/bn_s_mp_add.c b/bn_s_mp_add.c
index e87dc9f..83df1d3 100644
--- a/bn_s_mp_add.c
+++ b/bn_s_mp_add.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* low level addition, based on HAC pp.594, Algorithm 14.7 */
-int s_mp_add(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_add(const mp_int *a, const mp_int *b, mp_int *c)
 {
    const mp_int *x;
-   int     olduse, res, min, max;
+   mp_err res;
+   int     olduse, min, max;
 
    /* find sizes, we let |a| <= |b| which means we have to sort
     * them.  "x" will point to the input with the most digits
diff --git a/bn_s_mp_balance_mul.c b/bn_s_mp_balance_mul.c
index ed17a3e..f8de2ec 100644
--- a/bn_s_mp_balance_mul.c
+++ b/bn_s_mp_balance_mul.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* single-digit multiplication with the smaller number as the single-digit */
-int s_mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int e, count, len_a, len_b, nblocks, i, j, bsize;
+   int count, len_a, len_b, nblocks, i, j, bsize;
    mp_int a0, tmp, A, B, r;
+   mp_err e;
 
    len_a = a->used;
    len_b = b->used;
diff --git a/bn_s_mp_exptmod.c b/bn_s_mp_exptmod.c
index 20572d4..b1cc0e9 100644
--- a/bn_s_mp_exptmod.c
+++ b/bn_s_mp_exptmod.c
@@ -9,12 +9,13 @@
 #   define TAB_SIZE 256
 #endif
 
-int s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
+mp_err s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
 {
    mp_int  M[TAB_SIZE], res, mu;
    mp_digit buf;
-   int     err, bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize;
-   int (*redux)(mp_int *x, const mp_int *m, const mp_int *mu);
+   mp_err   err;
+   int      bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize;
+   mp_err(*redux)(mp_int *x, const mp_int *m, const mp_int *mu);
 
    /* find window size */
    x = mp_count_bits(X);
diff --git a/bn_s_mp_exptmod_fast.c b/bn_s_mp_exptmod_fast.c
index d6373ef..6b4483c 100644
--- a/bn_s_mp_exptmod_fast.c
+++ b/bn_s_mp_exptmod_fast.c
@@ -17,17 +17,18 @@
 #   define TAB_SIZE 256
 #endif
 
-int s_mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
+mp_err s_mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
 {
    mp_int  M[TAB_SIZE], res;
    mp_digit buf, mp;
-   int     err, bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize;
+   int     bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize;
+   mp_err   err;
 
    /* use a pointer to the reduction algorithm.  This allows us to use
     * one of many reduction algorithms without modding the guts of
     * the code with if statements everywhere.
     */
-   int (*redux)(mp_int *x, const mp_int *n, mp_digit rho);
+   mp_err(*redux)(mp_int *x, const mp_int *n, mp_digit rho);
 
    /* find window size */
    x = mp_count_bits(X);
diff --git a/bn_s_mp_invmod_fast.c b/bn_s_mp_invmod_fast.c
index 071b76d..111ecdd 100644
--- a/bn_s_mp_invmod_fast.c
+++ b/bn_s_mp_invmod_fast.c
@@ -9,10 +9,11 @@
  * Based on slow invmod except this is optimized for the case where b is
  * odd as per HAC Note 14.64 on pp. 610
  */
-int s_mp_invmod_fast(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_invmod_fast(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  x, y, u, v, B, D;
-   int     res, neg;
+   mp_sign neg;
+   mp_err  res;
 
    /* 2. [modified] b must be odd   */
    if (MP_IS_EVEN(b)) {
diff --git a/bn_s_mp_invmod_slow.c b/bn_s_mp_invmod_slow.c
index dbafde1..b006aed 100644
--- a/bn_s_mp_invmod_slow.c
+++ b/bn_s_mp_invmod_slow.c
@@ -4,10 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* hac 14.61, pp608 */
-int s_mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  x, y, u, v, A, B, C, D;
-   int     res;
+   mp_err  res;
 
    /* b cannot be negative */
    if ((b->sign == MP_NEG) || MP_IS_ZERO(b)) {
diff --git a/bn_s_mp_karatsuba_mul.c b/bn_s_mp_karatsuba_mul.c
index 15d3b11..6ef96c7 100644
--- a/bn_s_mp_karatsuba_mul.c
+++ b/bn_s_mp_karatsuba_mul.c
@@ -32,13 +32,11 @@
  * Generally though the overhead of this method doesn't pay off
  * until a certain size (N ~ 80) is reached.
  */
-int s_mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int  x0, x1, y0, y1, t1, x0y0, x1y1;
-   int     B, err;
-
-   /* default the return code to an error */
-   err = MP_MEM;
+   int     B;
+   mp_err  err = MP_MEM; /* default the return code to an error */
 
    /* min # of digits */
    B = MP_MIN(a->used, b->used);
diff --git a/bn_s_mp_karatsuba_sqr.c b/bn_s_mp_karatsuba_sqr.c
index 8a3069b..f132d07 100644
--- a/bn_s_mp_karatsuba_sqr.c
+++ b/bn_s_mp_karatsuba_sqr.c
@@ -10,12 +10,11 @@
  * is essentially the same algorithm but merely
  * tuned to perform recursive squarings.
  */
-int s_mp_karatsuba_sqr(const mp_int *a, mp_int *b)
+mp_err s_mp_karatsuba_sqr(const mp_int *a, mp_int *b)
 {
    mp_int  x0, x1, t1, t2, x0x0, x1x1;
-   int     B, err;
-
-   err = MP_MEM;
+   int     B;
+   mp_err  err = MP_MEM;
 
    /* min # of digits */
    B = a->used;
diff --git a/bn_s_mp_montgomery_reduce_fast.c b/bn_s_mp_montgomery_reduce_fast.c
index 688049c..4e69af6 100644
--- a/bn_s_mp_montgomery_reduce_fast.c
+++ b/bn_s_mp_montgomery_reduce_fast.c
@@ -11,9 +11,10 @@
  *
  * Based on Algorithm 14.32 on pp.601 of HAC.
 */
-int s_mp_montgomery_reduce_fast(mp_int *x, const mp_int *n, mp_digit rho)
+mp_err s_mp_montgomery_reduce_fast(mp_int *x, const mp_int *n, mp_digit rho)
 {
-   int     ix, res, olduse;
+   int     ix, olduse;
+   mp_err  res;
    mp_word W[MP_WARRAY];
 
