110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
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/*
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* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <string.h>
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#include "internal.h"
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static uint8_t zeros[HMAC_HASHLEN_MAX];
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static int
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hkdf_kdf(uint8_t *out, size_t *outlen, void *initparams, size_t len)
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{
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struct lc_hkdf_params *params = initparams;
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struct lc_hmac_params hmacparams;
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uint8_t prk[HMAC_HASHLEN_MAX];
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uint8_t t[HMAC_HASHLEN_MAX], tn[HMAC_HASHLEN_MAX];
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size_t hashlen, olen;
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uint8_t ctr;
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/* Only accept HMAC as auth_impl. */
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if (params->hmac == NULL ||
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params->hmac->impl != lc_auth_impl_hmac())
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return 0;
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hashlen = params->hash->impl->hashlen;
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/* XXX *outlen = 0 ? */
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if (len > hashlen * 255)
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return 0;
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if (out == NULL) {
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*outlen = len;
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return 1;
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}
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*outlen = 0;
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hmacparams.hash = params->hash;
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if (params->saltlen == 0) {
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hmacparams.key = zeros;
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hmacparams.keylen = hashlen;
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} else {
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hmacparams.key = params->salt;
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hmacparams.keylen = params->saltlen;
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}
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if (!lc_auth(params->hmac->impl, prk, &olen, &hmacparams, params->ikm,
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params->ikmlen))
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return 0;
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hmacparams.key = prk;
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hmacparams.keylen = olen;
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olen = 0;
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ctr = 1;
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while (len >= hashlen) {
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memcpy(t, tn, olen);
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if (!lc_auth_init(params->hmac, &hmacparams) ||
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!lc_auth_update(params->hmac, t, olen) ||
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!lc_auth_update(params->hmac, params->info,
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params->infolen) ||
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!lc_auth_update(params->hmac, &ctr, sizeof(ctr)) ||
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!lc_auth_final(params->hmac, tn, &olen))
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return 0;
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ctr++;
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memcpy(out, tn, hashlen);
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*outlen += hashlen;
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out += hashlen;
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len -= hashlen;
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}
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memcpy(t, tn, olen);
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if (!lc_auth_init(params->hmac, &hmacparams) ||
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!lc_auth_update(params->hmac, t, olen) ||
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!lc_auth_update(params->hmac, params->info, params->infolen) ||
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!lc_auth_update(params->hmac, &ctr, sizeof(ctr)) ||
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!lc_auth_final(params->hmac, tn, &olen))
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return 0;
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memcpy(out, tn, len);
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*outlen += len;
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return 1;
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}
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const struct lc_kdf_impl *
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lc_kdf_impl_hkdf(void)
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{
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static struct lc_kdf_impl hkdf_impl = {
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.kdf = &hkdf_kdf,
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};
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return &hkdf_impl;
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}
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