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/* Implementation of Password-Based Cryptography as per PKCS#5
* Copyright (C) 2002,2003 Simon Josefsson
* Copyright (C) 2004 Free Software Foundation
*
* LUKS code
* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
* Copyright (C) 2009 Red Hat, Inc. All rights reserved.
*
* This file is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This file is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this file; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <netinet/in.h>
#include <errno.h>
#include <signal.h>
#include <alloca.h>
#include <sys/time.h>
#include <gcrypt.h>
static volatile uint64_t __PBKDF2_global_j = 0;
static volatile uint64_t __PBKDF2_performance = 0;
int init_crypto(void);
/*
* 5.2 PBKDF2
*
* PBKDF2 applies a pseudorandom function (see Appendix B.1 for an
* example) to derive keys. The length of the derived key is essentially
* unbounded. (However, the maximum effective search space for the
* derived key may be limited by the structure of the underlying
* pseudorandom function. See Appendix B.1 for further discussion.)
* PBKDF2 is recommended for new applications.
*
* PBKDF2 (P, S, c, dkLen)
*
* Options: PRF underlying pseudorandom function (hLen
* denotes the length in octets of the
* pseudorandom function output)
*
* Input: P password, an octet string (ASCII or UTF-8)
* S salt, an octet string
* c iteration count, a positive integer
* dkLen intended length in octets of the derived
* key, a positive integer, at most
* (2^32 - 1) * hLen
*
* Output: DK derived key, a dkLen-octet string
*/
#define MAX_PRF_BLOCK_LEN 80
static int pkcs5_pbkdf2(const char *hash,
const char *P, size_t Plen,
const char *S, size_t Slen,
unsigned int c, unsigned int dkLen,
char *DK, int perfcheck)
{
gcry_md_hd_t prf;
char U[MAX_PRF_BLOCK_LEN];
char T[MAX_PRF_BLOCK_LEN];
int PRF, i, k, rc = -EINVAL;
unsigned int u, hLen, l, r;
unsigned char *p;
size_t tmplen = Slen + 4;
char *tmp;
tmp = alloca(tmplen);
if (tmp == NULL)
return -ENOMEM;
if (init_crypto())
return -ENOSYS;
PRF = gcry_md_map_name(hash);
if (PRF == 0)
return -EINVAL;
hLen = gcry_md_get_algo_dlen(PRF);
if (hLen == 0 || hLen > MAX_PRF_BLOCK_LEN)
return -EINVAL;
if (c == 0)
return -EINVAL;
if (dkLen == 0)
return -EINVAL;
/*
*
* Steps:
*
* 1. If dkLen > (2^32 - 1) * hLen, output "derived key too long" and
* stop.
*/
if (dkLen > 4294967295U)
return -EINVAL;
/*
* 2. Let l be the number of hLen-octet blocks in the derived key,
* rounding up, and let r be the number of octets in the last
* block:
*
* l = CEIL (dkLen / hLen) ,
* r = dkLen - (l - 1) * hLen .
*
* Here, CEIL (x) is the "ceiling" function, i.e. the smallest
* integer greater than, or equal to, x.
*/
l = dkLen / hLen;
if (dkLen % hLen)
l++;
r = dkLen - (l - 1) * hLen;
/*
* 3. For each block of the derived key apply the function F defined
* below to the password P, the salt S, the iteration count c, and
* the block index to compute the block:
*
* T_1 = F (P, S, c, 1) ,
* T_2 = F (P, S, c, 2) ,
* ...
* T_l = F (P, S, c, l) ,
*
* where the function F is defined as the exclusive-or sum of the
* first c iterates of the underlying pseudorandom function PRF
* applied to the password P and the concatenation of the salt S
* and the block index i:
*
* F (P, S, c, i) = U_1 \xor U_2 \xor ... \xor U_c
*
* where
*
* U_1 = PRF (P, S || INT (i)) ,
* U_2 = PRF (P, U_1) ,
* ...
* U_c = PRF (P, U_{c-1}) .
*
* Here, INT (i) is a four-octet encoding of the integer i, most
* significant octet first.
*
* 4. Concatenate the blocks and extract the first dkLen octets to
* produce a derived key DK:
*
* DK = T_1 || T_2 || ... || T_l<0..r-1>
*
* 5. Output the derived key DK.
*
* Note. The construction of the function F follows a "belt-and-
* suspenders" approach. The iterates U_i are computed recursively to
* remove a degree of parallelism from an opponent; they are exclusive-
* ored together to reduce concerns about the recursion degenerating
* into a small set of values.
*
*/
if(gcry_md_open(&prf, PRF, GCRY_MD_FLAG_HMAC))
return -EINVAL;
if (gcry_md_setkey(prf, P, Plen))
goto out;
for (i = 1; (uint) i <= l; i++) {
memset(T, 0, hLen);
for (u = 1; u <= c ; u++) {
gcry_md_reset(prf);
if (u == 1) {
memcpy(tmp, S, Slen);
tmp[Slen + 0] = (i & 0xff000000) >> 24;
tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
tmp[Slen + 3] = (i & 0x000000ff) >> 0;
gcry_md_write(prf, tmp, tmplen);
} else {
gcry_md_write(prf, U, hLen);
}
p = gcry_md_read(prf, PRF);
if (p == NULL)
goto out;
memcpy(U, p, hLen);
for (k = 0; (uint) k < hLen; k++)
T[k] ^= U[k];
if (perfcheck && __PBKDF2_performance) {
rc = 0;
goto out;
}
if (perfcheck)
__PBKDF2_global_j++;
}
memcpy(DK + (i - 1) * hLen, T, (uint) i == l ? r : hLen);
}
rc = 0;
out:
gcry_md_close(prf);
return rc;
}
int PBKDF2_HMAC(const char *hash,
const char *password, size_t passwordLen,
const char *salt, size_t saltLen, unsigned int iterations,
char *dKey, size_t dKeyLen)
{
return pkcs5_pbkdf2(hash, password, passwordLen, salt, saltLen,
iterations, (unsigned int)dKeyLen, dKey, 0);
}
int PBKDF2_HMAC_ready(const char *hash)
{
int hash_id = gcry_md_map_name(hash);
if (!hash_id)
return -EINVAL;
/* Used hash must have at least 160 bits */
if (gcry_md_get_algo_dlen(hash_id) < 20)
return -EINVAL;
return 1;
}
static void sigvtalarm(int foo)
{
__PBKDF2_performance = __PBKDF2_global_j;
}
/* This code benchmarks PBKDF2 and returns iterations/second using wth specified hash */
int PBKDF2_performance_check(const char *hash, uint64_t *iter)
{
int r;
char buf;
struct itimerval it;
if (__PBKDF2_global_j)
return -EBUSY;
if (!PBKDF2_HMAC_ready(hash))
return -EINVAL;
signal(SIGVTALRM,sigvtalarm);
it.it_interval.tv_usec = 0;
it.it_interval.tv_sec = 0;
it.it_value.tv_usec = 0;
it.it_value.tv_sec = 1;
if (setitimer (ITIMER_VIRTUAL, &it, NULL) < 0)
return -EINVAL;
r = pkcs5_pbkdf2(hash, "foo", 3, "bar", 3, ~(0U), 1, &buf, 1);
*iter = __PBKDF2_performance;
__PBKDF2_global_j = 0;
__PBKDF2_performance = 0;
return r;
}
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