    if (x->used > (int)MP_WARRAY) {
diff --git a/bn_s_mp_mul_digs.c b/bn_s_mp_mul_digs.c
index 87b785c..109505b 100644
--- a/bn_s_mp_mul_digs.c
+++ b/bn_s_mp_mul_digs.c
@@ -7,10 +7,11 @@
  * HAC pp. 595, Algorithm 14.12  Modified so you can control how
  * many digits of output are created.
  */
-int s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
    mp_int  t;
-   int     res, pa, pb, ix, iy;
+   mp_err  res;
+   int     pa, pb, ix, iy;
    mp_digit u;
    mp_word r;
    mp_digit tmpx, *tmpt, *tmpy;
diff --git a/bn_s_mp_mul_digs_fast.c b/bn_s_mp_mul_digs_fast.c
index 2361433..9c3776c 100644
--- a/bn_s_mp_mul_digs_fast.c
+++ b/bn_s_mp_mul_digs_fast.c
@@ -19,9 +19,10 @@
  * Based on Algorithm 14.12 on pp.595 of HAC.
  *
  */
-int s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
-   int     olduse, res, pa, ix, iz;
+   int      olduse, pa, ix, iz;
+   mp_err   res;
    mp_digit W[MP_WARRAY];
    mp_word  _W;
 
diff --git a/bn_s_mp_mul_high_digs.c b/bn_s_mp_mul_high_digs.c
index 14b889e..7a13991 100644
--- a/bn_s_mp_mul_high_digs.c
+++ b/bn_s_mp_mul_high_digs.c
@@ -6,12 +6,13 @@
 /* multiplies |a| * |b| and does not compute the lower digs digits
  * [meant to get the higher part of the product]
  */
-int s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
-   mp_int  t;
-   int     res, pa, pb, ix, iy;
+   mp_int   t;
+   int      pa, pb, ix, iy;
+   mp_err   res;
    mp_digit u;
-   mp_word r;
+   mp_word  r;
    mp_digit tmpx, *tmpt, *tmpy;
 
    /* can we use the fast multiplier? */
diff --git a/bn_s_mp_mul_high_digs_fast.c b/bn_s_mp_mul_high_digs_fast.c
index 27242a1..36cb2d1 100644
--- a/bn_s_mp_mul_high_digs_fast.c
+++ b/bn_s_mp_mul_high_digs_fast.c
@@ -12,9 +12,10 @@
  *
  * Based on Algorithm 14.12 on pp.595 of HAC.
  */
-int s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
+mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
 {
-   int     olduse, res, pa, ix, iz;
+   int     olduse, pa, ix, iz;
+   mp_err   res;
    mp_digit W[MP_WARRAY];
    mp_word  _W;
 
diff --git a/bn_s_mp_rand_jenkins.c b/bn_s_mp_rand_jenkins.c
index a310bea..a914458 100644
--- a/bn_s_mp_rand_jenkins.c
+++ b/bn_s_mp_rand_jenkins.c
@@ -35,7 +35,7 @@ void s_mp_rand_jenkins_init(uint64_t seed)
    }
 }
 
-int s_mp_rand_jenkins(void *p, size_t n)
+mp_err s_mp_rand_jenkins(void *p, size_t n)
 {
    char *q = (char *)p;
    while (n > 0u) {
diff --git a/bn_s_mp_rand_platform.c b/bn_s_mp_rand_platform.c
index ec2f008..a4da912 100644
--- a/bn_s_mp_rand_platform.c
+++ b/bn_s_mp_rand_platform.c
@@ -26,7 +26,7 @@
 #include <windows.h>
 #include <wincrypt.h>
 
-static int s_read_win_csp(void *p, size_t n)
+static mp_err s_read_win_csp(void *p, size_t n)
 {
    static HCRYPTPROV hProv = 0;
    if (hProv == 0) {
@@ -49,7 +49,7 @@ static int s_read_win_csp(void *p, size_t n)
 #include <sys/random.h>
 #include <errno.h>
 
-static int s_read_getrandom(void *p, size_t n)
+static mp_err s_read_getrandom(void *p, size_t n)
 {
    char *q = (char *)p;
    while (n > 0u) {
@@ -79,7 +79,7 @@ static int s_read_getrandom(void *p, size_t n)
 #include <errno.h>
 #include <unistd.h>
 
-static int s_read_dev_urandom(void *p, size_t n)
+static mp_err s_read_dev_urandom(void *p, size_t n)
 {
    int fd;
    char *q = (char *)p;
@@ -111,7 +111,7 @@ static int s_read_dev_urandom(void *p, size_t n)
 unsigned long (*ltm_rng)(unsigned char *out, unsigned long outlen, void (*callback)(void));
 void (*ltm_rng_callback)(void);
 
-static int s_read_ltm_rng(void *p, size_t n)
+static mp_err s_read_ltm_rng(void *p, size_t n)
 {
    unsigned long ret;
    if (ltm_rng == NULL) return MP_ERR;
@@ -121,14 +121,14 @@ static int s_read_ltm_rng(void *p, size_t n)
 }
 #endif
 
-int s_mp_rand_platform(void *p, size_t n)
+mp_err s_mp_rand_platform(void *p, size_t n)
 {
 #if defined(MP_ARC4RANDOM)
    arc4random_buf(p, n);
    return MP_OKAY;
 #else
 
-   int ret = MP_ERR;
+   mp_err ret = MP_ERR;
 
 #if defined(MP_WIN_CSP)
    ret = s_read_win_csp(p, n);
diff --git a/bn_s_mp_sqr.c b/bn_s_mp_sqr.c
index b6f0ea0..650f461 100644
--- a/bn_s_mp_sqr.c
+++ b/bn_s_mp_sqr.c
@@ -4,11 +4,12 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* low level squaring, b = a*a, HAC pp.596-597, Algorithm 14.16 */
-int s_mp_sqr(const mp_int *a, mp_int *b)
+mp_err s_mp_sqr(const mp_int *a, mp_int *b)
 {
-   mp_int  t;
-   int     res, ix, iy, pa;
-   mp_word r;
+   mp_int   t;
+   int      ix, iy, pa;
+   mp_err   res;
+   mp_word  r;
    mp_digit u, tmpx, *tmpt;
 
    pa = a->used;
diff --git a/bn_s_mp_sqr_fast.c b/bn_s_mp_sqr_fast.c
index 304500c..95acd7a 100644
--- a/bn_s_mp_sqr_fast.c
+++ b/bn_s_mp_sqr_fast.c
@@ -13,11 +13,12 @@
 After that loop you do the squares and add them in.
 */
 
-int s_mp_sqr_fast(const mp_int *a, mp_int *b)
+mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
 {
-   int       olduse, res, pa, ix, iz;
-   mp_digit   W[MP_WARRAY], *tmpx;
+   int       olduse, pa, ix, iz;
+   mp_digit  W[MP_WARRAY], *tmpx;
    mp_word   W1;
+   mp_err    res;
 
    /* grow the destination as required */
    pa = a->used + a->used;
diff --git a/bn_s_mp_sub.c b/bn_s_mp_sub.c
index ffd8272..d00e0e4 100644
--- a/bn_s_mp_sub.c
+++ b/bn_s_mp_sub.c
@@ -4,9 +4,10 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* low level subtraction (assumes |a| > |b|), HAC pp.595 Algorithm 14.9 */
-int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   int     olduse, res, min, max;
+   int    olduse, min, max;
+   mp_err res;
 
