kc3-lang/libtommath/bn_mp_rand.c

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• Hash : 9ddf1e58
  Author :
  Date : 2019-05-07T12:26:46
  

  support custom random data source via mp_rand_source * deprecate MP_PRNG_ENABLE_LTM_RNG * custom mp_rand_source is used always if set, which should be more aligned with user expectations * use custom source in tune.c * don't call random number generator once per digit, which is slow

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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
  #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(void *p, size_t n)
  {
     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 MP_ERR;
        }
        atexit(s_cleanup_win_csp);
     }
     return CryptGenRandom(hProv, (DWORD)n, (BYTE *)p) == TRUE ? MP_OKAY : MP_ERR;
  }
  #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(void *p, size_t n)
  {
     char *q = (char *)p;
     while (n > 0) {
        ssize_t ret = getrandom(q, n, 0);
        if (ret < 0) {
           if (errno == EINTR) {
              continue;
           }
           return MP_ERR;
        }
        q += ret;
        n -= (size_t)ret;
     }
     return MP_OKAY;
  }
  #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(void *p, size_t n)
  {
     int fd;
     char *q = (char *)p;
  
     do {
        fd = open(MP_DEV_URANDOM, O_RDONLY);
     } while ((fd == -1) && (errno == EINTR));
     if (fd == -1) return MP_ERR;
  
     while (n > 0) {
        ssize_t ret = read(fd, p, n);
        if (ret < 0) {
           if (errno == EINTR) {
              continue;
           }
           close(fd);
           return MP_ERR;
        }
        q += ret;
        n -= (size_t)ret;
     }
  
     close(fd);
     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(void *p, size_t n)
  {
     unsigned long ret;
     if (ltm_rng == NULL) return MP_ERR;
     ret = ltm_rng(p, n, ltm_rng_callback);
     if (ret != n) return MP_ERR;
     return MP_OKAY;
  }
  #endif
  
  static int s_mp_rand_source_platform(void *p, size_t n)
  {
     int ret = MP_ERR;
  
  #if defined(MP_ARC4RANDOM)
     arc4random_buf(p, n);
     return MP_OKAY;
  #endif
  
  #if defined(MP_WIN_CSP)
     ret = s_read_win_csp(p, n);
     if (ret == MP_OKAY) return ret;
  #else
  
  #if defined(MP_GETRANDOM)
     ret = s_read_getrandom(p, n);
     if (ret == MP_OKAY) return ret;
  #endif
  #if defined(MP_DEV_URANDOM)
     ret = s_read_dev_urandom(p, n);
     if (ret == MP_OKAY) return ret;
  #endif
  
  #endif /* MP_WIN_CSP */
  
  #if defined(MP_PRNG_ENABLE_LTM_RNG)
     ret = s_read_ltm_rng(p, n);
     if (ret == MP_OKAY) return ret;
  #endif
  
     return ret;
  }
  
  static int (*s_rand_source)(void *, size_t) = s_mp_rand_source_platform;
  
  void mp_rand_source(int (*get)(void *out, size_t size))
  {
     s_rand_source = get;
  }
  
  /* makes a pseudo-random int of a given size */
  int mp_rand_digit(mp_digit *r)
  {
     int ret = s_rand_source(r, sizeof(mp_digit));
     *r &= MP_MASK;
     return ret;
  }
  
  int mp_rand(mp_int *a, int digits)
  {
     int ret, i;
  
     mp_zero(a);
  
     if (digits <= 0) {
        return MP_OKAY;
     }
  
     if ((ret = mp_grow(a, digits)) != MP_OKAY) {
        return ret;
     }
  
     if ((ret = s_rand_source(a->dp, (size_t)digits * sizeof(mp_digit))) != MP_OKAY) {
        return ret;
     }
  
     /* TODO: We ensure that the highest digit is nonzero. Should this be removed? */
     while ((a->dp[digits - 1] & MP_MASK) == 0) {
        if ((ret = s_rand_source(a->dp + digits - 1, sizeof(mp_digit))) != MP_OKAY) {
           return ret;
        }
     }
  
     a->used = digits;
     for (i = 0; i < digits; ++i) {
        a->dp[i] &= MP_MASK;
     }
  
     mp_clamp(a);
     return MP_OKAY;
  }
  #endif
  

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