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/* Copyright 2016 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "2hmac.h"
#include "2sha.h"
#include "2sysincludes.h"
int hmac(enum vb2_hash_algorithm alg,
const void *key, uint32_t key_size,
const void *msg, uint32_t msg_size,
uint8_t *mac, uint32_t mac_size)
{
uint32_t block_size;
uint32_t digest_size;
uint8_t k[VB2_MAX_BLOCK_SIZE];
uint8_t o_pad[VB2_MAX_BLOCK_SIZE];
uint8_t i_pad[VB2_MAX_BLOCK_SIZE];
uint8_t b[VB2_MAX_DIGEST_SIZE];
struct vb2_digest_context dc;
int i;
if (!key | !msg | !mac)
return -1;
digest_size = vb2_digest_size(alg);
block_size = vb2_hash_block_size(alg);
if (!digest_size || !block_size)
return -1;
if (mac_size < digest_size)
return -1;
if (key_size > block_size) {
vb2_digest_buffer((uint8_t *)key, key_size, alg, k, block_size);
key_size = digest_size;
} else {
memcpy(k, key, key_size);
}
if (key_size < block_size)
memset(k + key_size, 0, block_size - key_size);
for (i = 0; i < block_size; i++) {
o_pad[i] = 0x5c ^ k[i];
i_pad[i] = 0x36 ^ k[i];
}
vb2_digest_init(&dc, alg);
vb2_digest_extend(&dc, i_pad, block_size);
vb2_digest_extend(&dc, msg, msg_size);
vb2_digest_finalize(&dc, b, digest_size);
vb2_digest_init(&dc, alg);
vb2_digest_extend(&dc, o_pad, block_size);
vb2_digest_extend(&dc, b, digest_size);
vb2_digest_finalize(&dc, mac, mac_size);
return 0;
}
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