    /* find sizes */
    min = b->used;
diff --git a/bn_s_mp_toom_mul.c b/bn_s_mp_toom_mul.c
index 2156139..9f10761 100644
--- a/bn_s_mp_toom_mul.c
+++ b/bn_s_mp_toom_mul.c
@@ -10,10 +10,11 @@
  * only particularly useful on VERY large inputs
  * (we're talking 1000s of digits here...).
 */
-int s_mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c)
+mp_err s_mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
    mp_int w0, w1, w2, w3, w4, tmp1, tmp2, a0, a1, a2, b0, b1, b2;
-   int res, B;
+   int B;
+   mp_err res;
 
    /* init temps */
    if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4,
diff --git a/bn_s_mp_toom_sqr.c b/bn_s_mp_toom_sqr.c
index 72cbea8..24fb4d9 100644
--- a/bn_s_mp_toom_sqr.c
+++ b/bn_s_mp_toom_sqr.c
@@ -4,10 +4,11 @@
 /* SPDX-License-Identifier: Unlicense */
 
 /* squaring using Toom-Cook 3-way algorithm */
-int s_mp_toom_sqr(const mp_int *a, mp_int *b)
+mp_err s_mp_toom_sqr(const mp_int *a, mp_int *b)
 {
    mp_int w0, w1, w2, w3, w4, tmp1, a0, a1, a2;
-   int res, B;
+   int B;
+   mp_err res;
 
    /* init temps */
    if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL)) != MP_OKAY) {
diff --git a/demo/main.c b/demo/main.c
index 068e31a..4cebb12 100644
--- a/demo/main.c
+++ b/demo/main.c
@@ -9,7 +9,7 @@ void ndraw(mp_int *a, const char *name)
    int size;
 
    mp_radix_size(a, 10, &size);
-   buf = malloc((size_t) size);
+   buf = (char *)malloc((size_t) size);
    if (buf == NULL) {
       fprintf(stderr, "\nndraw: malloc(%d) failed\n", size);
       exit(EXIT_FAILURE);
diff --git a/demo/test.c b/demo/test.c
index c4314d0..4e5339e 100644
--- a/demo/test.c
+++ b/demo/test.c
@@ -94,7 +94,7 @@ LBL_ERR:
    return EXIT_FAILURE;
 }
 
-static int very_random_source(void *out, size_t size)
+static mp_err very_random_source(void *out, size_t size)
 {
    memset(out, 0xff, size);
    return MP_OKAY;
@@ -103,7 +103,8 @@ static int very_random_source(void *out, size_t size)
 static int test_mp_rand(void)
 {
    mp_int a, b;
-   int err, n;
+   int n;
+   mp_err err;
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
       return EXIT_FAILURE;
    }
@@ -147,8 +148,8 @@ static int test_mp_jacobi(void)
       { 9, { -1,  1,  0,  1,  1,  0,  1,  1,  0,  1,  1,  0,  1,  1,  0,  1 } },
    };
 
-   int i, n, err, should, cnt;
-
+   int i, n, should, cnt;
+   mp_err err;
    mp_int a, b;
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
       return EXIT_FAILURE;
@@ -225,8 +226,8 @@ static int test_mp_kronecker(void)
    };
 
    long k, m;
-   int i, err, cnt;
-
+   int i, cnt;
+   mp_err err;
    mp_int a, b;
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
       return EXIT_FAILURE;
@@ -718,6 +719,8 @@ static int test_mp_is_square(void)
    int i, n;
 
    mp_int a, b;
+   mp_bool res;
+
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
       return EXIT_FAILURE;
    }
@@ -730,22 +733,22 @@ static int test_mp_is_square(void)
       n = (rand_int() & 7) + 1;
       mp_rand(&a, n);
       mp_sqr(&a, &a);
-      if (mp_is_square(&a, &n) != MP_OKAY) {
+      if (mp_is_square(&a, &res) != MP_OKAY) {
          printf("\nfn:mp_is_square() error!");
          goto LBL_ERR;
       }
-      if (n == 0) {
+      if (res == MP_NO) {
          printf("\nfn:mp_is_square() bad result!");
          goto LBL_ERR;
       }
 
       /* test for false positives */
       mp_add_d(&a, 1uL, &a);
-      if (mp_is_square(&a, &n) != MP_OKAY) {
+      if (mp_is_square(&a, &res) != MP_OKAY) {
          printf("\nfp:mp_is_square() error!");
          goto LBL_ERR;
       }
-      if (n == 1) {
+      if (res == MP_YES) {
          printf("\nfp:mp_is_square() bad result!");
          goto LBL_ERR;
       }
@@ -804,8 +807,8 @@ LBL_ERR:
 
 static int test_mp_prime_rand(void)
 {
-   int ix, err;
-
+   int ix;
+   mp_err err;
    mp_int a, b;
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
       return EXIT_FAILURE;
@@ -836,7 +839,9 @@ LBL_ERR:
 
 static int test_mp_prime_is_prime(void)
 {
-   int ix, err, cnt;
+   int ix;
+   mp_err err;
+   mp_bool cnt;
 
    mp_int a, b;
    if (mp_init_multi(&a, &b, NULL)!= MP_OKAY) {
diff --git a/dep.pl b/dep.pl
index fb610c1..6625cb2 100755
--- a/dep.pl
+++ b/dep.pl
@@ -98,6 +98,7 @@ EOS
    foreach my $line (split /\n/, $content) {
       while ($line =~ /(fast_)?(s_)?mp\_[a-z_0-9]*(?=\()/g) {
           my $a = $&;
+          next if $a eq "mp_err";
           $a =~ tr/[a-z]/[A-Z]/;
           $a = 'BN_' . $a . '_C';
           if (!($list =~ /$a/)) {
diff --git a/makefile_include.mk b/makefile_include.mk
index d7d4cba..aad3896 100644
--- a/makefile_include.mk
+++ b/makefile_include.mk
@@ -61,6 +61,9 @@ endif
 
 ifdef CONV_WARNINGS
 CFLAGS += -std=c89 -Wconversion -Wsign-conversion
+ifeq ($(CONV_WARNINGS), strict)
+CFLAGS += -DMP_USE_ENUMS -Wc++-compat
+endif
 else
 CFLAGS += -Wsystem-headers
 endif
diff --git a/tommath.h b/tommath.h
index 9603167..821a13d 100644
--- a/tommath.h
+++ b/tommath.h
@@ -97,24 +97,6 @@ typedef uint64_t             mp_word;
 #define MP_MASK          ((((mp_digit)1)<<((mp_digit)MP_DIGIT_BIT))-((mp_digit)1))
 #define MP_DIGIT_MAX     MP_MASK
 
