crypto/dh/dh_kdf.c

   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 <string.h>
  55 #include <openssl/dh.h>
  56 #include <openssl/evp.h>
  57 #include <openssl/asn1.h>
  58 #include <openssl/cms.h>
  59
  60 /* Key derivation from X9.42/RFC2631 */
  61
  62 #define DH_KDF_MAX      (1L << 30)
  63
  64 /* Skip past an ASN1 structure: for OBJECT skip content octets too */
  65
  66 static int skip_asn1(unsigned char **pp, long *plen, int exptag)
  67 {
  68     const unsigned char *q = *pp;
  69     int i, tag, xclass;
  70     long tmplen;
  71     i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen);
  72     if (i & 0x80)
  73         return 0;
  74     if (tag != exptag || xclass != V_ASN1_UNIVERSAL)
  75         return 0;
  76     if (tag == V_ASN1_OBJECT)
  77         q += tmplen;
  78     *plen -= q - *pp;
  79     *pp = (unsigned char *)q;
  80     return 1;
  81 }
  82
  83 /*
  84  * Encode the DH shared info structure, return an offset to the counter value
  85  * so we can update the structure without reencoding it.
  86  */
  87
  88 static int dh_sharedinfo_encode(unsigned char **pder, unsigned char **pctr,
  89                                 ASN1_OBJECT *key_oid, size_t outlen,
  90                                 const unsigned char *ukm, size_t ukmlen)
  91 {
  92     unsigned char *p;
  93     int derlen;
  94     long tlen;
  95     /* "magic" value to check offset is sane */
  96     static unsigned char ctr[4] = { 0xF3, 0x17, 0x22, 0x53 };
  97     X509_ALGOR atmp;
  98     ASN1_OCTET_STRING ctr_oct, ukm_oct, *pukm_oct;
  99     ASN1_TYPE ctr_atype;
 100     if (ukmlen > DH_KDF_MAX || outlen > DH_KDF_MAX)
 101         return 0;
 102     ctr_oct.data = ctr;
 103     ctr_oct.length = 4;
 104     ctr_oct.flags = 0;
 105     ctr_oct.type = V_ASN1_OCTET_STRING;
 106     ctr_atype.type = V_ASN1_OCTET_STRING;
 107     ctr_atype.value.octet_string = &ctr_oct;
 108     atmp.algorithm = key_oid;
 109     atmp.parameter = &ctr_atype;
 110     if (ukm) {
 111         ukm_oct.type = V_ASN1_OCTET_STRING;
 112         ukm_oct.flags = 0;
 113         ukm_oct.data = (unsigned char *)ukm;
 114         ukm_oct.length = ukmlen;
 115         pukm_oct = &ukm_oct;
 116     } else
 117         pukm_oct = NULL;
 118     derlen = CMS_SharedInfo_encode(pder, &atmp, pukm_oct, outlen);
 119     if (derlen <= 0)
 120         return 0;
 121     p = *pder;
 122     tlen = derlen;
 123     if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
 124         return 0;
 125     if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
 126         return 0;
 127     if (!skip_asn1(&p, &tlen, V_ASN1_OBJECT))
 128         return 0;
 129     if (!skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING))
 130         return 0;
 131     if (CRYPTO_memcmp(p, ctr, 4))
 132         return 0;
 133     *pctr = p;
 134     return derlen;
 135 }
 136
 137 int DH_KDF_X9_42(unsigned char *out, size_t outlen,
 138                  const unsigned char *Z, size_t Zlen,
 139                  ASN1_OBJECT *key_oid,
 140                  const unsigned char *ukm, size_t ukmlen, const EVP_MD *md)
 141 {
 142     EVP_MD_CTX mctx;
 143     int rv = 0;
 144     unsigned int i;
 145     size_t mdlen;
 146     unsigned char *der = NULL, *ctr;
 147     int derlen;
 148     if (Zlen > DH_KDF_MAX)
 149         return 0;
 150     mdlen = EVP_MD_size(md);
 151     EVP_MD_CTX_init(&mctx);
 152     derlen = dh_sharedinfo_encode(&der, &ctr, key_oid, outlen, ukm, ukmlen);
 153     if (derlen == 0)
 154         goto err;
 155     for (i = 1;; i++) {
 156         unsigned char mtmp[EVP_MAX_MD_SIZE];
 157         EVP_DigestInit_ex(&mctx, md, NULL);
 158         if (!EVP_DigestUpdate(&mctx, Z, Zlen))
 159             goto err;
 160         ctr[3] = i & 0xFF;
 161         ctr[2] = (i >> 8) & 0xFF;
 162         ctr[1] = (i >> 16) & 0xFF;
 163         ctr[0] = (i >> 24) & 0xFF;
 164         if (!EVP_DigestUpdate(&mctx, der, derlen))
 165             goto err;
 166         if (outlen >= mdlen) {
 167             if (!EVP_DigestFinal(&mctx, out, NULL))
 168                 goto err;
 169             outlen -= mdlen;
 170             if (outlen == 0)
 171                 break;
 172             out += mdlen;
 173         } else {
 174             if (!EVP_DigestFinal(&mctx, mtmp, NULL))
 175                 goto err;
 176             memcpy(out, mtmp, outlen);
 177             OPENSSL_cleanse(mtmp, mdlen);
 178             break;
 179         }
 180     }
 181     rv = 1;
 182  err:
 183     if (der)
 184         OPENSSL_free(der);
 185     EVP_MD_CTX_cleanup(&mctx);
 186     return rv;
 187 }