diff options
Diffstat (limited to 'lib/bt/common/tinycrypt/src/hmac_prng.c')
| -rw-r--r-- | lib/bt/common/tinycrypt/src/hmac_prng.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/lib/bt/common/tinycrypt/src/hmac_prng.c b/lib/bt/common/tinycrypt/src/hmac_prng.c new file mode 100644 index 00000000..1e3a52fb --- /dev/null +++ b/lib/bt/common/tinycrypt/src/hmac_prng.c @@ -0,0 +1,218 @@ +/* + * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD + * + * SPDX-License-Identifier: Apache-2.0 + */ + +/* + * Copyright (C) 2017 by Intel Corporation, All Rights Reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * - Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * - Neither the name of Intel Corporation nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +/* hmac_prng.c - TinyCrypt implementation of HMAC-PRNG */ + +#include <tinycrypt/hmac_prng.h> +#include <tinycrypt/hmac.h> +#include <tinycrypt/constants.h> +#include <tinycrypt/utils.h> + +/* + * min bytes in the seed string. + * MIN_SLEN*8 must be at least the expected security level. + */ +static const unsigned int MIN_SLEN = 32; + +/* + * max bytes in the seed string; + * SP800-90A specifies a maximum of 2^35 bits (i.e., 2^32 bytes). + */ +static const unsigned int MAX_SLEN = UINT32_MAX; + +/* + * max bytes in the personalization string; + * SP800-90A specifies a maximum of 2^35 bits (i.e., 2^32 bytes). + */ +static const unsigned int MAX_PLEN = UINT32_MAX; + +/* + * max bytes in the additional_info string; + * SP800-90A specifies a maximum of 2^35 bits (i.e., 2^32 bytes). + */ +static const unsigned int MAX_ALEN = UINT32_MAX; + +/* + * max number of generates between re-seeds; + * TinyCrypt accepts up to (2^32 - 1) which is the maximal value of + * a 32-bit unsigned int variable, while SP800-90A specifies a maximum of 2^48. + */ +static const unsigned int MAX_GENS = UINT32_MAX; + +/* + * maximum bytes per generate call; + * SP800-90A specifies a maximum up to 2^19. + */ +static const unsigned int MAX_OUT = (1 << 19); + +/* + * Assumes: prng != NULL, e != NULL, len >= 0. + */ +static void update(TCHmacPrng_t prng, const uint8_t *e, unsigned int len) +{ + const uint8_t separator0 = 0x00; + const uint8_t separator1 = 0x01; + + /* use current state, e and separator 0 to compute a new prng key: */ + (void)tc_hmac_init(&prng->h); + (void)tc_hmac_update(&prng->h, prng->v, sizeof(prng->v)); + (void)tc_hmac_update(&prng->h, &separator0, sizeof(separator0)); + (void)tc_hmac_update(&prng->h, e, len); + (void)tc_hmac_final(prng->key, sizeof(prng->key), &prng->h); + /* configure the new prng key into the prng's instance of hmac */ + (void)tc_hmac_set_key(&prng->h, prng->key, sizeof(prng->key)); + + /* use the new key to compute a new state variable v */ + (void)tc_hmac_init(&prng->h); + (void)tc_hmac_update(&prng->h, prng->v, sizeof(prng->v)); + (void)tc_hmac_final(prng->v, sizeof(prng->v), &prng->h); + + /* use current state, e and separator 1 to compute a new prng key: */ + (void)tc_hmac_init(&prng->h); + (void)tc_hmac_update(&prng->h, prng->v, sizeof(prng->v)); + (void)tc_hmac_update(&prng->h, &separator1, sizeof(separator1)); + (void)tc_hmac_update(&prng->h, e, len); + (void)tc_hmac_final(prng->key, sizeof(prng->key), &prng->h); + /* configure the new prng key into the prng's instance of hmac */ + (void)tc_hmac_set_key(&prng->h, prng->key, sizeof(prng->key)); + + /* use the new key to compute a new state variable v */ + (void)tc_hmac_init(&prng->h); + (void)tc_hmac_update(&prng->h, prng->v, sizeof(prng->v)); + (void)tc_hmac_final(prng->v, sizeof(prng->v), &prng->h); +} + +int tc_hmac_prng_init(TCHmacPrng_t prng, + const uint8_t *personalization, + unsigned int plen) +{ + + /* input sanity check: */ + if (prng == (TCHmacPrng_t) 0 || + personalization == (uint8_t *) 0 || + plen > MAX_PLEN) { + return TC_CRYPTO_FAIL; + } + + /* put the generator into a known state: */ + _set(prng->key, 0x00, sizeof(prng->key)); + _set(prng->v, 0x01, sizeof(prng->v)); + tc_hmac_set_key(&prng->h, prng->key, sizeof(prng->key)); + /* update assumes SOME key has been configured into HMAC */ + + update(prng, personalization, plen); + + /* force a reseed before allowing tc_hmac_prng_generate to succeed: */ + prng->countdown = 0; + + return TC_CRYPTO_SUCCESS; +} + +int tc_hmac_prng_reseed(TCHmacPrng_t prng, + const uint8_t *seed, + unsigned int seedlen, + const uint8_t *additional_input, + unsigned int additionallen) +{ + + /* input sanity check: */ + if (prng == (TCHmacPrng_t) 0 || + seed == (const uint8_t *) 0 || + seedlen < MIN_SLEN || + seedlen > MAX_SLEN) { + return TC_CRYPTO_FAIL; + } + + if (additional_input != (const uint8_t *) 0) { + /* + * Abort if additional_input is provided but has inappropriate + * length + */ + if (additionallen == 0 || + additionallen > MAX_ALEN) { + return TC_CRYPTO_FAIL; + } else { + /* call update for the seed and additional_input */ + update(prng, seed, seedlen); + update(prng, additional_input, additionallen); + } + } else { + /* call update only for the seed */ + update(prng, seed, seedlen); + } + + /* ... and enable hmac_prng_generate */ + prng->countdown = MAX_GENS; + + return TC_CRYPTO_SUCCESS; +} + +int tc_hmac_prng_generate(uint8_t *out, unsigned int outlen, TCHmacPrng_t prng) +{ + unsigned int bufferlen; + + /* input sanity check: */ + if (out == (uint8_t *) 0 || + prng == (TCHmacPrng_t) 0 || + outlen == 0 || + outlen > MAX_OUT) { + return TC_CRYPTO_FAIL; + } else if (prng->countdown == 0) { + return TC_HMAC_PRNG_RESEED_REQ; + } + + prng->countdown--; + + while (outlen != 0) { + /* operate HMAC in OFB mode to create "random" outputs */ + (void)tc_hmac_init(&prng->h); + (void)tc_hmac_update(&prng->h, prng->v, sizeof(prng->v)); + (void)tc_hmac_final(prng->v, sizeof(prng->v), &prng->h); + + bufferlen = (TC_SHA256_DIGEST_SIZE > outlen) ? + outlen : TC_SHA256_DIGEST_SIZE; + (void)_copy(out, bufferlen, prng->v, bufferlen); + + out += bufferlen; + outlen = (outlen > TC_SHA256_DIGEST_SIZE) ? + (outlen - TC_SHA256_DIGEST_SIZE) : 0; + } + + /* block future PRNG compromises from revealing past state */ + update(prng, prng->v, TC_SHA256_DIGEST_SIZE); + + return TC_CRYPTO_SUCCESS; +} |