-/* equalities */
-#define MP_LT        -1   /* less than */
-#define MP_EQ         0   /* equal to */
-#define MP_GT         1   /* greater than */
-
-#define MP_ZPOS       0   /* positive integer */
-#define MP_NEG        1   /* negative */
-
-#define MP_OKAY       0   /* ok result */
-#define MP_ERR        -1  /* unknown error */
-#define MP_MEM        -2  /* out of mem */
-#define MP_VAL        -3  /* invalid input */
-#define MP_RANGE      MP_VAL
-#define MP_ITER       -4  /* Max. iterations reached */
-
-#define MP_YES        1   /* yes response */
-#define MP_NO         0   /* no response */
-
 /* Primality generation flags */
 #define MP_PRIME_BBS      0x0001 /* BBS style prime */
 #define MP_PRIME_SAFE     0x0002 /* Safe prime (p-1)/2 == prime */
@@ -124,7 +106,47 @@ typedef uint64_t             mp_word;
 #define LTM_PRIME_SAFE     (MP_DEPRECATED_PRAGMA("LTM_PRIME_SAFE has been deprecated, use MP_PRIME_SAFE") MP_PRIME_SAFE)
 #define LTM_PRIME_2MSB_ON  (MP_DEPRECATED_PRAGMA("LTM_PRIME_2MSB_ON has been deprecated, use MP_PRIME_2MSB_ON") MP_PRIME_2MSB_ON)
 
-typedef int           mp_err;
+#ifdef MP_USE_ENUMS
+typedef enum {
+   MP_ZPOS = 0,
+   MP_NEG = 1
+} mp_sign;
+typedef enum {
+   MP_LT = -1,
+   MP_EQ = 0,
+   MP_GT = 1
+} mp_ord;
+typedef enum {
+   MP_NO = 0,
+   MP_YES = 1
+} mp_bool;
+typedef enum {
+   MP_OKAY  = 0,
+   MP_ERR   = -1,
+   MP_MEM   = -2,
+   MP_VAL   = -3,
+   MP_RANGE = MP_VAL,
+   MP_ITER  = -4
+} mp_err;
+#else
+typedef int mp_sign;
+#define MP_ZPOS       0   /* positive integer */
+#define MP_NEG        1   /* negative */
+typedef int mp_ord;
+#define MP_LT        -1   /* less than */
+#define MP_EQ         0   /* equal to */
+#define MP_GT         1   /* greater than */
+typedef int mp_bool;
+#define MP_YES        1   /* yes response */
+#define MP_NO         0   /* no response */
+typedef int mp_err;
+#define MP_OKAY       0   /* ok result */
+#define MP_ERR        -1  /* unknown error */
+#define MP_MEM        -2  /* out of mem */
+#define MP_VAL        -3  /* invalid input */
+#define MP_RANGE      MP_VAL
+#define MP_ITER       -4  /* Max. iterations reached */
+#endif
 
 /* tunable cutoffs */
 
@@ -202,7 +224,8 @@ TOOM_SQR_CUTOFF;
 
 /* the infamous mp_int structure */
 typedef struct  {
-   int used, alloc, sign;
+   int used, alloc;
+   mp_sign sign;
    mp_digit *dp;
 } mp_int;
 
@@ -211,17 +234,17 @@ typedef int private_mp_prime_callback(unsigned char *dst, int len, void *dat);
 typedef private_mp_prime_callback ltm_prime_callback MP_DEPRECATED(mp_rand_source);
 
 /* error code to char* string */
-const char *mp_error_to_string(int code);
+const char *mp_error_to_string(mp_err code) MP_WUR;
 
 /* ---> init and deinit bignum functions <--- */
 /* init a bignum */
-MP_WUR int mp_init(mp_int *a);
+mp_err mp_init(mp_int *a) MP_WUR;
 
 /* free a bignum */
 void mp_clear(mp_int *a);
 
 /* init a null terminated series of arguments */
-MP_WUR int mp_init_multi(mp_int *mp, ...) MP_NULL_TERMINATED;
+mp_err mp_init_multi(mp_int *mp, ...) MP_NULL_TERMINATED MP_WUR;
 
 /* clear a null terminated series of arguments */
 void mp_clear_multi(mp_int *mp, ...) MP_NULL_TERMINATED;
@@ -230,18 +253,18 @@ void mp_clear_multi(mp_int *mp, ...) MP_NULL_TERMINATED;
 void mp_exch(mp_int *a, mp_int *b);
 
 /* shrink ram required for a bignum */
-MP_WUR int mp_shrink(mp_int *a);
+mp_err mp_shrink(mp_int *a) MP_WUR;
 
 /* grow an int to a given size */
-MP_WUR int mp_grow(mp_int *a, int size);
+mp_err mp_grow(mp_int *a, int size) MP_WUR;
 
 /* init to a given number of digits */
-MP_WUR int mp_init_size(mp_int *a, int size);
+mp_err mp_init_size(mp_int *a, int size) MP_WUR;
 
 /* ---> Basic Manipulations <--- */
 #define mp_iszero(a) (((a)->used == 0) ? MP_YES : MP_NO)
-MP_WUR int mp_iseven(const mp_int *a);
-MP_WUR int mp_isodd(const mp_int *a);
+mp_bool mp_iseven(const mp_int *a) MP_WUR;
+mp_bool mp_isodd(const mp_int *a) MP_WUR;
 #define mp_isneg(a)  (((a)->sign != MP_ZPOS) ? MP_YES : MP_NO)
 
 /* set to zero */
@@ -251,49 +274,49 @@ void mp_zero(mp_int *a);
 void mp_set(mp_int *a, mp_digit b);
 
 /* set a double */
-MP_WUR int mp_set_double(mp_int *a, double b);
+mp_err mp_set_double(mp_int *a, double b) MP_WUR;
 
 /* set a 32-bit const */
-/* TODO void - never fails */ int mp_set_int(mp_int *a, unsigned long b);
+/* TODO void - never fails */ mp_err mp_set_int(mp_int *a, unsigned long b);
 
 /* set a platform dependent unsigned long value */
-/* TODO void - never fails */ int mp_set_long(mp_int *a, unsigned long b);
+/* TODO void - never fails */ mp_err mp_set_long(mp_int *a, unsigned long b);
 
 /* set a platform dependent unsigned long long value */
-/* TODO void - never fails */ int mp_set_long_long(mp_int *a, unsigned long long b);
+/* TODO void - never fails */ mp_err mp_set_long_long(mp_int *a, unsigned long long b);
 
 /* get a double */
-MP_WUR double mp_get_double(const mp_int *a);
+double mp_get_double(const mp_int *a) MP_WUR;
 
 /* get a 32-bit value */
-MP_WUR unsigned long mp_get_int(const mp_int *a);
+unsigned long mp_get_int(const mp_int *a) MP_WUR;
 
 /* get a platform dependent unsigned long value */
-MP_WUR unsigned long mp_get_long(const mp_int *a);
+unsigned long mp_get_long(const mp_int *a) MP_WUR;
 
 /* get a platform dependent unsigned long long value */
-MP_WUR unsigned long long mp_get_long_long(const mp_int *a);
+unsigned long long mp_get_long_long(const mp_int *a) MP_WUR;
 
 /* initialize and set a digit */
-MP_WUR int mp_init_set(mp_int *a, mp_digit b);
+mp_err mp_init_set(mp_int *a, mp_digit b) MP_WUR;
 
 /* initialize and set 32-bit value */
-MP_WUR int mp_init_set_int(mp_int *a, unsigned long b);
+mp_err mp_init_set_int(mp_int *a, unsigned long b) MP_WUR;
 
