| /* |
| * SHA1-based key derivation function (PBKDF2) for IEEE 802.11i |
| * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi> |
| * |
| * This software may be distributed under the terms of the BSD license. |
| * See README for more details. |
| */ |
| |
| #include "includes.h" |
| |
| #include "common.h" |
| #include "sha1.h" |
| |
| static int pbkdf2_sha1_f(const char *passphrase, const u8 *ssid, |
| size_t ssid_len, int iterations, unsigned int count, |
| u8 *digest) |
| { |
| unsigned char tmp[SHA1_MAC_LEN], tmp2[SHA1_MAC_LEN]; |
| int i, j; |
| unsigned char count_buf[4]; |
| const u8 *addr[2]; |
| size_t len[2]; |
| size_t passphrase_len = os_strlen(passphrase); |
| |
| addr[0] = ssid; |
| len[0] = ssid_len; |
| addr[1] = count_buf; |
| len[1] = 4; |
| |
| /* F(P, S, c, i) = U1 xor U2 xor ... Uc |
| * U1 = PRF(P, S || i) |
| * U2 = PRF(P, U1) |
| * Uc = PRF(P, Uc-1) |
| */ |
| |
| count_buf[0] = (count >> 24) & 0xff; |
| count_buf[1] = (count >> 16) & 0xff; |
| count_buf[2] = (count >> 8) & 0xff; |
| count_buf[3] = count & 0xff; |
| if (hmac_sha1_vector((u8 *) passphrase, passphrase_len, 2, addr, len, |
| tmp)) |
| return -1; |
| os_memcpy(digest, tmp, SHA1_MAC_LEN); |
| |
| for (i = 1; i < iterations; i++) { |
| if (hmac_sha1((u8 *) passphrase, passphrase_len, tmp, |
| SHA1_MAC_LEN, tmp2)) |
| return -1; |
| os_memcpy(tmp, tmp2, SHA1_MAC_LEN); |
| for (j = 0; j < SHA1_MAC_LEN; j++) |
| digest[j] ^= tmp2[j]; |
| } |
| |
| return 0; |
| } |
| |
| |
| /** |
| * pbkdf2_sha1 - SHA1-based key derivation function (PBKDF2) for IEEE 802.11i |
| * @passphrase: ASCII passphrase |
| * @ssid: SSID |
| * @ssid_len: SSID length in bytes |
| * @iterations: Number of iterations to run |
| * @buf: Buffer for the generated key |
| * @buflen: Length of the buffer in bytes |
| * Returns: 0 on success, -1 of failure |
| * |
| * This function is used to derive PSK for WPA-PSK. For this protocol, |
| * iterations is set to 4096 and buflen to 32. This function is described in |
| * IEEE Std 802.11-2004, Clause H.4. The main construction is from PKCS#5 v2.0. |
| */ |
| int pbkdf2_sha1(const char *passphrase, const u8 *ssid, size_t ssid_len, |
| int iterations, u8 *buf, size_t buflen) |
| { |
| unsigned int count = 0; |
| unsigned char *pos = buf; |
| size_t left = buflen, plen; |
| unsigned char digest[SHA1_MAC_LEN]; |
| |
| while (left > 0) { |
| count++; |
| if (pbkdf2_sha1_f(passphrase, ssid, ssid_len, iterations, |
| count, digest)) |
| return -1; |
| plen = left > SHA1_MAC_LEN ? SHA1_MAC_LEN : left; |
| os_memcpy(pos, digest, plen); |
| pos += plen; |
| left -= plen; |
| } |
| |
| return 0; |
| } |