| // 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" |
| |
| #ifdef LTC_RNG_MAKE_PRNG |
| /** |
| @file rng_make_prng.c |
| portable way to get secure random bits to feed a PRNG (Tom St Denis) |
| */ |
| |
| /** |
| Create a PRNG from a RNG |
| |
| In case you pass bits as '-1' the PRNG will be setup |
| as if the export/import functionality has been used, |
| but the imported data comes directly from the RNG. |
| |
| @param bits Number of bits of entropy desired (-1 or 64 ... 1024) |
| @param wprng Index of which PRNG to setup |
| @param prng [out] PRNG state to initialize |
| @param callback A pointer to a void function for when the RNG is slow, this can be NULL |
| @return CRYPT_OK if successful |
| */ |
| int rng_make_prng(int bits, int wprng, prng_state *prng, |
| void (*callback)(void)) |
| { |
| unsigned char* buf; |
| unsigned long bytes; |
| int err; |
| |
| LTC_ARGCHK(prng != NULL); |
| |
| /* check parameter */ |
| if ((err = prng_is_valid(wprng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| if (bits == -1) { |
| bytes = prng_descriptor[wprng]->export_size; |
| } else if (bits < 64 || bits > 1024) { |
| return CRYPT_INVALID_PRNGSIZE; |
| } else { |
| bytes = (unsigned long)((bits+7)/8) * 2; |
| } |
| |
| if ((err = prng_descriptor[wprng]->start(prng)) != CRYPT_OK) { |
| return err; |
| } |
| |
| buf = XMALLOC(bytes); |
| if (buf == NULL) { |
| return CRYPT_MEM; |
| } |
| |
| if (rng_get_bytes(buf, bytes, callback) != bytes) { |
| err = CRYPT_ERROR_READPRNG; |
| goto LBL_ERR; |
| } |
| |
| if (bits == -1) { |
| if ((err = prng_descriptor[wprng]->pimport(buf, bytes, prng)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| } else { |
| if ((err = prng_descriptor[wprng]->add_entropy(buf, bytes, prng)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| } |
| if ((err = prng_descriptor[wprng]->ready(prng)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| |
| LBL_ERR: |
| #ifdef LTC_CLEAN_STACK |
| zeromem(buf, bytes); |
| #endif |
| XFREE(buf); |
| return err; |
| } |
| #endif /* #ifdef LTC_RNG_MAKE_PRNG */ |
| |
| |
| /* ref: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |