sha1.c

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/*
 * SHA1 hash implementation and interface functions
 * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "sha1.h"
#include "crypto.h"


int hmac_sha1_vector(const u8 *key, size_t key_len, size_t num_elem,
                     const u8 *addr[], const size_t *len, u8 *mac)
{
        unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
        unsigned char tk[20];
        const u8 *_addr[6];
        size_t _len[6], i;

        if (num_elem > 5) {
                /*
                 * Fixed limit on the number of fragments to avoid having to
                 * allocate memory (which could fail).
                 */
                return -1;
        }

        /* if key is longer than 64 bytes reset it to key = SHA1(key) */
        if (key_len > 64) {
                if (sha1_vector(1, &key, &key_len, tk))
                        return -1;
                key = tk;
                key_len = 20;
        }

        /* the HMAC_SHA1 transform looks like:
         *
         * SHA1(K XOR opad, SHA1(K XOR ipad, text))
         *
         * where K is an n byte key
         * ipad is the byte 0x36 repeated 64 times
         * opad is the byte 0x5c repeated 64 times
         * and text is the data being protected */

        /* start out by storing key in ipad */
        os_memset(k_pad, 0, sizeof(k_pad));
        os_memcpy(k_pad, key, key_len);
        /* XOR key with ipad values */
        for (i = 0; i < 64; i++)
                k_pad[i] ^= 0x36;

        /* perform inner SHA1 */
        _addr[0] = k_pad;
        _len[0] = 64;
        for (i = 0; i < num_elem; i++) {
                _addr[i + 1] = addr[i];
                _len[i + 1] = len[i];
        }
        if (sha1_vector(1 + num_elem, _addr, _len, mac))
                return -1;

        os_memset(k_pad, 0, sizeof(k_pad));
        os_memcpy(k_pad, key, key_len);
        /* XOR key with opad values */
        for (i = 0; i < 64; i++)
                k_pad[i] ^= 0x5c;

        /* perform outer SHA1 */
        _addr[0] = k_pad;
        _len[0] = 64;
        _addr[1] = mac;
        _len[1] = SHA1_MAC_LEN;
        return sha1_vector(2, _addr, _len, mac);
}


int hmac_sha1(const u8 *key, size_t key_len, const u8 *data, size_t data_len,
               u8 *mac)
{
        return hmac_sha1_vector(key, key_len, 1, &data, &data_len, mac);
}


int sha1_prf(const u8 *key, size_t key_len, const char *label,
             const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
{
        u8 counter = 0;
        size_t pos, plen;
        u8 hash[SHA1_MAC_LEN];
        size_t label_len = os_strlen(label) + 1;
        const unsigned char *addr[3];
        size_t len[3];

        addr[0] = (u8 *) label;
        len[0] = label_len;
        addr[1] = data;
        len[1] = data_len;
        addr[2] = &counter;
        len[2] = 1;

        pos = 0;
        while (pos < buf_len) {
                plen = buf_len - pos;
                if (plen >= SHA1_MAC_LEN) {
                        if (hmac_sha1_vector(key, key_len, 3, addr, len,
                                             &buf[pos]))
                                return -1;
                        pos += SHA1_MAC_LEN;
                } else {
                        if (hmac_sha1_vector(key, key_len, 3, addr, len,
                                             hash))
                                return -1;
                        os_memcpy(&buf[pos], hash, plen);
                        break;
                }
                counter++;
        }

        return 0;
}