Completed the implementation, including testing, and fixed bugs

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

2
.gitignore vendored
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@ -1 +1,3 @@
*~ *~
*.o
test

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@ -1,3 +1,5 @@
CFLAGS = -Wall -Wextra -Wpedantic
test: test.o sha-256.o test: test.o sha-256.o
.PHONY: clean .PHONY: clean

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@ -1,2 +1,27 @@
# sha-2 # sha-2
SHA-2 algorithm implementations
## Contents
SHA-2 algorithm implementations.
At the moment, only a SHA-256 is implemented.
## Design criteria
- Easy to test, include in any project, compile and link.
- ANSI C with as little specific C99 as possible (e.g. extended
integer types are used, but not bool).
- Portable. Makes no assumptions on the target system's endianess or
word size.
- The SHA-256 implementation is a straightforward implementation of
the algorithm specified on
[Wikipedia](https://en.wikipedia.org/wiki/SHA-2). At the moment,
no effort at all has been put in optimization.
## License
This repository is made available in the public domain. See [LICENSE
FILE](LICENSE).

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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); memcpy(chunk, state->p, state->len);
chunk += state->len; chunk += state->len;
space_in_chunk = CHUNK_SIZE - 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 we are here, space_in_chunk is one at minimum. */
if (!state->single_one_delivered) { if (!state->single_one_delivered) {
@ -83,21 +85,39 @@ static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state * state)
* Now: * Now:
* - either there is enough space left for the total length, and we can conclude, * - 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. * - 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) { if (space_in_chunk >= TOTAL_LEN_LEN) {
const size_t left = 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); memset(chunk, 0x00, left);
chunk += left; chunk += left;
if (sizeof len > 4) {
chunk[0] = (uint8_t) (len >> 56); chunk[0] = (uint8_t) (len >> 56);
chunk[1] = (uint8_t) (len >> 48); chunk[1] = (uint8_t) (len >> 48);
chunk[2] = (uint8_t) (len >> 40); chunk[2] = (uint8_t) (len >> 40);
chunk[3] = (uint8_t) (len >> 32); 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[4] = (uint8_t) (len >> 24);
chunk[5] = (uint8_t) (len >> 16); chunk[5] = (uint8_t) (len >> 16);
} else {
chunk[4] = 0;
chunk[5] = 0;
}
if (sizeof len > 1) {
chunk[6] = (uint8_t) (len >> 8); chunk[6] = (uint8_t) (len >> 8);
} else {
chunk[6] = 0;
}
chunk[7] = (uint8_t) len; chunk[7] = (uint8_t) len;
state->total_len_delivered = 1; state->total_len_delivered = 1;
@ -108,6 +128,13 @@ static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state * state)
return 1; 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) 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: */ /* 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++) { 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 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 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; 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: */ /* Compression function main loop: */
for (int i = 0; i < 64; i++) { 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 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 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 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 maj = (a & b) ^ (a & c) ^ (b & c);
const uint32_t temp2 = s0 + maj; const uint32_t temp2 = s0 + maj;
h = g; h = g;

71
test.c
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@ -1,14 +1,75 @@
#include <stdint.h> #include <stdint.h>
#include <stdio.h> #include <stdio.h>
#include <string.h>
#include "sha-256.h" #include "sha-256.h"
int main() struct vector {
const char *input;
const char *output;
};
static const struct vector VECTORS[] = {
{
"",
"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
},
{
"abc",
"ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
},
{
"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
"a8ae6e6ee929abea3afcfc5258c8ccd6f85273e0d4626d26c7279f3250f77c8e"
},
{
"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcde",
"057ee79ece0b9a849552ab8d3c335fe9a5f1c46ef5f1d9b190c295728628299c"
},
{
"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0",
"2a6ad82f3620d3ebe9d678c812ae12312699d673240d5be8fac0910a70000d93"
},
{
"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
"248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1"
},
{
"abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoi"
"jklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu",
"cf5b16a778af8380036ce59e7b0492370b249b11e8f07a51afac45037afee9d1"
}
};
static void hash_to_string(char string[65], const uint8_t hash[32])
{
for (size_t i = 0; i < 32; i++) {
string += sprintf(string, "%02x", hash[i]);
}
}
static void test(const char input[], const char output[])
{ {
uint8_t hash[32]; uint8_t hash[32];
calc_sha_256(hash, "hello\n", 6); char hash_string[65];
for (size_t i = 0; i < sizeof hash; i++) { calc_sha_256(hash, input, strlen(input));
printf("%02x", hash[i]); hash_to_string(hash_string, hash);
printf("input: %s\n", input);
printf("hash : %s\n", hash_string);
if (strcmp(output, hash_string)) {
printf("FAILURE!\n\n");
} else {
printf("SUCCESS!\n\n");
} }
printf("\n"); }
int main(void)
{
printf("%zu\n", sizeof (size_t));
for (size_t i = 0; i < (sizeof VECTORS / sizeof (struct vector)); i++) {
const struct vector *vector = &VECTORS[i];
test(vector->input, vector->output);
}
return 0;
} }

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hello