| /* 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. |
| * |
| * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org |
| */ |
| /* portable way to get secure random bits to feed a PRNG */ |
| #include "mycrypt.h" |
| |
| int rng_make_prng(int bits, int wprng, prng_state *prng, |
| void (*callback)(void)) |
| { |
| unsigned char buf[256]; |
| int err; |
| |
| _ARGCHK(prng != NULL); |
| |
| /* check parameter */ |
| if ((err = prng_is_valid(wprng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| if (bits < 64 || bits > 1024) { |
| return CRYPT_INVALID_PRNGSIZE; |
| } |
| |
| if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| bits = ((bits/8)+((bits&7)!=0?1:0)) * 2; |
| if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) { |
| return CRYPT_ERROR_READPRNG; |
| } |
| |
| if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| #ifdef CLEAN_STACK |
| zeromem(buf, sizeof(buf)); |
| #endif |
| return CRYPT_OK; |
| } |
| |