 /* copy, b = a */
-MP_WUR int mp_copy(const mp_int *a, mp_int *b);
+mp_err mp_copy(const mp_int *a, mp_int *b) MP_WUR;
 
 /* inits and copies, a = b */
-MP_WUR int mp_init_copy(mp_int *a, const mp_int *b);
+mp_err mp_init_copy(mp_int *a, const mp_int *b) MP_WUR;
 
 /* trim unused digits */
 void mp_clamp(mp_int *a);
 
 /* import binary data */
-MP_WUR int mp_import(mp_int *rop, size_t count, int order, size_t size, int endian, size_t nails, const void *op);
+mp_err mp_import(mp_int *rop, size_t count, int order, size_t size, int endian, size_t nails, const void *op) MP_WUR;
 
 /* export binary data */
-MP_WUR int mp_export(void *rop, size_t *countp, int order, size_t size, int endian, size_t nails, const mp_int *op);
+mp_err mp_export(void *rop, size_t *countp, int order, size_t size, int endian, size_t nails, const mp_int *op) MP_WUR;
 
 /* ---> digit manipulation <--- */
 
@@ -301,37 +324,37 @@ MP_WUR int mp_export(void *rop, size_t *countp, int order, size_t size, int endi
 void mp_rshd(mp_int *a, int b);
 
 /* left shift by "b" digits */
-MP_WUR int mp_lshd(mp_int *a, int b);
+mp_err mp_lshd(mp_int *a, int b) MP_WUR;
 
 /* c = a / 2**b, implemented as c = a >> b */
-MP_WUR int mp_div_2d(const mp_int *a, int b, mp_int *c, mp_int *d);
+mp_err mp_div_2d(const mp_int *a, int b, mp_int *c, mp_int *d) MP_WUR;
 
 /* b = a/2 */
-MP_WUR int mp_div_2(const mp_int *a, mp_int *b);
+mp_err mp_div_2(const mp_int *a, mp_int *b) MP_WUR;
 
 /* c = a * 2**b, implemented as c = a << b */
-MP_WUR int mp_mul_2d(const mp_int *a, int b, mp_int *c);
+mp_err mp_mul_2d(const mp_int *a, int b, mp_int *c) MP_WUR;
 
 /* b = a*2 */
-MP_WUR int mp_mul_2(const mp_int *a, mp_int *b);
+mp_err mp_mul_2(const mp_int *a, mp_int *b) MP_WUR;
 
 /* c = a mod 2**b */
-MP_WUR int mp_mod_2d(const mp_int *a, int b, mp_int *c);
+mp_err mp_mod_2d(const mp_int *a, int b, mp_int *c) MP_WUR;
 
 /* computes a = 2**b */
-MP_WUR int mp_2expt(mp_int *a, int b);
+mp_err mp_2expt(mp_int *a, int b) MP_WUR;
 
 /* Counts the number of lsbs which are zero before the first zero bit */
-MP_WUR int mp_cnt_lsb(const mp_int *a);
+int mp_cnt_lsb(const mp_int *a) MP_WUR;
 
 /* I Love Earth! */
 
 /* makes a pseudo-random mp_int of a given size */
-MP_WUR int mp_rand(mp_int *a, int digits);
+mp_err mp_rand(mp_int *a, int digits) MP_WUR;
 /* makes a pseudo-random small int of a given size */
-MP_WUR MP_DEPRECATED(mp_rand) int mp_rand_digit(mp_digit *r);
+MP_DEPRECATED(mp_rand) mp_err mp_rand_digit(mp_digit *r) MP_WUR;
 /* use custom random data source instead of source provided the platform */
-void mp_rand_source(int source(void *out, size_t size));
+void mp_rand_source(mp_err source(void *out, size_t size));
 
 #ifdef MP_PRNG_ENABLE_LTM_RNG
 #  warning MP_PRNG_ENABLE_LTM_RNG has been deprecated, use mp_rand_source instead.
@@ -345,197 +368,197 @@ extern void (*ltm_rng_callback)(void);
 
 /* ---> binary operations <--- */
 /* c = a XOR b  */
-MP_WUR int mp_xor(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_xor(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a OR b */
-MP_WUR int mp_or(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_or(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a AND b */
-MP_WUR int mp_and(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_and(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* Checks the bit at position b and returns MP_YES
    if the bit is 1, MP_NO if it is 0 and MP_VAL
    in case of error */
-MP_WUR int mp_get_bit(const mp_int *a, int b);
+/* TODO better return type, mixes mp_bool and mp_err */ int mp_get_bit(const mp_int *a, int b) MP_WUR;
 
 /* c = a XOR b (two complement) */
-MP_WUR int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a OR b (two complement) */
-MP_WUR int mp_tc_or(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_tc_or(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a AND b (two complement) */
-MP_WUR int mp_tc_and(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_tc_and(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* right shift (two complement) */
-MP_WUR int mp_tc_div_2d(const mp_int *a, int b, mp_int *c);
+mp_err mp_tc_div_2d(const mp_int *a, int b, mp_int *c) MP_WUR;
 
 /* ---> Basic arithmetic <--- */
 
 /* b = ~a */
-MP_WUR int mp_complement(const mp_int *a, mp_int *b);
+mp_err mp_complement(const mp_int *a, mp_int *b) MP_WUR;
 
 /* b = -a */
-MP_WUR int mp_neg(const mp_int *a, mp_int *b);
+mp_err mp_neg(const mp_int *a, mp_int *b) MP_WUR;
 
 /* b = |a| */
-MP_WUR int mp_abs(const mp_int *a, mp_int *b);
+mp_err mp_abs(const mp_int *a, mp_int *b) MP_WUR;
 
 /* compare a to b */
-MP_WUR int mp_cmp(const mp_int *a, const mp_int *b);
+mp_ord mp_cmp(const mp_int *a, const mp_int *b) MP_WUR;
 
 /* compare |a| to |b| */
-MP_WUR int mp_cmp_mag(const mp_int *a, const mp_int *b);
+mp_ord mp_cmp_mag(const mp_int *a, const mp_int *b) MP_WUR;
 
 /* c = a + b */
-MP_WUR int mp_add(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a - b */
-MP_WUR int mp_sub(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_sub(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = a * b */
-MP_WUR int mp_mul(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* b = a*a  */
-MP_WUR int mp_sqr(const mp_int *a, mp_int *b);
+mp_err mp_sqr(const mp_int *a, mp_int *b) MP_WUR;
 
 /* a/b => cb + d == a */
-MP_WUR int mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d);
+mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d) MP_WUR;
 
 /* c = a mod b, 0 <= c < b  */
-MP_WUR int mp_mod(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_mod(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* ---> single digit functions <--- */
 
 /* compare against a single digit */
-MP_WUR int mp_cmp_d(const mp_int *a, mp_digit b);
+mp_ord mp_cmp_d(const mp_int *a, mp_digit b) MP_WUR;
 
 /* c = a + b */
-MP_WUR int mp_add_d(const mp_int *a, mp_digit b, mp_int *c);
+mp_err mp_add_d(const mp_int *a, mp_digit b, mp_int *c) MP_WUR;
 
