source: lib/sha1.c @ da0202a

#include "sha1.h"
#include <string.h>
#include <stdio.h>


void sha1_init(sha1_state_t *ctx)
{
        *ctx = g_checksum_new(G_CHECKSUM_SHA1);
}

void sha1_append(sha1_state_t *ctx, const guint8 * message_array, guint len)
{
        g_checksum_update(*ctx, message_array, len);
}

void sha1_finish(sha1_state_t *ctx, guint8 digest[SHA1_HASH_SIZE])
{
        gsize digest_len = SHA1_HASH_SIZE;

        g_checksum_get_digest(*ctx, digest, &digest_len);
        g_checksum_free(*ctx);
}

#define HMAC_BLOCK_SIZE 64

void b_hmac(GChecksumType checksum_type, const char *key_, size_t key_len,
            const char *payload, size_t payload_len, guint8 **digest)
{
        GChecksum *checksum;
        size_t hash_len;
        guint8 *hash;
        guint8 key[HMAC_BLOCK_SIZE + 1];
        int i;

        hash_len = g_checksum_type_get_length(checksum_type);

        if (hash_len == (size_t) -1) {
                return;
        }

        hash = g_malloc(hash_len);

        if (key_len == 0) {
                key_len = strlen(key_);
        }
        if (payload_len == 0) {
                payload_len = strlen(payload);
        }

        /* Create K. If our current key is >64 chars we have to hash it,
           otherwise just pad. */
        memset(key, 0, HMAC_BLOCK_SIZE + 1);
        if (key_len > HMAC_BLOCK_SIZE) {
                checksum = g_checksum_new(checksum_type);
                g_checksum_update(checksum, (guint8 *) key_, key_len);
                g_checksum_get_digest(checksum, key, &hash_len);
                g_checksum_free(checksum);
        } else {
                memcpy(key, key_, key_len);
        }

        /* Inner part: H(K XOR 0x36, text) */
        checksum = g_checksum_new(checksum_type);
        for (i = 0; i < HMAC_BLOCK_SIZE; i++) {
                key[i] ^= 0x36;
        }
        g_checksum_update(checksum, key, HMAC_BLOCK_SIZE);
        g_checksum_update(checksum, (const guint8 *) payload, payload_len);
        g_checksum_get_digest(checksum, hash, &hash_len);
        g_checksum_free(checksum);

        /* Final result: H(K XOR 0x5C, inner stuff) */
        checksum = g_checksum_new(checksum_type);
        for (i = 0; i < HMAC_BLOCK_SIZE; i++) {
                key[i] ^= 0x36 ^ 0x5c;
        }
        g_checksum_update(checksum, key, HMAC_BLOCK_SIZE);
        g_checksum_update(checksum, hash, hash_len);
        g_checksum_get_digest(checksum, *digest, &hash_len);
        g_checksum_free(checksum);

        g_free(hash);
}

void sha1_hmac(const char *key_, size_t key_len, const char *payload, size_t payload_len, guint8 digest[SHA1_HASH_SIZE])
{
        b_hmac(G_CHECKSUM_SHA1, key_, key_len, payload, payload_len, &digest);
}


/* I think this follows the scheme described on:
   http://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29
   My random data comes from a SHA1 generator but hey, it's random enough for
   me, and RFC 4122 looks way more complicated than I need this to be.

   Returns a value that must be free()d. */
char *sha1_random_uuid(sha1_state_t * context)
{
        guint8 dig[SHA1_HASH_SIZE];
        char *ret = g_new0(char, 40);   /* 36 chars + \0 */
        int i, p;

        sha1_finish(context, dig);
        for (p = i = 0; i < 16; i++) {
                if (i == 4 || i == 6 || i == 8 || i == 10) {
                        ret[p++] = '-';
                }
                if (i == 6) {
                        dig[i] = (dig[i] & 0x0f) | 0x40;
                }
                if (i == 8) {
                        dig[i] = (dig[i] & 0x30) | 0x80;
                }

                sprintf(ret + p, "%02x", dig[i]);
                p += 2;
        }
        ret[p] = '\0';

        return ret;
}