--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_s_mp_rand_platform.c	Tue May 26 17:36:47 2020 +0200
@@ -0,0 +1,148 @@
+#include "tommath_private.h"
+#ifdef BN_S_MP_RAND_PLATFORM_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 BN_S_READ_ARC4RANDOM_C
+static mp_err s_read_arc4random(void *p, size_t n)
+{
+   arc4random_buf(p, n);
+   return MP_OKAY;
+}
+#endif
+
+#if defined(_WIN32) || defined(_WIN32_WCE)
+#define BN_S_READ_WINCSP_C
+
+#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 mp_err s_read_wincsp(void *p, size_t n)
+{
+   static HCRYPTPROV hProv = 0;
+   if (hProv == 0) {
+      HCRYPTPROV h = 0;
+      if (!CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+                               (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
+          !CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+                               CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) {
+         return MP_ERR;
+      }
+      hProv = h;
+   }
+   return CryptGenRandom(hProv, (DWORD)n, (BYTE *)p) == TRUE ? MP_OKAY : MP_ERR;
+}
+#endif /* WIN32 */
+
+#if !defined(BN_S_READ_WINCSP_C) && defined(__linux__) && defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 25)
+#define BN_S_READ_GETRANDOM_C
+#include <sys/random.h>
+#include <errno.h>
+
+static mp_err s_read_getrandom(void *p, size_t n)
+{
+   char *q = (char *)p;
+   while (n > 0u) {
+      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(BN_S_READ_WINCSP_C) && !defined(MP_NO_DEV_URANDOM)
+#define BN_S_READ_URANDOM_C
+#ifndef MP_DEV_URANDOM
+#define MP_DEV_URANDOM "/dev/urandom"
+#endif
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
+static mp_err s_read_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 > 0u) {
+      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)
+#define BN_S_READ_LTM_RNG
+unsigned long (*ltm_rng)(unsigned char *out, unsigned long outlen, void (*callback)(void));
+void (*ltm_rng_callback)(void);
+
+static mp_err s_read_ltm_rng(void *p, size_t n)
+{
+   unsigned long res;
+   if (ltm_rng == NULL) return MP_ERR;
+   res = ltm_rng(p, n, ltm_rng_callback);
+   if (res != n) return MP_ERR;
+   return MP_OKAY;
+}
+#endif
+
+mp_err s_read_arc4random(void *p, size_t n);
+mp_err s_read_wincsp(void *p, size_t n);
+mp_err s_read_getrandom(void *p, size_t n);
+mp_err s_read_urandom(void *p, size_t n);
+mp_err s_read_ltm_rng(void *p, size_t n);
+
+mp_err s_mp_rand_platform(void *p, size_t n)
+{
+   mp_err err = MP_ERR;
+   if ((err != MP_OKAY) && MP_HAS(S_READ_ARC4RANDOM)) err = s_read_arc4random(p, n);
+   if ((err != MP_OKAY) && MP_HAS(S_READ_WINCSP))     err = s_read_wincsp(p, n);
+   if ((err != MP_OKAY) && MP_HAS(S_READ_GETRANDOM))  err = s_read_getrandom(p, n);
+   if ((err != MP_OKAY) && MP_HAS(S_READ_URANDOM))    err = s_read_urandom(p, n);
+   if ((err != MP_OKAY) && MP_HAS(S_READ_LTM_RNG))    err = s_read_ltm_rng(p, n);
+   return err;
+}
+
+#endif