 /* Increment "a" by one like "a++". Changes input! */
-MP_WUR int mp_incr(mp_int *a);
+mp_err mp_incr(mp_int *a) MP_WUR;
 
 /* c = a - b */
-MP_WUR int mp_sub_d(const mp_int *a, mp_digit b, mp_int *c);
+mp_err mp_sub_d(const mp_int *a, mp_digit b, mp_int *c) MP_WUR;
 
 /* Decrement "a" by one like "a--". Changes input! */
-MP_WUR int mp_decr(mp_int *a);
+mp_err mp_decr(mp_int *a) MP_WUR;
 
 /* c = a * b */
-MP_WUR int mp_mul_d(const mp_int *a, mp_digit b, mp_int *c);
+mp_err mp_mul_d(const mp_int *a, mp_digit b, mp_int *c) MP_WUR;
 
 /* a/b => cb + d == a */
-MP_WUR int mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d);
+mp_err mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d) MP_WUR;
 
 /* a/3 => 3c + d == a */
-MP_WUR int mp_div_3(const mp_int *a, mp_int *c, mp_digit *d);
+mp_err mp_div_3(const mp_int *a, mp_int *c, mp_digit *d) MP_WUR;
 
 /* c = a**b */
-MP_WUR int mp_expt_d(const mp_int *a, mp_digit b, mp_int *c);
-MP_WUR int mp_expt_d_ex(const mp_int *a, mp_digit b, mp_int *c, int fast);
+mp_err mp_expt_d(const mp_int *a, mp_digit b, mp_int *c) MP_WUR;
+mp_err mp_expt_d_ex(const mp_int *a, mp_digit b, mp_int *c, int fast) MP_WUR;
 
 /* c = a mod b, 0 <= c < b  */
-MP_WUR int mp_mod_d(const mp_int *a, mp_digit b, mp_digit *c);
+mp_err mp_mod_d(const mp_int *a, mp_digit b, mp_digit *c) MP_WUR;
 
 /* ---> number theory <--- */
 
 /* d = a + b (mod c) */
-MP_WUR int mp_addmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d);
+mp_err mp_addmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d) MP_WUR;
 
 /* d = a - b (mod c) */
-MP_WUR int mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d);
+mp_err mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d) MP_WUR;
 
 /* d = a * b (mod c) */
-MP_WUR int mp_mulmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d);
+mp_err mp_mulmod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d) MP_WUR;
 
 /* c = a * a (mod b) */
-MP_WUR int mp_sqrmod(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_sqrmod(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = 1/a (mod b) */
-MP_WUR int mp_invmod(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_invmod(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* c = (a, b) */
-MP_WUR int mp_gcd(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_gcd(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* produces value such that U1*a + U2*b = U3 */
-MP_WUR int mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3);
+mp_err mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3) MP_WUR;
 
 /* c = [a, b] or (a*b)/(a, b) */
-MP_WUR int mp_lcm(const mp_int *a, const mp_int *b, mp_int *c);
+mp_err mp_lcm(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
 
 /* finds one of the b'th root of a, such that |c|**b <= |a|
  *
  * returns error if a < 0 and b is even
  */
-MP_WUR int mp_n_root(const mp_int *a, mp_digit b, mp_int *c);
-MP_WUR int mp_n_root_ex(const mp_int *a, mp_digit b, mp_int *c, int fast);
+mp_err mp_n_root(const mp_int *a, mp_digit b, mp_int *c) MP_WUR;
+mp_err mp_n_root_ex(const mp_int *a, mp_digit b, mp_int *c, int fast) MP_WUR;
 
 /* special sqrt algo */
-MP_WUR int mp_sqrt(const mp_int *arg, mp_int *ret);
+mp_err mp_sqrt(const mp_int *arg, mp_int *ret) MP_WUR;
 
 /* special sqrt (mod prime) */
-MP_WUR int mp_sqrtmod_prime(const mp_int *n, const mp_int *prime, mp_int *ret);
+mp_err mp_sqrtmod_prime(const mp_int *n, const mp_int *prime, mp_int *ret) MP_WUR;
 
 /* is number a square? */
-MP_WUR int mp_is_square(const mp_int *arg, int *ret);
+mp_err mp_is_square(const mp_int *arg, mp_bool *ret) MP_WUR;
 
 /* computes the jacobi c = (a | n) (or Legendre if b is prime)  */
-MP_WUR int mp_jacobi(const mp_int *a, const mp_int *n, int *c);
+mp_err mp_jacobi(const mp_int *a, const mp_int *n, int *c) MP_WUR;
 
 /* computes the Kronecker symbol c = (a | p) (like jacobi() but with {a,p} in Z */
-MP_WUR int mp_kronecker(const mp_int *a, const mp_int *p, int *c);
+mp_err mp_kronecker(const mp_int *a, const mp_int *p, int *c) MP_WUR;
 
 /* used to setup the Barrett reduction for a given modulus b */
-MP_WUR int mp_reduce_setup(mp_int *a, const mp_int *b);
+mp_err mp_reduce_setup(mp_int *a, const mp_int *b) MP_WUR;
 
 /* Barrett Reduction, computes a (mod b) with a precomputed value c
  *
  * Assumes that 0 < x <= m*m, note if 0 > x > -(m*m) then you can merely
  * compute the reduction as -1 * mp_reduce(mp_abs(x)) [pseudo code].
  */
-MP_WUR int mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu);
+mp_err mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu) MP_WUR;
 
 /* setups the montgomery reduction */
-MP_WUR int mp_montgomery_setup(const mp_int *n, mp_digit *rho);
+mp_err mp_montgomery_setup(const mp_int *n, mp_digit *rho) MP_WUR;
 
 /* computes a = B**n mod b without division or multiplication useful for
  * normalizing numbers in a Montgomery system.
  */
-MP_WUR int mp_montgomery_calc_normalization(mp_int *a, const mp_int *b);
+mp_err mp_montgomery_calc_normalization(mp_int *a, const mp_int *b) MP_WUR;
 
 /* computes x/R == x (mod N) via Montgomery Reduction */
-MP_WUR int mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho);
+mp_err mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho) MP_WUR;
 
 /* returns 1 if a is a valid DR modulus */
-MP_WUR int mp_dr_is_modulus(const mp_int *a);
+mp_bool mp_dr_is_modulus(const mp_int *a) MP_WUR;
 
 /* sets the value of "d" required for mp_dr_reduce */
 void mp_dr_setup(const mp_int *a, mp_digit *d);
 
 /* reduces a modulo n using the Diminished Radix method */
-MP_WUR int mp_dr_reduce(mp_int *x, const mp_int *n, mp_digit k);
+mp_err mp_dr_reduce(mp_int *x, const mp_int *n, mp_digit k) MP_WUR;
 
 /* returns true if a can be reduced with mp_reduce_2k */
-MP_WUR int mp_reduce_is_2k(const mp_int *a);
+mp_bool mp_reduce_is_2k(const mp_int *a) MP_WUR;
 
