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