2 * SHA1-based key derivation function (PBKDF2) for IEEE 802.11i
3 * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Alternatively, this software may be distributed under the terms of BSD
12 * See README and COPYING for more details.
22 static int pbkdf2_sha1_f(const char *passphrase, const char *ssid,
23 size_t ssid_len, int iterations, unsigned int count,
26 unsigned char tmp[SHA1_MAC_LEN], tmp2[SHA1_MAC_LEN];
28 unsigned char count_buf[4];
31 size_t passphrase_len = os_strlen(passphrase);
33 addr[0] = (u8 *) ssid;
38 /* F(P, S, c, i) = U1 xor U2 xor ... Uc
44 count_buf[0] = (count >> 24) & 0xff;
45 count_buf[1] = (count >> 16) & 0xff;
46 count_buf[2] = (count >> 8) & 0xff;
47 count_buf[3] = count & 0xff;
48 if (hmac_sha1_vector((u8 *) passphrase, passphrase_len, 2, addr, len,
51 os_memcpy(digest, tmp, SHA1_MAC_LEN);
53 for (i = 1; i < iterations; i++) {
54 if (hmac_sha1((u8 *) passphrase, passphrase_len, tmp,
57 os_memcpy(tmp, tmp2, SHA1_MAC_LEN);
58 for (j = 0; j < SHA1_MAC_LEN; j++)
67 * pbkdf2_sha1 - SHA1-based key derivation function (PBKDF2) for IEEE 802.11i
68 * @passphrase: ASCII passphrase
70 * @ssid_len: SSID length in bytes
71 * @iterations: Number of iterations to run
72 * @buf: Buffer for the generated key
73 * @buflen: Length of the buffer in bytes
74 * Returns: 0 on success, -1 of failure
76 * This function is used to derive PSK for WPA-PSK. For this protocol,
77 * iterations is set to 4096 and buflen to 32. This function is described in
78 * IEEE Std 802.11-2004, Clause H.4. The main construction is from PKCS#5 v2.0.
80 int pbkdf2_sha1(const char *passphrase, const char *ssid, size_t ssid_len,
81 int iterations, u8 *buf, size_t buflen)
83 unsigned int count = 0;
84 unsigned char *pos = buf;
85 size_t left = buflen, plen;
86 unsigned char digest[SHA1_MAC_LEN];
90 if (pbkdf2_sha1_f(passphrase, ssid, ssid_len, iterations,
93 plen = left > SHA1_MAC_LEN ? SHA1_MAC_LEN : left;
94 os_memcpy(pos, digest, plen);