 /* determines k value for 2k reduction */
-MP_WUR int mp_reduce_2k_setup(const mp_int *a, mp_digit *d);
+mp_err mp_reduce_2k_setup(const mp_int *a, mp_digit *d) MP_WUR;
 
 /* reduces a modulo b where b is of the form 2**p - k [0 <= a] */
-MP_WUR int mp_reduce_2k(mp_int *a, const mp_int *n, mp_digit d);
+mp_err mp_reduce_2k(mp_int *a, const mp_int *n, mp_digit d) MP_WUR;
 
 /* returns true if a can be reduced with mp_reduce_2k_l */
-MP_WUR int mp_reduce_is_2k_l(const mp_int *a);
+mp_bool mp_reduce_is_2k_l(const mp_int *a) MP_WUR;
 
 /* determines k value for 2k reduction */
-MP_WUR int mp_reduce_2k_setup_l(const mp_int *a, mp_int *d);
+mp_err mp_reduce_2k_setup_l(const mp_int *a, mp_int *d) MP_WUR;
 
 /* reduces a modulo b where b is of the form 2**p - k [0 <= a] */
-MP_WUR int mp_reduce_2k_l(mp_int *a, const mp_int *n, const mp_int *d);
+mp_err mp_reduce_2k_l(mp_int *a, const mp_int *n, const mp_int *d) MP_WUR;
 
 /* Y = G**X (mod P) */
-MP_WUR int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y);
+mp_err mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y) MP_WUR;
 
 /* ---> Primes <--- */
 
@@ -551,32 +574,32 @@ MP_WUR int mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int 
 extern const mp_digit ltm_prime_tab[MP_PRIME_SIZE];
 
 /* result=1 if a is divisible by one of the first MP_PRIME_SIZE primes */
-MP_WUR int mp_prime_is_divisible(const mp_int *a, int *result);
+mp_err mp_prime_is_divisible(const mp_int *a, mp_bool *result) MP_WUR;
 
 /* performs one Fermat test of "a" using base "b".
  * Sets result to 0 if composite or 1 if probable prime
  */
-MP_WUR int mp_prime_fermat(const mp_int *a, const mp_int *b, int *result);
+mp_err mp_prime_fermat(const mp_int *a, const mp_int *b, mp_bool *result) MP_WUR;
 
 /* performs one Miller-Rabin test of "a" using base "b".
  * Sets result to 0 if composite or 1 if probable prime
  */
-MP_WUR int mp_prime_miller_rabin(const mp_int *a, const mp_int *b, int *result);
+mp_err mp_prime_miller_rabin(const mp_int *a, const mp_int *b, mp_bool *result) MP_WUR;
 
 /* This gives [for a given bit size] the number of trials required
  * such that Miller-Rabin gives a prob of failure lower than 2^-96
  */
-MP_WUR int mp_prime_rabin_miller_trials(int size);
+int mp_prime_rabin_miller_trials(int size) MP_WUR;
 
 /* performs one strong Lucas-Selfridge test of "a".
  * Sets result to 0 if composite or 1 if probable prime
  */
-MP_WUR int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result);
+mp_err mp_prime_strong_lucas_selfridge(const mp_int *a, mp_bool *result) MP_WUR;
 
 /* performs one Frobenius test of "a" as described by Paul Underwood.
  * Sets result to 0 if composite or 1 if probable prime
  */
-MP_WUR int mp_prime_frobenius_underwood(const mp_int *N, int *result);
+mp_err mp_prime_frobenius_underwood(const mp_int *N, mp_bool *result) MP_WUR;
 
 /* performs t random rounds of Miller-Rabin on "a" additional to
  * bases 2 and 3.  Also performs an initial sieve of trial
@@ -592,14 +615,14 @@ MP_WUR int mp_prime_frobenius_underwood(const mp_int *N, int *result);
  *
  * Sets result to 1 if probably prime, 0 otherwise
  */
-MP_WUR int mp_prime_is_prime(const mp_int *a, int t, int *result);
+mp_err mp_prime_is_prime(const mp_int *a, int t, mp_bool *result) MP_WUR;
 
 /* finds the next prime after the number "a" using "t" trials
  * of Miller-Rabin.
  *
  * bbs_style = 1 means the prime must be congruent to 3 mod 4
  */
-MP_WUR int mp_prime_next_prime(mp_int *a, int t, int bbs_style);
+mp_err mp_prime_next_prime(mp_int *a, int t, int bbs_style) MP_WUR;
 
 /* makes a truly random prime of a given size (bytes),
  * call with bbs = 1 if you want it to be congruent to 3 mod 4
@@ -625,35 +648,34 @@ MP_WUR int mp_prime_next_prime(mp_int *a, int t, int bbs_style);
  * so it can be NULL
  *
  */
-MP_WUR MP_DEPRECATED(mp_prime_rand) int mp_prime_random_ex(mp_int *a, int t, int size, int flags,
-      private_mp_prime_callback cb, void *dat);
-MP_WUR int mp_prime_rand(mp_int *a, int t, int size, int flags);
+MP_DEPRECATED(mp_prime_rand) mp_err mp_prime_random_ex(mp_int *a, int t, int size, int flags,
+      private_mp_prime_callback cb, void *dat) MP_WUR;
+mp_err mp_prime_rand(mp_int *a, int t, int size, int flags) MP_WUR;
 
 /* Integer logarithm to integer base */
-MP_WUR int mp_ilogb(const mp_int *a, mp_digit base, mp_int *c);
-
+mp_err mp_ilogb(const mp_int *a, mp_digit base, mp_int *c) MP_WUR;
 
 /* ---> radix conversion <--- */
-MP_WUR int mp_count_bits(const mp_int *a);
+int mp_count_bits(const mp_int *a) MP_WUR;
 
-MP_WUR int mp_unsigned_bin_size(const mp_int *a);
-MP_WUR int mp_read_unsigned_bin(mp_int *a, const unsigned char *b, int c);
-MP_WUR int mp_to_unsigned_bin(const mp_int *a, unsigned char *b);
-MP_WUR int mp_to_unsigned_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen);
+int mp_unsigned_bin_size(const mp_int *a) MP_WUR;
+mp_err mp_read_unsigned_bin(mp_int *a, const unsigned char *b, int c) MP_WUR;
+mp_err mp_to_unsigned_bin(const mp_int *a, unsigned char *b) MP_WUR;
+mp_err mp_to_unsigned_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen) MP_WUR;
 
-MP_WUR int mp_signed_bin_size(const mp_int *a);
-MP_WUR int mp_read_signed_bin(mp_int *a, const unsigned char *b, int c);
-MP_WUR int mp_to_signed_bin(const mp_int *a,  unsigned char *b);
-MP_WUR int mp_to_signed_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen);
+int mp_signed_bin_size(const mp_int *a) MP_WUR;
+mp_err mp_read_signed_bin(mp_int *a, const unsigned char *b, int c) MP_WUR;
+mp_err mp_to_signed_bin(const mp_int *a,  unsigned char *b) MP_WUR;
+mp_err mp_to_signed_bin_n(const mp_int *a, unsigned char *b, unsigned long *outlen) MP_WUR;
 
