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Completed the implementation, including testing, and fixed bugs

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This commit is contained in:
Alain Mosnier
2017-12-13 11:12:47 +01:00
parent d676207600
commit 489f5e66b6
6 changed files with 139 additions and 23 deletions
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55
sha-256.c
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@@ -71,6 +71,8 @@ static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state * state)
memcpy(chunk, state->p, state->len);
chunk += state->len;
space_in_chunk = CHUNK_SIZE - state->len;
state->p += state->len;
state->len = 0;
/* If we are here, space_in_chunk is one at minimum. */
if (!state->single_one_delivered) {
@@ -83,21 +85,39 @@ static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state * state)
* Now:
* - either there is enough space left for the total length, and we can conclude,
* - or there is too little space left, and we have to pad the rest of this chunk with zeroes.
* In the latter case, we will conclude at the next pass.
* In the latter case, we will conclude at the next invokation of this function.
*/
if (space_in_chunk >= TOTAL_LEN_LEN) {
const size_t left = space_in_chunk - TOTAL_LEN_LEN;
const size_t len = state->total_len;
const size_t len = state->total_len * 8;
memset(chunk, 0x00, left);
chunk += left;
chunk[0] = (uint8_t) (len >> 56);
chunk[1] = (uint8_t) (len >> 48);
chunk[2] = (uint8_t) (len >> 40);
chunk[3] = (uint8_t) (len >> 32);
chunk[4] = (uint8_t) (len >> 24);
chunk[5] = (uint8_t) (len >> 16);
chunk[6] = (uint8_t) (len >> 8);
if (sizeof len > 4) {
chunk[0] = (uint8_t) (len >> 56);
chunk[1] = (uint8_t) (len >> 48);
chunk[2] = (uint8_t) (len >> 40);
chunk[3] = (uint8_t) (len >> 32);
} else {
chunk[0] = 0;
chunk[1] = 0;
chunk[2] = 0;
chunk[3] = 0;
}
if (sizeof len > 2) {
chunk[4] = (uint8_t) (len >> 24);
chunk[5] = (uint8_t) (len >> 16);
} else {
chunk[4] = 0;
chunk[5] = 0;
}
if (sizeof len > 1) {
chunk[6] = (uint8_t) (len >> 8);
} else {
chunk[6] = 0;
}
chunk[7] = (uint8_t) len;
state->total_len_delivered = 1;
@@ -108,6 +128,13 @@ static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state * state)
return 1;
}
/*
* Limitations:
* - len must be small enough for (8 * len) to fit in len. Otherwise, the results are unpredictable.
* - sizeof size_t is assumed to be either 8, 16, 32 or 64. Otherwise, the results are unpredictable.
* - Since input is a pointer in RAM, the data to hash should be in RAM, which could be a problem
* for large data sizes.
*/
void calc_sha_256(uint8_t hash[32], const void * input, size_t len)
{
/*
@@ -161,8 +188,8 @@ void calc_sha_256(uint8_t hash[32], const void * input, size_t len)
/* Extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array: */
for (int i = 16; i < 64; i++) {
const uint32_t s0 = right_rot(w[i - 15], 7) ^ right_rot(w[i - 15], 18) ^ w[i - 15] >> 3;
const uint32_t s1 = right_rot(w[i - 2], 17) ^ right_rot(w[i - 2], 19) ^ w[i - 2] >> 10;
const uint32_t s0 = right_rot(w[i - 15], 7) ^ right_rot(w[i - 15], 18) ^ (w[i - 15] >> 3);
const uint32_t s1 = right_rot(w[i - 2], 17) ^ right_rot(w[i - 2], 19) ^ (w[i - 2] >> 10);
w[i] = w[i - 16] + s0 + w[i - 7] + s1;
}
@@ -179,10 +206,10 @@ void calc_sha_256(uint8_t hash[32], const void * input, size_t len)
/* Compression function main loop: */
for (int i = 0; i < 64; i++) {
const uint32_t s1 = right_rot(e, 6) ^ right_rot(e, 11) ^ right_rot(e, 25);
const uint32_t ch = e & f ^ ~e & g;
const uint32_t ch = (e & f) ^ (~e & g);
const uint32_t temp1 = h + s1 + ch + k[i] + w[i];
const uint32_t s0 = right_rot(a, 2) ^right_rot(a, 13) ^ right_rot(a, 22);
const uint32_t maj = a & b ^ a & c ^ b & c;
const uint32_t s0 = right_rot(a, 2) ^ right_rot(a, 13) ^ right_rot(a, 22);
const uint32_t maj = (a & b) ^ (a & c) ^ (b & c);
const uint32_t temp2 = s0 + maj;
h = g;