| // SPDX-License-Identifier: BSD-2-Clause |
| /* 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_private.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: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |