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/*
Unix SMB/CIFS implementation.
Interface header: HMAC SHA-256 code
Copyright (C) Andrew Tridgell 2008
based in hmacsha1.c which is:
Copyright (C) Stefan Metzmacher
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
taken direct from rfc2202 implementation and modified for suitable use
*/
#include "includes.h"
#include "lib/crypto/crypto.h"
/***********************************************************************
the rfc 2104/2202 version of hmac_sha256 initialisation.
***********************************************************************/
_PUBLIC_ void hmac_sha256_init(const uint8_t *key, size_t key_len, struct HMACSHA256Context *ctx)
{
int i;
uint8_t tk[SHA256_DIGEST_LENGTH];
/* if key is longer than 64 bytes reset it to key=HASH(key) */
if (key_len > 64)
{
SHA256_CTX tctx;
SHA256_Init(&tctx);
SHA256_Update(&tctx, key, key_len);
SHA256_Final(tk, &tctx);
key = tk;
key_len = SHA256_DIGEST_LENGTH;
}
/* start out by storing key in pads */
ZERO_STRUCT(ctx->k_ipad);
ZERO_STRUCT(ctx->k_opad);
memcpy( ctx->k_ipad, key, key_len);
memcpy( ctx->k_opad, key, key_len);
/* XOR key with ipad and opad values */
for (i=0; i<64; i++)
{
ctx->k_ipad[i] ^= 0x36;
ctx->k_opad[i] ^= 0x5c;
}
SHA256_Init(&ctx->ctx);
SHA256_Update(&ctx->ctx, ctx->k_ipad, 64);
}
/***********************************************************************
update hmac_sha256 "inner" buffer
***********************************************************************/
_PUBLIC_ void hmac_sha256_update(const uint8_t *data, size_t data_len, struct HMACSHA256Context *ctx)
{
SHA256_Update(&ctx->ctx, data, data_len); /* then text of datagram */
}
/***********************************************************************
finish off hmac_sha256 "inner" buffer and generate outer one.
***********************************************************************/
_PUBLIC_ void hmac_sha256_final(uint8_t digest[SHA256_DIGEST_LENGTH], struct HMACSHA256Context *ctx)
{
SHA256_CTX ctx_o;
SHA256_Final(digest, &ctx->ctx);
SHA256_Init(&ctx_o);
SHA256_Update(&ctx_o, ctx->k_opad, 64);
SHA256_Update(&ctx_o, digest, SHA256_DIGEST_LENGTH);
SHA256_Final(digest, &ctx_o);
}
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