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285 lines
8.7 KiB
C
285 lines
8.7 KiB
C
/*-
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* Copyright 2005 Colin Percival
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* Copyright 2013 Christian Mehlis & René Kijewski
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* Copyright 2016 Martin Landsmann <martin.landsmann@haw-hamburg.de>
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* Copyright 2016 OTA keys S.A.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD: src/lib/libmd/sha256c.c,v 1.2 2006/01/17 15:35:56 phk Exp $
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*/
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/**
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* @ingroup sys_hashes
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* @{
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*
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* @file
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* @brief SHA256 hash function implementation
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*
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* @author Colin Percival
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* @author Christian Mehlis
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* @author Rene Kijewski
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* @author Martin Landsmann
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* @author Hermann Lelong
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*
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* @}
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*/
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#include <string.h>
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#include <assert.h>
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#include "hashes/sha256.h"
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#include "hashes/sha2xx_common.h"
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/* SHA-256 initialization. Begins a SHA-256 operation. */
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void sha256_init(sha256_context_t *ctx)
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{
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/* Zero bits processed so far */
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ctx->count[0] = ctx->count[1] = 0;
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/* Magic initialization constants */
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ctx->state[0] = 0x6A09E667;
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ctx->state[1] = 0xBB67AE85;
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ctx->state[2] = 0x3C6EF372;
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ctx->state[3] = 0xA54FF53A;
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ctx->state[4] = 0x510E527F;
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ctx->state[5] = 0x9B05688C;
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ctx->state[6] = 0x1F83D9AB;
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ctx->state[7] = 0x5BE0CD19;
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}
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void sha256(const void *data, size_t len, void *digest)
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{
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sha256_context_t c;
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assert(digest);
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sha256_init(&c);
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sha256_update(&c, data, len);
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sha256_final(&c, digest);
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}
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void hmac_sha256_init(hmac_context_t *ctx, const void *key, size_t key_length)
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{
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unsigned char k[SHA256_INTERNAL_BLOCK_SIZE];
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memset((void *)k, 0x00, SHA256_INTERNAL_BLOCK_SIZE);
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if (key_length > SHA256_INTERNAL_BLOCK_SIZE) {
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sha256(key, key_length, k);
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}
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else {
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memcpy((void *)k, key, key_length);
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}
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/*
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* create the inner and outer keypads
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* rising hamming distance enforcing i_* and o_* are distinct
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* in at least one bit
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*/
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unsigned char o_key_pad[SHA256_INTERNAL_BLOCK_SIZE];
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unsigned char i_key_pad[SHA256_INTERNAL_BLOCK_SIZE];
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for (size_t i = 0; i < SHA256_INTERNAL_BLOCK_SIZE; ++i) {
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o_key_pad[i] = 0x5c ^ k[i];
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i_key_pad[i] = 0x36 ^ k[i];
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}
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/*
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* Initiate calculation of the inner hash
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* tmp = hash(i_key_pad CONCAT message)
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*/
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sha256_init(&ctx->c_in);
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sha2xx_update(&ctx->c_in, i_key_pad, SHA256_INTERNAL_BLOCK_SIZE);
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/*
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* Initiate calculation of the outer hash
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* result = hash(o_key_pad CONCAT tmp)
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*/
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sha256_init(&ctx->c_out);
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sha2xx_update(&ctx->c_out, o_key_pad, SHA256_INTERNAL_BLOCK_SIZE);
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}
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void hmac_sha256_update(hmac_context_t *ctx, const void *data, size_t len)
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{
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sha2xx_update(&ctx->c_in, data, len);
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}
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void hmac_sha256_final(hmac_context_t *ctx, void *digest)
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{
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unsigned char tmp[SHA256_DIGEST_LENGTH];
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sha256_final(&ctx->c_in, tmp);
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sha2xx_update(&ctx->c_out, tmp, SHA256_DIGEST_LENGTH);
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sha256_final(&ctx->c_out, digest);
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}
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void hmac_sha256(const void *key, size_t key_length,
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const void *data, size_t len, void *digest)
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{
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hmac_context_t ctx;
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hmac_sha256_init(&ctx, key, key_length);
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hmac_sha256_update(&ctx,data, len);
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hmac_sha256_final(&ctx, digest);
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}
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/**
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* @brief helper to compute sha256 inplace for the given buffer
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*
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* @param[in, out] element the buffer to compute a sha256 and store it back to it
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*
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*/
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static inline void sha256_inplace(unsigned char element[SHA256_DIGEST_LENGTH])
