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avr-crypto-lib/sha256/sha256.c

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/* sha256.c */
/*
This file is part of the AVR-Crypto-Lib.
Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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 3 of the License, 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 <http://www.gnu.org/licenses/>.
*/
/**
* \file sha256.c
* \author Daniel Otte
* \date 16.05.2006
*
* \par License:
* GPL
*
* \brief SHA-256 implementation.
*
*
*/
#include <stdint.h>
#include <string.h> /* for memcpy, memmove, memset */
#include <avr/pgmspace.h>
#include "sha256.h"
#define LITTLE_ENDIAN
#if defined LITTLE_ENDIAN
#elif defined BIG_ENDIAN
#else
#error specify endianess!!!
#endif
/*************************************************************************/
static const uint32_t sha256_init_vector[] PROGMEM = {
0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL,
0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL };
/*************************************************************************/
/**
* \brief \c sh256_init initialises a sha256 context for hashing.
* \c sh256_init c initialises the given sha256 context for hashing
* @param state pointer to a sha256 context
* @return none
*/
void sha256_init(sha256_ctx_t *state){
state->length = 0;
memcpy_P(state->h, sha256_init_vector, 8 * 4);
}
/*************************************************************************/
/**
* rotate x right by n positions
*/
uint32_t rotr32( uint32_t x, uint8_t n){
return ((x >> n) | (x << (32 - n)));
}
/*************************************************************************/
// #define CHANGE_ENDIAN32(x) (((x)<<24) | ((x)>>24) | (((x)& 0x0000ff00)<<8) | (((x)& 0x00ff0000)>>8))
uint32_t change_endian32(uint32_t x){
return ( ((x) << 24)
| ((x) >> 24)
| (((x) & 0x0000ff00UL) << 8)
| (((x) & 0x00ff0000UL) >> 8) );
}
/*************************************************************************/
/* sha256 functions as macros for speed and size, cause they are called only once */
#define CH(x,y,z) (((x) & (y)) ^ ((~(x)) & (z)))
#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define SIGMA0(x) (rotr32((x), 2) ^ rotr32((x), 13) ^ rotr32((x), 22))
#define SIGMA1(x) (rotr32((x), 6) ^ rotr32((x), 11) ^ rotr32((x), 25))
#define SIGMA_a(x) (rotr32((x), 7) ^ rotr32((x), 18) ^ ((x) >> 3))
#define SIGMA_b(x) (rotr32((x), 17) ^ rotr32((x), 19) ^ ((x) >> 10))
static const uint32_t k[] PROGMEM = {
0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL, 0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL, 0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL, 0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL, 0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL, 0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL, 0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL, 0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL, 0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
};
/*************************************************************************/
/**
* block must be 512 Bit = 64 Byte long !!!
*/
void sha256_nextBlock (sha256_ctx_t *state, const void *block){
uint32_t w[16]; /* this is 64 Byte large, */
uint8_t i;
uint32_t a[8], t1, t2;
/* init working variables */
memcpy((void*)a,(void*)(state->h), 8 * 4);
/* init w */
#if defined LITTLE_ENDIAN
for (i = 0; i < 16; ++i) {
w[i] = change_endian32(((uint32_t*)block)[i]);
}
#elif defined BIG_ENDIAN
memcpy((void*)w, block, 64);
#endif
/*
for (i = 16; i < 64; ++i) {
w[i] = SIGMA_b(w[i - 2]) + w[i - 7] + SIGMA_a(w[i - 15]) + w[i - 16];
}
*/
/* do the, fun stuff, */
for (i=0; i<64; ++i) {
if (i > 15) {
w[i % 16] = SIGMA_b(w[(i + 14) % 16])
+ w[(i + 9) % 16]
+ SIGMA_a(w[(i + 1) % 16])
+ w[i % 16];
}
t1 = a[7] + SIGMA1(a[4]) + CH(a[4], a[5], a[6]) + pgm_read_dword(&k[i]) + w[i % 16];
t2 = SIGMA0(a[0]) + MAJ(a[0], a[1], a[2]);
memmove(&(a[1]), &(a[0]), 7 * 4); /* a[7]=a[6]; a[6]=a[5]; a[5]=a[4]; a[4]=a[3]; a[3]=a[2]; a[2]=a[1]; a[1]=a[0]; */
a[4] += t1;
a[0] = t1 + t2;
}
/* update, the, state, */
for (i = 0; i < 8; ++i){
state->h[i] += a[i];
}
state->length += 1;
}
/*************************************************************************/
/**
* \brief function to process the last block being hashed
* @param state Pointer to the context in which this block should be processed.
* @param block Pointer to the message wich should be hashed.
* @param length is the length of only THIS block in BITS not in bytes!
* bits are big endian, meaning high bits come first.
* if you have a message with bits at the end, the byte must be padded with zeros
*/
void sha256_lastBlock(sha256_ctx_t *state, const void *block, uint16_t length){
uint8_t lb[SHA256_BLOCK_BITS / 8]; /* local block */
uint64_t msg_len;
while(length>=SHA256_BLOCK_BITS){
sha256_nextBlock(state, block);
length -= SHA256_BLOCK_BITS;
block = (uint8_t*)block + SHA256_BLOCK_BYTES;
}
msg_len = state->length;
msg_len *= 512;
msg_len += length;
memcpy (&(lb[0]), block, length / 8);
/* set the final one bit */
if (length & 7){ // if we have single bits at the end
lb[length / 8] = ((uint8_t*)(block))[length / 8];
} else {
lb[length / 8] = 0;
}
lb[length / 8] |= 0x80 >> (length & 7);
length = (length / 8) + 1; /* from now on length contains the number of BYTES in lb*/
/* pad with zeros */
if (length > 64 - 8){ /* not enouth space for 64bit length value */
memset((void*)(&(lb[length])), 0, 64 - length);
sha256_nextBlock(state, lb);
length = 0;
}
memset((void*)(&(lb[length])), 0, 56 - length);
/* store the 64bit length value */
#if defined LITTLE_ENDIAN
/* this is now rolled up */
uint8_t i = 7;
do {
lb[56 + i] = msg_len & 0xff;
msg_len >>= 8;
} while (i--);
#elif defined BIG_ENDIAN
*((uint64_t)&(lb[56])) = state->length;
#endif
sha256_nextBlock(state, lb);
}
/*************************************************************************/
/*
* length in bits!
*/
void sha256(sha256_hash_t *dest, const void *msg, uint32_t length){ /* length could be choosen longer but this is for µC */
sha256_ctx_t s;
sha256_init(&s);
while(length >= SHA256_BLOCK_BITS){
sha256_nextBlock(&s, msg);
msg = (uint8_t*)msg + SHA256_BLOCK_BITS/8;
length -= SHA256_BLOCK_BITS;
}
sha256_lastBlock(&s, msg, length);
sha256_ctx2hash(dest,&s);
}
/*************************************************************************/
void sha256_ctx2hash(sha256_hash_t *dest, const sha256_ctx_t *state){
#if defined LITTLE_ENDIAN
uint8_t i;
for(i = 0; i < 8; ++i){
((uint32_t*)dest)[i] = change_endian32(state->h[i]);
}
#elif BIG_ENDIAN
if (dest != state->h)
memcpy(dest, state->h, SHA256_HASH_BITS/8);
#else
# error unsupported endian type!
#endif
}
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