/*      $OpenBSD: hmac_sha1.c,v 1.1 2012/10/09 12:36:50 jsing Exp $     */

/*-
 * Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>

#include <lib/libsa/stand.h>

#include "hmac_sha1.h"

/*
 * HMAC-SHA-1 (from RFC 2202).
 */
void
hmac_sha1(const u_int8_t *text, size_t text_len, const u_int8_t *key,
    size_t key_len, u_int8_t digest[SHA1_DIGEST_LENGTH])
{
        SHA1_CTX ctx;
        u_int8_t k_pad[SHA1_BLOCK_LENGTH];
        u_int8_t tk[SHA1_DIGEST_LENGTH];
        int i;

        if (key_len > SHA1_BLOCK_LENGTH) {
                SHA1Init(&ctx);
                SHA1Update(&ctx, key, key_len);
                SHA1Final(tk, &ctx);

                key = tk;
                key_len = SHA1_DIGEST_LENGTH;
        }

        bzero(k_pad, sizeof k_pad);
        bcopy(key, k_pad, key_len);
        for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
                k_pad[i] ^= 0x36;

        SHA1Init(&ctx);
        SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
        SHA1Update(&ctx, text, text_len);
        SHA1Final(digest, &ctx);

        bzero(k_pad, sizeof k_pad);
        bcopy(key, k_pad, key_len);
        for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
                k_pad[i] ^= 0x5c;

        SHA1Init(&ctx);
        SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
        SHA1Update(&ctx, digest, SHA1_DIGEST_LENGTH);
        SHA1Final(digest, &ctx);
}