60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/* Copyright 2015 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "internal.h"
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#include "dcrypto.h"
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#include <stdint.h>
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#include "cryptoc/sha256.h"
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#include "cryptoc/util.h"
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/* TODO(ngm): add support for hardware hmac. */
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static void HMAC_init(LITE_HMAC_CTX *ctx, const void *key, unsigned int len)
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{
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unsigned int i;
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memset(&ctx->opad[0], 0, sizeof(ctx->opad));
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if (len > sizeof(ctx->opad)) {
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DCRYPTO_SHA256_init(&ctx->hash, 0);
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HASH_update(&ctx->hash, key, len);
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memcpy(&ctx->opad[0], HASH_final(&ctx->hash),
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HASH_size(&ctx->hash));
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} else {
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memcpy(&ctx->opad[0], key, len);
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}
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for (i = 0; i < sizeof(ctx->opad); ++i)
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ctx->opad[i] ^= 0x36;
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DCRYPTO_SHA256_init(&ctx->hash, 0);
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/* hash ipad */
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HASH_update(&ctx->hash, ctx->opad, sizeof(ctx->opad));
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for (i = 0; i < sizeof(ctx->opad); ++i)
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ctx->opad[i] ^= (0x36 ^ 0x5c);
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}
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void DCRYPTO_HMAC_SHA256_init(LITE_HMAC_CTX *ctx, const void *key,
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unsigned int len)
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{
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HMAC_init(ctx, key, len);
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}
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const uint8_t *DCRYPTO_HMAC_final(LITE_HMAC_CTX *ctx)
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{
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uint8_t digest[SHA_DIGEST_MAX_BYTES]; /* upto SHA2 */
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memcpy(digest, HASH_final(&ctx->hash),
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(HASH_size(&ctx->hash) <= sizeof(digest) ?
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HASH_size(&ctx->hash) : sizeof(digest)));
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DCRYPTO_SHA256_init(&ctx->hash, 0);
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HASH_update(&ctx->hash, ctx->opad, sizeof(ctx->opad));
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HASH_update(&ctx->hash, digest, HASH_size(&ctx->hash));
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always_memset(&ctx->opad[0], 0, sizeof(ctx->opad)); /* wipe key */
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return HASH_final(&ctx->hash);
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}
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