146 lines
5.0 KiB
C
146 lines
5.0 KiB
C
/*
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---------------------------------------------------------------------------
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Copyright (c) 2002, Dr Brian Gladman, Worcester, UK. All rights reserved.
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LICENSE TERMS
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The free distribution and use of this software in both source and binary
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form is allowed (with or without changes) provided that:
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1. distributions of this source code include the above copyright
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notice, this list of conditions and the following disclaimer;
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2. distributions in binary form include the above copyright
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notice, this list of conditions and the following disclaimer
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in the documentation and/or other associated materials;
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3. the copyright holder's name is not used to endorse products
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built using this software without specific written permission.
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ALTERNATIVELY, provided that this notice is retained in full, this product
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may be distributed under the terms of the GNU General Public License (GPL),
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in which case the provisions of the GPL apply INSTEAD OF those given above.
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DISCLAIMER
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This software is provided 'as is' with no explicit or implied warranties
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in respect of its properties, including, but not limited to, correctness
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and/or fitness for purpose.
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---------------------------------------------------------------------------
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Issue Date: 26/08/2003
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This is an implementation of HMAC, the FIPS standard keyed hash function
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*/
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#define _ISOC99_SOURCE
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#include "hmac.h"
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#if defined(__cplusplus)
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extern "C"
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{
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#endif
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/* initialise the HMAC context to zero */
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void hmac_sha_begin(hmac_ctx cx[1])
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{
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memset(cx, 0, sizeof(hmac_ctx));
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}
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/* input the HMAC key (can be called multiple times) */
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int hmac_sha_key(const unsigned char key[], unsigned long key_len, hmac_ctx cx[1])
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{
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if(cx->klen == HMAC_IN_DATA) /* error if further key input */
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return HMAC_BAD_MODE; /* is attempted in data mode */
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if(cx->klen + key_len > HASH_INPUT_SIZE) /* if the key has to be hashed */
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{
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if(cx->klen <= HASH_INPUT_SIZE) /* if the hash has not yet been */
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{ /* started, initialise it and */
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sha_begin(cx->ctx); /* hash stored key characters */
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sha_hash(cx->key, cx->klen, cx->ctx);
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}
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sha_hash(key, key_len, cx->ctx); /* hash long key data into hash */
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}
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else /* otherwise store key data */
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memcpy(cx->key + cx->klen, key, key_len);
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cx->klen += key_len; /* update the key length count */
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return HMAC_OK;
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}
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/* input the HMAC data (can be called multiple times) - */
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/* note that this call terminates the key input phase */
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void hmac_sha_data(const unsigned char data[], unsigned long data_len, hmac_ctx cx[1])
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{ unsigned int i;
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if(cx->klen != HMAC_IN_DATA) /* if not yet in data phase */
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{
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if(cx->klen > HASH_INPUT_SIZE) /* if key is being hashed */
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{ /* complete the hash and */
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sha_end(cx->key, cx->ctx); /* store the result as the */
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cx->klen = HASH_OUTPUT_SIZE; /* key and set new length */
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}
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/* pad the key if necessary */
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memset(cx->key + cx->klen, 0, HASH_INPUT_SIZE - cx->klen);
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/* xor ipad into key value */
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for(i = 0; i < (HASH_INPUT_SIZE >> 2); ++i)
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((uint_32t*)cx->key)[i] ^= 0x36363636;
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/* and start hash operation */
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sha_begin(cx->ctx);
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sha_hash(cx->key, HASH_INPUT_SIZE, cx->ctx);
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/* mark as now in data mode */
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cx->klen = HMAC_IN_DATA;
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}
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/* hash the data (if any) */
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if(data_len)
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sha_hash(data, data_len, cx->ctx);
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}
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/* compute and output the MAC value */
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void hmac_sha_end(unsigned char mac[], unsigned long mac_len, hmac_ctx cx[1])
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{ unsigned char dig[HASH_OUTPUT_SIZE];
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unsigned int i;
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/* if no data has been entered perform a null data phase */
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if(cx->klen != HMAC_IN_DATA)
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hmac_sha_data((const unsigned char*)0, 0, cx);
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sha_end(dig, cx->ctx); /* complete the inner hash */
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/* set outer key value using opad and removing ipad */
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for(i = 0; i < (HASH_INPUT_SIZE >> 2); ++i)
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((uint_32t*)cx->key)[i] ^= 0x36363636 ^ 0x5c5c5c5c;
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/* perform the outer hash operation */
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sha_begin(cx->ctx);
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sha_hash(cx->key, HASH_INPUT_SIZE, cx->ctx);
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sha_hash(dig, HASH_OUTPUT_SIZE, cx->ctx);
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sha_end(dig, cx->ctx);
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/* output the hash value */
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for(i = 0; i < mac_len; ++i)
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mac[i] = dig[i];
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}
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/* 'do it all in one go' subroutine */
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void hmac_sha(const unsigned char key[], unsigned long key_len,
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const unsigned char data[], unsigned long data_len,
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unsigned char mac[], unsigned long mac_len)
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{ hmac_ctx cx[1];
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hmac_sha_begin(cx);
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hmac_sha_key(key, key_len, cx);
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hmac_sha_data(data, data_len, cx);
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hmac_sha_end(mac, mac_len, cx);
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}
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#if defined(__cplusplus)
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}
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#endif
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