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https://github.com/sheumann/65816-crypto.git
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191a27af86
This is implemented in the common HMAC code and can apply to the other hash algorithms as well, but the header and tests are currently only implemented for HMAC-MD5.
115 lines
3.9 KiB
C
115 lines
3.9 KiB
C
/*
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* Copyright (c) 2023 Stephen Heumann
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* This file is a template for computing HMACs using the hash functions
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* from lib65816hash. It is #included from the files implementing the
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* hash functions, with HASH_ALG defined to the name of the hash function.
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*/
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#define join(a,b) a##b
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#define concat(a,b) join(a,b)
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#define join3(a,b,c) a##b##c
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#define concat3(a,b,c) join3(a,b,c)
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#define hash_init concat(HASH_ALG,_init)
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#define hash_update concat(HASH_ALG,_update)
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#define hash_finalize concat(HASH_ALG,_finalize)
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#define hmac_init concat3(hmac_,HASH_ALG,_init)
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#define hmac_update concat3(hmac_,HASH_ALG,_update)
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#define hmac_finalize concat3(hmac_,HASH_ALG,_finalize)
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#define hmac_compute concat3(hmac_,HASH_ALG,_compute)
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#define hmac_context concat3(hmac_,HASH_ALG,_context)
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#define BLOCK_SIZE sizeof(context->u[0].ctx.block)
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#define HASH_SIZE sizeof(context->u[0].ctx.hash)
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void hmac_init(struct hmac_context *context,
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const unsigned char *key,
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unsigned long key_length)
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{
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unsigned i;
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// Compute adjusted key (hashed from original key if necessary)
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memset(context->u[0].k, 0, BLOCK_SIZE);
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if (key_length <= BLOCK_SIZE) {
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memcpy(context->u[0].k, key, key_length);
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} else {
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hash_init(&context->u[1].ctx);
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hash_update(&context->u[1].ctx, key, key_length);
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hash_finalize(&context->u[1].ctx);
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memcpy(context->u[0].k, context->u[1].ctx.hash, HASH_SIZE);
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}
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// Set context->u[0].k to K XOR opad, context->u[1].k to K XOR ipad
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for (i = 0; i < BLOCK_SIZE; i++) {
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context->u[1].k[i] = context->u[0].k[i] ^ 0x36;
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context->u[0].k[i] ^= 0x5C;
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}
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// Save inner hash context following initial block as context->u[2].ctx
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hash_init(&context->u[2].ctx);
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hash_update(&context->u[2].ctx, context->u[1].k, BLOCK_SIZE);
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// Save outer hash context following initial block as context->u[1].ctx
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hash_init(&context->u[1].ctx);
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hash_update(&context->u[1].ctx, context->u[0].k, BLOCK_SIZE);
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// initialize context for use with hmac_update
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context->u[0].ctx = context->u[2].ctx;
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}
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void hmac_update(struct hmac_context *context,
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const unsigned char *message_part,
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unsigned long part_length)
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{
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hash_update(&context->u[0].ctx, message_part, part_length);
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}
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void hmac_finalize(struct hmac_context *context)
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{
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// finalize inner hash
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hash_finalize(&context->u[0].ctx);
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memcpy(context->inner_hash, context->u[0].ctx.hash, HASH_SIZE);
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// Compute outer hash
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context->u[0].ctx = context->u[1].ctx;
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hash_update(&context->u[0].ctx, context->inner_hash, HASH_SIZE);
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hash_finalize(&context->u[0].ctx);
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}
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void hmac_compute(struct hmac_context *context,
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const unsigned char *message,
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unsigned long message_length)
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{
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// Compute inner hash
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context->u[0].ctx = context->u[2].ctx;
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hash_update(&context->u[0].ctx, message, message_length);
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hash_finalize(&context->u[0].ctx);
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memcpy(context->inner_hash, context->u[0].ctx.hash, HASH_SIZE);
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// Compute outer hash
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context->u[0].ctx = context->u[1].ctx;
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hash_update(&context->u[0].ctx, context->inner_hash, HASH_SIZE);
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hash_finalize(&context->u[0].ctx);
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}
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