dh_kdf.c revision 325337 
1/* crypto/dh/dh_kdf.c */
2/*
3 * Written by Stephen Henson for the OpenSSL project.
4 */
5/* ====================================================================
6 * Copyright (c) 2013 The OpenSSL Project.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in
17 *    the documentation and/or other materials provided with the
18 *    distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 *    software must display the following acknowledgment:
22 *    "This product includes software developed by the OpenSSL Project
23 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 *    endorse or promote products derived from this software without
27 *    prior written permission. For written permission, please contact
28 *    openssl-core@openssl.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 *    nor may "OpenSSL" appear in their names without prior written
32 *    permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 *    acknowledgment:
36 *    "This product includes software developed by the OpenSSL Project
37 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 */
53
54#include <e_os.h>
55
56#ifndef OPENSSL_NO_CMS
57#include <string.h>
58#include <openssl/dh.h>
59#include <openssl/evp.h>
60#include <openssl/asn1.h>
61#include <openssl/cms.h>
62
63/* Key derivation from X9.42/RFC2631 */
64
65#define DH_KDF_MAX      (1L << 30)
66
67/* Skip past an ASN1 structure: for OBJECT skip content octets too */
68
69static int skip_asn1(unsigned char **pp, long *plen, int exptag)
70{
71    const unsigned char *q = *pp;
72    int i, tag, xclass;
73    long tmplen;
74    i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen);
75    if (i & 0x80)
76        return 0;
77    if (tag != exptag || xclass != V_ASN1_UNIVERSAL)
78        return 0;
79    if (tag == V_ASN1_OBJECT)
80        q += tmplen;
81    *plen -= q - *pp;
82    *pp = (unsigned char *)q;
83    return 1;
84}
85
86/*
87 * Encode the DH shared info structure, return an offset to the counter value
88 * so we can update the structure without reencoding it.
89 */
90
91static int dh_sharedinfo_encode(unsigned char **pder, unsigned char **pctr,
92                                ASN1_OBJECT *key_oid, size_t outlen,
93                                const unsigned char *ukm, size_t ukmlen)
94{
95    unsigned char *p;
96    int derlen;
97    long tlen;
98    /* "magic" value to check offset is sane */
99    static unsigned char ctr[4] = { 0xF3, 0x17, 0x22, 0x53 };
100    X509_ALGOR atmp;
101    ASN1_OCTET_STRING ctr_oct, ukm_oct, *pukm_oct;
102    ASN1_TYPE ctr_atype;
103    if (ukmlen > DH_KDF_MAX || outlen > DH_KDF_MAX)
104        return 0;
105    ctr_oct.data = ctr;
106    ctr_oct.length = 4;
107    ctr_oct.flags = 0;
108    ctr_oct.type = V_ASN1_OCTET_STRING;
109    ctr_atype.type = V_ASN1_OCTET_STRING;
110    ctr_atype.value.octet_string = &ctr_oct;
111    atmp.algorithm = key_oid;
112    atmp.parameter = &ctr_atype;
113    if (ukm) {
114        ukm_oct.type = V_ASN1_OCTET_STRING;
115        ukm_oct.flags = 0;
116        ukm_oct.data = (unsigned char *)ukm;
117        ukm_oct.length = ukmlen;
118        pukm_oct = &ukm_oct;
119    } else
120        pukm_oct = NULL;
121    derlen = CMS_SharedInfo_encode(pder, &atmp, pukm_oct, outlen);
122    if (derlen <= 0)
123        return 0;
124    p = *pder;
125    tlen = derlen;
126    if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
127        return 0;
128    if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
129        return 0;
130    if (!skip_asn1(&p, &tlen, V_ASN1_OBJECT))
131        return 0;
132    if (!skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING))
133        return 0;
134    if (CRYPTO_memcmp(p, ctr, 4))
135        return 0;
136    *pctr = p;
137    return derlen;
138}
139
140int DH_KDF_X9_42(unsigned char *out, size_t outlen,
141                 const unsigned char *Z, size_t Zlen,
142                 ASN1_OBJECT *key_oid,
143                 const unsigned char *ukm, size_t ukmlen, const EVP_MD *md)
144{
145    EVP_MD_CTX mctx;
146    int rv = 0;
147    unsigned int i;
148    size_t mdlen;
149    unsigned char *der = NULL, *ctr;
150    int derlen;
151    if (Zlen > DH_KDF_MAX)
152        return 0;
153    mdlen = EVP_MD_size(md);
154    EVP_MD_CTX_init(&mctx);
155    derlen = dh_sharedinfo_encode(&der, &ctr, key_oid, outlen, ukm, ukmlen);
156    if (derlen == 0)
157        goto err;
158    for (i = 1;; i++) {
159        unsigned char mtmp[EVP_MAX_MD_SIZE];
160        EVP_DigestInit_ex(&mctx, md, NULL);
161        if (!EVP_DigestUpdate(&mctx, Z, Zlen))
162            goto err;
163        ctr[3] = i & 0xFF;
164        ctr[2] = (i >> 8) & 0xFF;
165        ctr[1] = (i >> 16) & 0xFF;
166        ctr[0] = (i >> 24) & 0xFF;
167        if (!EVP_DigestUpdate(&mctx, der, derlen))
168            goto err;
169        if (outlen >= mdlen) {
170            if (!EVP_DigestFinal(&mctx, out, NULL))
171                goto err;
172            outlen -= mdlen;
173            if (outlen == 0)
174                break;
175            out += mdlen;
176        } else {
177            if (!EVP_DigestFinal(&mctx, mtmp, NULL))
178                goto err;
179            memcpy(out, mtmp, outlen);
180            OPENSSL_cleanse(mtmp, mdlen);
181            break;
182        }
183    }
184    rv = 1;
185 err:
186    if (der)
187        OPENSSL_free(der);
188    EVP_MD_CTX_cleanup(&mctx);
189    return rv;
190}
191#endif
192