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/* hmac.c -- hashed message authentication codes
Copyright (C) 2005-2006, 2009-2020 Free Software Foundation, Inc.
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 2, 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 <https://www.gnu.org/licenses/>. */
#include <string.h>
#include "memxor.h"
#define IPAD 0x36
#define OPAD 0x5c
/* Concatenate two preprocessor tokens. */
#define _GLHMAC_CONCAT_(prefix, suffix) prefix##suffix
#define _GLHMAC_CONCAT(prefix, suffix) _GLHMAC_CONCAT_ (prefix, suffix)
#if GL_HMAC_NAME == 5
# define HMAC_ALG md5
#else
# define HMAC_ALG _GLHMAC_CONCAT (sha, GL_HMAC_NAME)
#endif
#define GL_HMAC_CTX _GLHMAC_CONCAT (HMAC_ALG, _ctx)
#define GL_HMAC_FN _GLHMAC_CONCAT (hmac_, HMAC_ALG)
#define GL_HMAC_FN_INIT _GLHMAC_CONCAT (HMAC_ALG, _init_ctx)
#define GL_HMAC_FN_BLOC _GLHMAC_CONCAT (HMAC_ALG, _process_block)
#define GL_HMAC_FN_PROC _GLHMAC_CONCAT (HMAC_ALG, _process_bytes)
#define GL_HMAC_FN_FINI _GLHMAC_CONCAT (HMAC_ALG, _finish_ctx)
static void
hmac_hash (const void *key, size_t keylen,
const void *in, size_t inlen,
int pad, void *resbuf)
{
struct GL_HMAC_CTX hmac_ctx;
char block[GL_HMAC_BLOCKSIZE];
memset (block, pad, sizeof block);
memxor (block, key, keylen);
GL_HMAC_FN_INIT (&hmac_ctx);
GL_HMAC_FN_BLOC (block, sizeof block, &hmac_ctx);
GL_HMAC_FN_PROC (in, inlen, &hmac_ctx);
GL_HMAC_FN_FINI (&hmac_ctx, resbuf);
}
int
GL_HMAC_FN (const void *key, size_t keylen,
const void *in, size_t inlen, void *resbuf)
{
char optkeybuf[GL_HMAC_HASHSIZE];
char innerhash[GL_HMAC_HASHSIZE];
/* Ensure key size is <= block size. */
if (keylen > GL_HMAC_BLOCKSIZE)
{
struct GL_HMAC_CTX keyhash;
GL_HMAC_FN_INIT (&keyhash);
GL_HMAC_FN_PROC (key, keylen, &keyhash);
GL_HMAC_FN_FINI (&keyhash, optkeybuf);
key = optkeybuf;
/* zero padding of the key to the block size
is implicit in the memxor. */
keylen = sizeof optkeybuf;
}
/* Compute INNERHASH from KEY and IN. */
hmac_hash (key, keylen, in, inlen, IPAD, innerhash);
/* Compute result from KEY and INNERHASH. */
hmac_hash (key, keylen, innerhash, sizeof innerhash, OPAD, resbuf);
return 0;
}
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