Import code from previous AssetBuilder version

thirdparty/libtomcrypt/math/rand_prime.c

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+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+#include "tomcrypt.h"
+
+#if defined(LTC_MRSA) || (!defined(LTC_NO_MATH) && !defined(LTC_NO_PRNGS))
+
+/**
+  @file rand_prime.c
+  Generate a random prime, Tom St Denis
+*/
+
+#define USE_BBS 1
+
+int rand_prime(void *N, long len, prng_state *prng, int wprng)
+{
+   int            err, res, type;
+   unsigned char *buf;
+
+   LTC_ARGCHK(N != NULL);
+
+   /* get type */
+   if (len < 0) {
+      type = USE_BBS;
+      len = -len;
+   } else {
+      type = 0;
+   }
+
+   /* allow sizes between 2 and 512 bytes for a prime size */
+   if (len < 2 || len > 512) {
+      return CRYPT_INVALID_PRIME_SIZE;
+   }
+
+   /* valid PRNG? Better be! */
+   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
+      return err;
+   }
+
+   /* allocate buffer to work with */
+   buf = XCALLOC(1, len);
+   if (buf == NULL) {
+       return CRYPT_MEM;
+   }
+
+   do {
+      /* generate value */
+      if (prng_descriptor[wprng].read(buf, len, prng) != (unsigned long)len) {
+         XFREE(buf);
+         return CRYPT_ERROR_READPRNG;
+      }
+
+      /* munge bits */
+      buf[0]     |= 0x80 | 0x40;
+      buf[len-1] |= 0x01 | ((type & USE_BBS) ? 0x02 : 0x00);
+
+      /* load value */
+      if ((err = mp_read_unsigned_bin(N, buf, len)) != CRYPT_OK) {
+         XFREE(buf);
+         return err;
+      }
+
+      /* test */
+      if ((err = mp_prime_is_prime(N, LTC_MILLER_RABIN_REPS, &res)) != CRYPT_OK) {
+         XFREE(buf);
+         return err;
+      }
+   } while (res == LTC_MP_NO);
+
+#ifdef LTC_CLEAN_STACK
+   zeromem(buf, len);
+#endif
+
+   XFREE(buf);
+   return CRYPT_OK;
+}
+
+#endif /* LTC_NO_MATH */
+
+
+/* ref:         HEAD -> master, tag: v1.18.2 */
+/* git commit:  7e7eb695d581782f04b24dc444cbfde86af59853 */
+/* commit time: 2018-07-01 22:49:01 +0200 */