wpa_supplicant_node: sha1-pbkdf2.c Source File

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00001 /*
00002  * SHA1-based key derivation function (PBKDF2) for IEEE 802.11i
00003  * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
00004  *
00005  * This program is free software; you can redistribute it and/or modify
00006  * it under the terms of the GNU General Public License version 2 as
00007  * published by the Free Software Foundation.
00008  *
00009  * Alternatively, this software may be distributed under the terms of BSD
00010  * license.
00011  *
00012  * See README and COPYING for more details.
00013  */
00014 
00015 #include "includes.h"
00016 
00017 #include "common.h"
00018 #include "sha1.h"
00019 #include "md5.h"
00020 #include "crypto.h"
00021 
00022 static int pbkdf2_sha1_f(const char *passphrase, const char *ssid,
00023                          size_t ssid_len, int iterations, unsigned int count,
00024                          u8 *digest)
00025 {
00026         unsigned char tmp[SHA1_MAC_LEN], tmp2[SHA1_MAC_LEN];
00027         int i, j;
00028         unsigned char count_buf[4];
00029         const u8 *addr[2];
00030         size_t len[2];
00031         size_t passphrase_len = os_strlen(passphrase);
00032 
00033         addr[0] = (u8 *) ssid;
00034         len[0] = ssid_len;
00035         addr[1] = count_buf;
00036         len[1] = 4;
00037 
00038         /* F(P, S, c, i) = U1 xor U2 xor ... Uc
00039          * U1 = PRF(P, S || i)
00040          * U2 = PRF(P, U1)
00041          * Uc = PRF(P, Uc-1)
00042          */
00043 
00044         count_buf[0] = (count >> 24) & 0xff;
00045         count_buf[1] = (count >> 16) & 0xff;
00046         count_buf[2] = (count >> 8) & 0xff;
00047         count_buf[3] = count & 0xff;
00048         if (hmac_sha1_vector((u8 *) passphrase, passphrase_len, 2, addr, len,
00049                              tmp))
00050                 return -1;
00051         os_memcpy(digest, tmp, SHA1_MAC_LEN);
00052 
00053         for (i = 1; i < iterations; i++) {
00054                 if (hmac_sha1((u8 *) passphrase, passphrase_len, tmp,
00055                               SHA1_MAC_LEN, tmp2))
00056                         return -1;
00057                 os_memcpy(tmp, tmp2, SHA1_MAC_LEN);
00058                 for (j = 0; j < SHA1_MAC_LEN; j++)
00059                         digest[j] ^= tmp2[j];
00060         }
00061 
00062         return 0;
00063 }
00064 
00065 
00080 int pbkdf2_sha1(const char *passphrase, const char *ssid, size_t ssid_len,
00081                 int iterations, u8 *buf, size_t buflen)
00082 {
00083         unsigned int count = 0;
00084         unsigned char *pos = buf;
00085         size_t left = buflen, plen;
00086         unsigned char digest[SHA1_MAC_LEN];
00087 
00088         while (left > 0) {
00089                 count++;
00090                 if (pbkdf2_sha1_f(passphrase, ssid, ssid_len, iterations,
00091                                   count, digest))
00092                         return -1;
00093                 plen = left > SHA1_MAC_LEN ? SHA1_MAC_LEN : left;
00094                 os_memcpy(pos, digest, plen);
00095                 pos += plen;
00096                 left -= plen;
00097         }
00098 
00099         return 0;
00100 }