1 /*-
2  * Copyright 2005,2007,2009 Colin Percival
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <limits.h>
28 #include <stdint.h>
29 #include <stdlib.h>
30 #include <string.h>
31 
32 #include <sys/types.h>
33 
34 #include "core.h"
35 #include "crypto_auth_hmacsha256.h"
36 #include "crypto_pwhash_scryptsalsa208sha256.h"
37 #include "pbkdf2-sha256.h"
38 #include "private/common.h"
39 #include "utils.h"
40 
41 /**
42  * PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, c, buf, dkLen):
43  * Compute PBKDF2(passwd, salt, c, dkLen) using HMAC-SHA256 as the PRF, and
44  * write the output to buf.  The value dkLen must be at most 32 * (2^32 - 1).
45  */
46 void
47 PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen, const uint8_t *salt,
48               size_t saltlen, uint64_t c, uint8_t *buf, size_t dkLen)
49 {
50     crypto_auth_hmacsha256_state PShctx, hctx;
51     size_t                       i;
52     uint8_t                      ivec[4];
53     uint8_t                      U[32];
54     uint8_t                      T[32];
55     uint64_t                     j;
56     int                          k;
57     size_t                       clen;
58 
59 #if SIZE_MAX > 0x1fffffffe0ULL
60     COMPILER_ASSERT(crypto_pwhash_scryptsalsa208sha256_BYTES_MAX
61                     <= 0x1fffffffe0ULL);
62     if (dkLen > 0x1fffffffe0ULL) {
63         sodium_misuse(); /* LCOV_EXCL_LINE */
64     }
65 #endif
66     crypto_auth_hmacsha256_init(&PShctx, passwd, passwdlen);
67     crypto_auth_hmacsha256_update(&PShctx, salt, saltlen);
68 
69     for (i = 0; i * 32 < dkLen; i++) {
70         STORE32_BE(ivec, (uint32_t)(i + 1));
71         memcpy(&hctx, &PShctx, sizeof(crypto_auth_hmacsha256_state));
72         crypto_auth_hmacsha256_update(&hctx, ivec, 4);
73         crypto_auth_hmacsha256_final(&hctx, U);
74 
75         memcpy(T, U, 32);
76         /* LCOV_EXCL_START */
77         for (j = 2; j <= c; j++) {
78             crypto_auth_hmacsha256_init(&hctx, passwd, passwdlen);
79             crypto_auth_hmacsha256_update(&hctx, U, 32);
80             crypto_auth_hmacsha256_final(&hctx, U);
81 
82             for (k = 0; k < 32; k++) {
83                 T[k] ^= U[k];
84             }
85         }
86         /* LCOV_EXCL_STOP */
87 
88         clen = dkLen - i * 32;
89         if (clen > 32) {
90             clen = 32;
91         }
92         memcpy(&buf[i * 32], T, clen);
93     }
94     sodium_memzero((void *) &PShctx, sizeof PShctx);
95 }
96