diff --git a/.gitignore b/.gitignore
index e4e5f6c..6587b2f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
-*~
\ No newline at end of file
+*~
+*.o
+test
diff --git a/Makefile b/Makefile
index dc1b47a..fd721b2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,5 @@
+CFLAGS = -Wall -Wextra -Wpedantic
+
test: test.o sha-256.o
.PHONY: clean
diff --git a/README.md b/README.md
index c0cfd7f..966db6e 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,27 @@
# 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).
diff --git a/sha-256.c b/sha-256.c
index 852ff30..26c7698 100644
--- a/sha-256.c
+++ b/sha-256.c
@@ -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;
diff --git a/test.c b/test.c
index c4f843a..5acec4c 100644
--- a/test.c
+++ b/test.c
@@ -1,14 +1,75 @@
#include <stdint.h>
#include <stdio.h>
+#include <string.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];
- calc_sha_256(hash, "hello\n", 6);
- for (size_t i = 0; i < sizeof hash; i++) {
- printf("%02x", hash[i]);
- }
- printf("\n");
+ char hash_string[65];
+ calc_sha_256(hash, input, strlen(input));
+ 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");
+ }
+}
+
+
+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;
}
diff --git a/tmp.txt b/tmp.txt
deleted file mode 100644
index ce01362..0000000
--- a/tmp.txt
+++ /dev/null
@@ -1 +0,0 @@
-hello