-MP_WUR int mp_read_radix(mp_int *a, const char *str, int radix);
-MP_WUR int mp_toradix(const mp_int *a, char *str, int radix);
-MP_WUR int mp_toradix_n(const mp_int *a, char *str, int radix, int maxlen);
-MP_WUR int mp_radix_size(const mp_int *a, int radix, int *size);
+mp_err mp_read_radix(mp_int *a, const char *str, int radix) MP_WUR;
+mp_err mp_toradix(const mp_int *a, char *str, int radix) MP_WUR;
+mp_err mp_toradix_n(const mp_int *a, char *str, int radix, int maxlen) MP_WUR;
+mp_err mp_radix_size(const mp_int *a, int radix, int *size) MP_WUR;
 
 #ifndef MP_NO_FILE
-MP_WUR int mp_fread(mp_int *a, int radix, FILE *stream);
-MP_WUR int mp_fwrite(const mp_int *a, int radix, FILE *stream);
+mp_err mp_fread(mp_int *a, int radix, FILE *stream) MP_WUR;
+mp_err mp_fwrite(const mp_int *a, int radix, FILE *stream) MP_WUR;
 #endif
 
 #define mp_read_raw(mp, str, len) (MP_DEPRECATED_PRAGMA("replaced by mp_read_signed_bin") mp_read_signed_bin((mp), (str), (len)))
diff --git a/tommath_private.h b/tommath_private.h
index 7716dce..9e052ce 100644
--- a/tommath_private.h
+++ b/tommath_private.h
@@ -142,31 +142,31 @@ extern void MP_FREE(void *mem, size_t size);
 #define MP_MAXFAST              (int)(1uL << (MP_SIZEOF_BITS(mp_word) - (2u * (size_t)MP_DIGIT_BIT)))
 
 /* random number source */
-extern int (*s_mp_rand_source)(void *out, size_t size);
+extern mp_err(*s_mp_rand_source)(void *out, size_t size);
 
 /* Minimum number of available digits in mp_int, MP_PREC >= MP_MIN_PREC */
 #define MP_MIN_PREC ((((CHAR_BIT * (int)sizeof(long long)) + MP_DIGIT_BIT) - 1) / MP_DIGIT_BIT)
 
 /* lowlevel functions, do not call! */
-MP_WUR int s_mp_add(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs);
-MP_WUR int s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs);
-MP_WUR int s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs);
-MP_WUR int s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs);
-MP_WUR int s_mp_sqr_fast(const mp_int *a, mp_int *b);
-MP_WUR int s_mp_sqr(const mp_int *a, mp_int *b);
-MP_WUR int s_mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_karatsuba_sqr(const mp_int *a, mp_int *b);
-MP_WUR int s_mp_toom_sqr(const mp_int *a, mp_int *b);
-MP_WUR int s_mp_invmod_fast(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c);
-MP_WUR int s_mp_montgomery_reduce_fast(mp_int *x, const mp_int *n, mp_digit rho);
-MP_WUR int s_mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode);
-MP_WUR int s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode);
-MP_WUR int s_mp_rand_platform(void *p, size_t n);
+mp_err s_mp_add(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs) MP_WUR;
+mp_err s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs) MP_WUR;
+mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs) MP_WUR;
+mp_err s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs) MP_WUR;
+mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b) MP_WUR;
+mp_err s_mp_sqr(const mp_int *a, mp_int *b) MP_WUR;
+mp_err s_mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_karatsuba_sqr(const mp_int *a, mp_int *b) MP_WUR;
+mp_err s_mp_toom_sqr(const mp_int *a, mp_int *b) MP_WUR;
+mp_err s_mp_invmod_fast(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c) MP_WUR;
+mp_err s_mp_montgomery_reduce_fast(mp_int *x, const mp_int *n, mp_digit rho) MP_WUR;
+mp_err s_mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode) MP_WUR;
+mp_err s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode) MP_WUR;
+mp_err s_mp_rand_platform(void *p, size_t n) MP_WUR;
 void s_mp_reverse(unsigned char *s, int len);
 
 /* TODO: jenkins prng is not thread safe as of now */
@@ -198,20 +198,20 @@ int func_name (mp_int * a, type b)                       \
 }
 
 /* deprecated functions */
-MP_DEPRECATED(s_mp_invmod_fast) int fast_mp_invmod(const mp_int *a, const mp_int *b, mp_int *c);
-MP_DEPRECATED(s_mp_montgomery_reduce_fast) int fast_mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho);
-MP_DEPRECATED(s_mp_mul_digs_fast) int fast_s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs);
-MP_DEPRECATED(s_mp_mul_high_digs_fast) int fast_s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c,
+MP_DEPRECATED(s_mp_invmod_fast) mp_err fast_mp_invmod(const mp_int *a, const mp_int *b, mp_int *c);
+MP_DEPRECATED(s_mp_montgomery_reduce_fast) mp_err fast_mp_montgomery_reduce(mp_int *x, const mp_int *n, mp_digit rho);
+MP_DEPRECATED(s_mp_mul_digs_fast) mp_err fast_s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs);
+MP_DEPRECATED(s_mp_mul_high_digs_fast) mp_err fast_s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c,
       int digs);
-MP_DEPRECATED(s_mp_sqr_fast) int fast_s_mp_sqr(const mp_int *a, mp_int *b);
-MP_DEPRECATED(s_mp_balance_mul) int mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_DEPRECATED(s_mp_exptmod_fast) int mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y,
+MP_DEPRECATED(s_mp_sqr_fast) mp_err fast_s_mp_sqr(const mp_int *a, mp_int *b);
+MP_DEPRECATED(s_mp_balance_mul) mp_err mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c);
+MP_DEPRECATED(s_mp_exptmod_fast) mp_err mp_exptmod_fast(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y,
       int redmode);
-MP_DEPRECATED(s_mp_invmod_slow) int mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c);
-MP_DEPRECATED(s_mp_karatsuba_mul) int mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_DEPRECATED(s_mp_karatsuba_sqr) int mp_karatsuba_sqr(const mp_int *a, mp_int *b);
-MP_DEPRECATED(s_mp_toom_mul) int mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c);
-MP_DEPRECATED(s_mp_toom_sqr) int mp_toom_sqr(const mp_int *a, mp_int *b);
+MP_DEPRECATED(s_mp_invmod_slow) mp_err mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c);
+MP_DEPRECATED(s_mp_karatsuba_mul) mp_err mp_karatsuba_mul(const mp_int *a, const mp_int *b, mp_int *c);
+MP_DEPRECATED(s_mp_karatsuba_sqr) mp_err mp_karatsuba_sqr(const mp_int *a, mp_int *b);
+MP_DEPRECATED(s_mp_toom_mul) mp_err mp_toom_mul(const mp_int *a, const mp_int *b, mp_int *c);
+MP_DEPRECATED(s_mp_toom_sqr) mp_err mp_toom_sqr(const mp_int *a, mp_int *b);
 MP_DEPRECATED(s_mp_reverse) void bn_reverse(unsigned char *s, int len);
 
 #ifdef __cplusplus