crypto/dh/dh_kdf.c

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