kc3-lang/libtommath/bn_mp_rand.c

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• Hash : ff561404
  Author :
  Date : 2019-04-07T15:29:11
  

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• bn_mp_rand.c

• #include "tommath_private.h"
  #ifdef BN_MP_RAND_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* First the OS-specific special cases
   * - *BSD
   * - Windows
   */
  #if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
  #define MP_ARC4RANDOM
  #define MP_GEN_RANDOM_MAX     0xffffffffu
  #define MP_GEN_RANDOM_SHIFT   32
  
  static int s_read_arc4random(mp_digit *p)
  {
     mp_digit d = 0, msk = 0;
     do {
        d <<= MP_GEN_RANDOM_SHIFT;
        d |= ((mp_digit) arc4random());
        msk <<= MP_GEN_RANDOM_SHIFT;
        msk |= (MP_MASK & MP_GEN_RANDOM_MAX);
     } while ((MP_MASK & msk) != MP_MASK);
     *p = d;
     return MP_OKAY;
  }
  #endif
  
  #if defined(_WIN32) || defined(_WIN32_WCE)
  #define MP_WIN_CSP
  
  #ifndef _WIN32_WINNT
  #define _WIN32_WINNT 0x0400
  #endif
  #ifdef _WIN32_WCE
  #define UNDER_CE
  #define ARM
  #endif
  
  #define WIN32_LEAN_AND_MEAN
  #include <windows.h>
  #include <wincrypt.h>
  
  static HCRYPTPROV hProv = 0;
  
  static void s_cleanup_win_csp(void)
  {
     CryptReleaseContext(hProv, 0);
     hProv = 0;
  }
  
  static int s_read_win_csp(mp_digit *p)
  {
     int ret = -1;
     if (hProv == 0) {
        if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
                                 (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
            !CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
                                 CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) {
           hProv = 0;
           return ret;
        }
        atexit(s_cleanup_win_csp);
     }
     if (CryptGenRandom(hProv, sizeof(*p), (void *)p) == TRUE) {
        ret = MP_OKAY;
     }
     return ret;
  }
  #endif /* WIN32 */
  
  #if !defined(MP_WIN_CSP) && defined(__linux__) && defined(__GLIBC_PREREQ)
  #if __GLIBC_PREREQ(2, 25)
  #define MP_GETRANDOM
  #include <sys/random.h>
  #include <errno.h>
  
  static int s_read_getrandom(mp_digit *p)
  {
     ssize_t ret;
     do {
        ret = getrandom(p, sizeof(*p), 0);
     } while ((ret == -1) && (errno == EINTR));
     if (ret == sizeof(*p)) return MP_OKAY;
     return -1;
  }
  #endif
  #endif
  
  /* We assume all platforms besides windows provide "/dev/urandom".
   * In case yours doesn't, define MP_NO_DEV_URANDOM at compile-time.
   */
  #if !defined(MP_WIN_CSP) && !defined(MP_NO_DEV_URANDOM)
  #ifndef MP_DEV_URANDOM
  #define MP_DEV_URANDOM "/dev/urandom"
  #endif
  #include <fcntl.h>
  #include <errno.h>
  #include <unistd.h>
  
  static int s_read_dev_urandom(mp_digit *p)
  {
     ssize_t r;
     int fd;
     do {
        fd = open(MP_DEV_URANDOM, O_RDONLY);
     } while ((fd == -1) && (errno == EINTR));
     if (fd == -1) return -1;
     do {
        r = read(fd, p, sizeof(*p));
     } while ((r == -1) && (errno == EINTR));
     close(fd);
     if (r != sizeof(*p)) return -1;
     return MP_OKAY;
  }
  #endif
  
  #if defined(MP_PRNG_ENABLE_LTM_RNG)
  unsigned long (*ltm_rng)(unsigned char *out, unsigned long outlen, void (*callback)(void));
  void (*ltm_rng_callback)(void);
  
  static int s_read_ltm_rng(mp_digit *p)
  {
     unsigned long ret;
     if (ltm_rng == NULL) return -1;
     ret = ltm_rng((void *)p, sizeof(*p), ltm_rng_callback);
     if (ret != sizeof(*p)) return -1;
     return MP_OKAY;
  }
  #endif
  
  static int s_rand_digit(mp_digit *p)
  {
     int ret = -1;
  
  #if defined(MP_ARC4RANDOM)
     ret = s_read_arc4random(p);
     if (ret == MP_OKAY) return ret;
  #endif
  
  #if defined(MP_WIN_CSP)
     ret = s_read_win_csp(p);
     if (ret == MP_OKAY) return ret;
  #else
  
  #if defined(MP_GETRANDOM)
     ret = s_read_getrandom(p);
     if (ret == MP_OKAY) return ret;
  #endif
  #if defined(MP_DEV_URANDOM)
     ret = s_read_dev_urandom(p);
     if (ret == MP_OKAY) return ret;
  #endif
  
  #endif /* MP_WIN_CSP */
  
  #if defined(MP_PRNG_ENABLE_LTM_RNG)
     ret = s_read_ltm_rng(p);
     if (ret == MP_OKAY) return ret;
  #endif
  
     return ret;
  }
  
  /* makes a pseudo-random int of a given size */
  int mp_rand_digit(mp_digit *r)
  {
     int ret = s_rand_digit(r);
     *r &= MP_MASK;
     return ret;
  }
  
  int mp_rand(mp_int *a, int digits)
  {
     int     res;
     mp_digit d;
  
     mp_zero(a);
     if (digits <= 0) {
        return MP_OKAY;
     }
  
     /* first place a random non-zero digit */
     do {
        if (mp_rand_digit(&d) != MP_OKAY) {
           return MP_VAL;
        }
     } while (d == 0u);
  
     if ((res = mp_add_d(a, d, a)) != MP_OKAY) {
        return res;
     }
  
     while (--digits > 0) {
        if ((res = mp_lshd(a, 1)) != MP_OKAY) {
           return res;
        }
  
        if (mp_rand_digit(&d) != MP_OKAY) {
           return MP_VAL;
        }
        if ((res = mp_add_d(a, d, a)) != MP_OKAY) {
           return res;
        }
     }
  
     return MP_OKAY;
  }
  #endif
  

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