source: openpam/trunk/modules/pam_oath/oath_hotp.c @ 623

Last change on this file since 623 was 623, checked in by Dag-Erling Smørgrav, 8 years ago

WIP: OATH module

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 2.6 KB
Line 
1/*-
2 * Copyright (c) 2012-2013 Universitetet i Oslo
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 * 3. The name of the author may not be used to endorse or promote
14 *    products derived from this software without specific prior written
15 *    permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $Id: oath_hotp.c 623 2013-02-25 07:24:51Z des $
30 */
31
32#ifdef HAVE_CONFIG_H
33# include "config.h"
34#endif
35
36#include <openssl/evp.h>
37#include <openssl/hmac.h>
38
39#include <stdint.h>
40
41#include "oath.h"
42
43#define StToNum(St) (St)
44
45static uint32_t
46DT(const uint8_t *String)
47{
48        uint8_t OffsetBits;
49        int Offset;
50        uint32_t P;
51
52        OffsetBits = String[19] & 0x0f;
53        Offset = StToNum(OffsetBits);
54        P = (uint32_t)String[Offset + 0] << 24 |
55            (uint32_t)String[Offset + 1] << 16 |
56            (uint32_t)String[Offset + 2] << 8 |
57            (uint32_t)String[Offset + 3];
58        return (P & 0x7fffffffUL);
59}
60
61unsigned int
62oath_hotp(const uint8_t *K, size_t Klen, uint64_t seq, unsigned int Digit)
63{
64        HMAC_CTX ctx;
65        uint8_t C[8];
66        uint8_t HS[20];
67        unsigned int HSlen;
68        uint32_t Sbits, Snum;
69        unsigned int mod, D;
70
71        for (int i = 7; i >= 0; --i) {
72                C[i] = seq & 0xff;
73                seq >>= 8;
74        }
75
76        /* HS = HMAC-SHA-1(K,C) */
77        HMAC_CTX_init(&ctx);
78        HMAC_Init_ex(&ctx, K, Klen, EVP_sha1(), NULL);
79        HMAC_Update(&ctx, (const uint8_t *)&C, sizeof C);
80        HMAC_Final(&ctx, HS, &HSlen);
81        HMAC_CTX_cleanup(&ctx);
82
83        Sbits = DT(HS);
84        Snum = StToNum(Sbits);
85        for (mod = 1; Digit > 0; --Digit)
86                mod *= 10;
87        D = Snum % mod;
88        return (D);
89}
Note: See TracBrowser for help on using the repository browser.