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{
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sha256_context_t ctx;
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sha256_init(&ctx);
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sha2xx_update(&ctx, element, SHA256_DIGEST_LENGTH);
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sha256_final(&ctx, element);
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}
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void *sha256_chain(const void *seed, size_t seed_length,
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size_t elements, void *tail_element)
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{
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unsigned char tmp_element[SHA256_DIGEST_LENGTH];
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/* assert if no sha256-chain can be created */
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assert(elements >= 2);
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/* 1st iteration */
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sha256(seed, seed_length, tmp_element);
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/* perform consecutive iterations minus the first one */
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for (size_t i = 0; i < (elements - 1); ++i) {
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sha256_inplace(tmp_element);
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}
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/* store the result */
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memcpy(tail_element, tmp_element, SHA256_DIGEST_LENGTH);
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return tail_element;
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}
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void *sha256_chain_with_waypoints(const void *seed,
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size_t seed_length,
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size_t elements,
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void *tail_element,
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sha256_chain_idx_elm_t *waypoints,
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size_t *waypoints_length)
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{
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/* assert if no sha256-chain can be created */
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assert(elements >= 2);
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/* assert to prevent division by 0 */
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assert(*waypoints_length > 0);
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/* assert if no waypoints can be created */
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assert(*waypoints_length > 1);
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/* if we have enough space we store the whole chain */
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if (*waypoints_length >= elements) {
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/* 1st iteration */
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sha256(seed, seed_length, waypoints[0].element);
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waypoints[0].index = 0;
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/* perform consecutive iterations starting at index 1*/
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for (size_t i = 1; i < elements; ++i) {
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sha256_context_t ctx;
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sha256_init(&ctx);
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sha2xx_update(&ctx, waypoints[(i - 1)].element, SHA256_DIGEST_LENGTH);
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sha256_final(&ctx, waypoints[i].element);
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waypoints[i].index = i;
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}
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/* store the result */
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memcpy(tail_element, waypoints[(elements - 1)].element, SHA256_DIGEST_LENGTH);
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*waypoints_length = (elements - 1);
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return tail_element;
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}
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else {
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unsigned char tmp_element[SHA256_DIGEST_LENGTH];
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size_t waypoint_streak = (elements / *waypoints_length);
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/* 1st waypoint iteration */
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sha256(seed, seed_length, tmp_element);
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for (size_t i = 1; i < waypoint_streak; ++i) {
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sha256_inplace(tmp_element);
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}
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memcpy(waypoints[0].element, tmp_element, SHA256_DIGEST_LENGTH);
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waypoints[0].index = (waypoint_streak - 1);
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/* index of the current computed element in the chain */
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size_t index = (waypoint_streak - 1);
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/* consecutive waypoint iterations */
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size_t j = 1;
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for (; j < *waypoints_length; ++j) {
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for (size_t i = 0; i < waypoint_streak; ++i) {
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sha256_inplace(tmp_element);
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index++;
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}
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memcpy(waypoints[j].element, tmp_element, SHA256_DIGEST_LENGTH);
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waypoints[j].index = index;
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}
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/* store/pass the last used index in the waypoint array */
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*waypoints_length = (j - 1);
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/* remaining iterations down to elements */
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for (size_t i = index; i < (elements - 1); ++i) {
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sha256_inplace(tmp_element);
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}
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/* store the result */
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memcpy(tail_element, tmp_element, SHA256_DIGEST_LENGTH);
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return tail_element;
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}
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}
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int sha256_chain_verify_element(void *element,
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size_t element_index,
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void *tail_element,
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size_t chain_length)
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{
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unsigned char tmp_element[SHA256_DIGEST_LENGTH];
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int delta_count = (chain_length - element_index);
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/* assert if we have an index mismatch */
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assert(delta_count >= 1);
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memcpy((void *)tmp_element, element, SHA256_DIGEST_LENGTH);
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/* perform all consecutive iterations down to tail_element */
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for (int i = 0; i < (delta_count - 1); ++i) {
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sha256_inplace(tmp_element);
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}
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/* return if the computed element equals the tail_element */
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return (memcmp(tmp_element, tail_element, SHA256_DIGEST_LENGTH) != 0);
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}
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