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88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
/* hmac.c -- hashed message authentication codes
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Copyright (C) 2005-2006, 2009-2026 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <string.h>
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#include "memxor.h"
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#define IPAD 0x36
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#define OPAD 0x5c
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/* Concatenate two preprocessor tokens. */
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#define _GLHMAC_CONCAT_(prefix, suffix) prefix##suffix
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#define _GLHMAC_CONCAT(prefix, suffix) _GLHMAC_CONCAT_ (prefix, suffix)
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#if GL_HMAC_NAME == 5
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# define HMAC_ALG md5
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#else
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# define HMAC_ALG _GLHMAC_CONCAT (sha, GL_HMAC_NAME)
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#endif
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#define GL_HMAC_CTX _GLHMAC_CONCAT (HMAC_ALG, _ctx)
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#define GL_HMAC_FN _GLHMAC_CONCAT (hmac_, HMAC_ALG)
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#define GL_HMAC_FN_INIT _GLHMAC_CONCAT (HMAC_ALG, _init_ctx)
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#define GL_HMAC_FN_BLOC _GLHMAC_CONCAT (HMAC_ALG, _process_block)
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#define GL_HMAC_FN_PROC _GLHMAC_CONCAT (HMAC_ALG, _process_bytes)
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#define GL_HMAC_FN_FINI _GLHMAC_CONCAT (HMAC_ALG, _finish_ctx)
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static void
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hmac_hash (const void *key, size_t keylen,
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const void *in, size_t inlen,
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int pad, void *resbuf)
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{
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char block[GL_HMAC_BLOCKSIZE];
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memset (block, pad, sizeof block);
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memxor (block, key, keylen);
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struct GL_HMAC_CTX hmac_ctx;
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GL_HMAC_FN_INIT (&hmac_ctx);
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GL_HMAC_FN_BLOC (block, sizeof block, &hmac_ctx);
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GL_HMAC_FN_PROC (in, inlen, &hmac_ctx);
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GL_HMAC_FN_FINI (&hmac_ctx, resbuf);
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}
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int
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GL_HMAC_FN (const void *key, size_t keylen,
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const void *in, size_t inlen, void *resbuf)
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{
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char optkeybuf[GL_HMAC_HASHSIZE];
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/* Ensure key size is <= block size. */
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if (keylen > GL_HMAC_BLOCKSIZE)
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{
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struct GL_HMAC_CTX keyhash;
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GL_HMAC_FN_INIT (&keyhash);
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GL_HMAC_FN_PROC (key, keylen, &keyhash);
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GL_HMAC_FN_FINI (&keyhash, optkeybuf);
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key = optkeybuf;
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/* zero padding of the key to the block size
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is implicit in the memxor. */
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keylen = sizeof optkeybuf;
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}
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/* Compute INNERHASH from KEY and IN. */
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char innerhash[GL_HMAC_HASHSIZE];
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hmac_hash (key, keylen, in, inlen, IPAD, innerhash);
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/* Compute result from KEY and INNERHASH. */
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hmac_hash (key, keylen, innerhash, sizeof innerhash, OPAD, resbuf);
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return 0;
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}
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