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/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
static inline size_t
block_size(const br_hash_class *dig)
{
unsigned ls;
ls = (unsigned)(dig->desc >> BR_HASHDESC_LBLEN_OFF)
& BR_HASHDESC_LBLEN_MASK;
return (size_t)1 << ls;
}
static void
process_key(const br_hash_class **hc, void *ks,
const void *key, size_t key_len, unsigned bb)
{
unsigned char tmp[256];
size_t blen, u;
blen = block_size(*hc);
memcpy(tmp, key, key_len);
for (u = 0; u < key_len; u ++) {
tmp[u] ^= (unsigned char)bb;
}
memset(tmp + key_len, bb, blen - key_len);
(*hc)->init(hc);
(*hc)->update(hc, tmp, blen);
(*hc)->state(hc, ks);
}
/* see bearssl.h */
void
br_hmac_key_init(br_hmac_key_context *kc,
const br_hash_class *dig, const void *key, size_t key_len)
{
br_hash_compat_context hc;
unsigned char kbuf[64];
kc->dig_vtable = dig;
hc.vtable = dig;
if (key_len > block_size(dig)) {
dig->init(&hc.vtable);
dig->update(&hc.vtable, key, key_len);
dig->out(&hc.vtable, kbuf);
key = kbuf;
key_len = br_digest_size(dig);
}
process_key(&hc.vtable, kc->ksi, key, key_len, 0x36);
process_key(&hc.vtable, kc->kso, key, key_len, 0x5C);
}
/* see bearssl.h */
void
br_hmac_init(br_hmac_context *ctx,
const br_hmac_key_context *kc, size_t out_len)
{
const br_hash_class *dig;
size_t blen, hlen;
dig = kc->dig_vtable;
blen = block_size(dig);
dig->init(&ctx->dig.vtable);
dig->set_state(&ctx->dig.vtable, kc->ksi, (uint64_t)blen);
memcpy(ctx->kso, kc->kso, sizeof kc->kso);
hlen = br_digest_size(dig);
if (out_len > 0 && out_len < hlen) {
hlen = out_len;
}
ctx->out_len = hlen;
}
/* see bearssl.h */
void
br_hmac_update(br_hmac_context *ctx, const void *data, size_t len)
{
ctx->dig.vtable->update(&ctx->dig.vtable, data, len);
KILL_TAIL_CALL();
}
/* see bearssl.h */
size_t
br_hmac_out(const br_hmac_context *ctx, void *out)
{
const br_hash_class *dig;
br_hash_compat_context hc;
unsigned char tmp[64];
size_t blen, hlen;
dig = ctx->dig.vtable;
dig->out(&ctx->dig.vtable, tmp);
blen = block_size(dig);
dig->init(&hc.vtable);
dig->set_state(&hc.vtable, ctx->kso, (uint64_t)blen);
hlen = br_digest_size(dig);
dig->update(&hc.vtable, tmp, hlen);
dig->out(&hc.vtable, tmp);
memcpy(out, tmp, ctx->out_len);
return ctx->out_len;
}
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