1 /* Implementation of Password-Based Cryptography as per PKCS#5
2 * Copyright (C) 2002,2003 Simon Josefsson
3 * Copyright (C) 2004 Free Software Foundation
6 * Copyright (C) 2004, Clemens Fruhwirth <clemens@endorphin.org>
7 * Copyright (C) 2009-2011, Red Hat, Inc. All rights reserved.
9 * This file is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
14 * This file is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this file; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
25 #include <netinet/in.h>
31 #include "crypto_backend.h"
34 static volatile uint64_t __PBKDF2_global_j = 0;
35 static volatile uint64_t __PBKDF2_performance = 0;
40 * PBKDF2 applies a pseudorandom function (see Appendix B.1 for an
41 * example) to derive keys. The length of the derived key is essentially
42 * unbounded. (However, the maximum effective search space for the
43 * derived key may be limited by the structure of the underlying
44 * pseudorandom function. See Appendix B.1 for further discussion.)
45 * PBKDF2 is recommended for new applications.
47 * PBKDF2 (P, S, c, dkLen)
49 * Options: PRF underlying pseudorandom function (hLen
50 * denotes the length in octets of the
51 * pseudorandom function output)
53 * Input: P password, an octet string (ASCII or UTF-8)
54 * S salt, an octet string
55 * c iteration count, a positive integer
56 * dkLen intended length in octets of the derived
57 * key, a positive integer, at most
60 * Output: DK derived key, a dkLen-octet string
63 #define MAX_PRF_BLOCK_LEN 80
65 static int pkcs5_pbkdf2(const char *hash,
66 const char *P, size_t Plen,
67 const char *S, size_t Slen,
68 unsigned int c, unsigned int dkLen,
69 char *DK, int perfcheck)
71 struct crypt_hmac *hmac;
72 char U[MAX_PRF_BLOCK_LEN];
73 char T[MAX_PRF_BLOCK_LEN];
74 int i, k, rc = -EINVAL;
75 unsigned int u, hLen, l, r;
76 size_t tmplen = Slen + 4;
83 hLen = crypt_hmac_size(hash);
84 if (hLen == 0 || hLen > MAX_PRF_BLOCK_LEN)
97 * 1. If dkLen > (2^32 - 1) * hLen, output "derived key too long" and
101 if (dkLen > 4294967295U)
105 * 2. Let l be the number of hLen-octet blocks in the derived key,
106 * rounding up, and let r be the number of octets in the last
109 * l = CEIL (dkLen / hLen) ,
110 * r = dkLen - (l - 1) * hLen .
112 * Here, CEIL (x) is the "ceiling" function, i.e. the smallest
113 * integer greater than, or equal to, x.
119 r = dkLen - (l - 1) * hLen;
122 * 3. For each block of the derived key apply the function F defined
123 * below to the password P, the salt S, the iteration count c, and
124 * the block index to compute the block:
126 * T_1 = F (P, S, c, 1) ,
127 * T_2 = F (P, S, c, 2) ,
129 * T_l = F (P, S, c, l) ,
131 * where the function F is defined as the exclusive-or sum of the
132 * first c iterates of the underlying pseudorandom function PRF
133 * applied to the password P and the concatenation of the salt S
134 * and the block index i:
136 * F (P, S, c, i) = U_1 \xor U_2 \xor ... \xor U_c
140 * U_1 = PRF (P, S || INT (i)) ,
141 * U_2 = PRF (P, U_1) ,
143 * U_c = PRF (P, U_{c-1}) .
145 * Here, INT (i) is a four-octet encoding of the integer i, most
146 * significant octet first.
148 * 4. Concatenate the blocks and extract the first dkLen octets to
149 * produce a derived key DK:
151 * DK = T_1 || T_2 || ... || T_l<0..r-1>
153 * 5. Output the derived key DK.
155 * Note. The construction of the function F follows a "belt-and-
156 * suspenders" approach. The iterates U_i are computed recursively to
157 * remove a degree of parallelism from an opponent; they are exclusive-
158 * ored together to reduce concerns about the recursion degenerating
159 * into a small set of values.
163 if (crypt_hmac_init(&hmac, hash, P, Plen))
166 for (i = 1; (uint) i <= l; i++) {
169 for (u = 1; u <= c ; u++) {
171 memcpy(tmp, S, Slen);
172 tmp[Slen + 0] = (i & 0xff000000) >> 24;
173 tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
174 tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
175 tmp[Slen + 3] = (i & 0x000000ff) >> 0;
177 if (crypt_hmac_write(hmac, tmp, tmplen))
180 if (crypt_hmac_write(hmac, U, hLen))
184 if (crypt_hmac_final(hmac, U, hLen))
187 for (k = 0; (uint) k < hLen; k++)
190 if (perfcheck && __PBKDF2_performance) {
199 memcpy(DK + (i - 1) * hLen, T, (uint) i == l ? r : hLen);
203 crypt_hmac_destroy(hmac);
207 int PBKDF2_HMAC(const char *hash,
208 const char *password, size_t passwordLen,
209 const char *salt, size_t saltLen, unsigned int iterations,
210 char *dKey, size_t dKeyLen)
212 return pkcs5_pbkdf2(hash, password, passwordLen, salt, saltLen,
213 iterations, (unsigned int)dKeyLen, dKey, 0);
216 int PBKDF2_HMAC_ready(const char *hash)
218 if (crypt_hmac_size(hash) < 20)
224 static void sigvtalarm(int foo __attribute__((unused)))
226 __PBKDF2_performance = __PBKDF2_global_j;
229 /* This code benchmarks PBKDF2 and returns iterations/second using wth specified hash */
230 int PBKDF2_performance_check(const char *hash, uint64_t *iter)
236 if (__PBKDF2_global_j)
239 if (PBKDF2_HMAC_ready(hash) < 0)
242 /* If crypto backend is not implemented in userspace,
243 * but uses some kernel part, we must measure also time
244 * spent in kernel. */
245 if (crypt_backend_flags() & CRYPT_BACKEND_KERNEL) {
246 timer_type = ITIMER_PROF;
247 signal(SIGPROF,sigvtalarm);
249 timer_type = ITIMER_VIRTUAL;
250 signal(SIGVTALRM,sigvtalarm);
253 it.it_interval.tv_usec = 0;
254 it.it_interval.tv_sec = 0;
255 it.it_value.tv_usec = 0;
256 it.it_value.tv_sec = 1;
257 if (setitimer(timer_type, &it, NULL) < 0)
260 r = pkcs5_pbkdf2(hash, "foo", 3, "bar", 3, ~(0U), 1, &buf, 1);
262 *iter = __PBKDF2_performance;
263 __PBKDF2_global_j = 0;
264 __PBKDF2_performance = 0;