1 /* 2 * Copyright 2013-2016 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include "e_os.h" 11 12 #ifndef OPENSSL_NO_CMS 13 #include <string.h> 14 #include <openssl/dh.h> 15 #include <openssl/evp.h> 16 #include <openssl/asn1.h> 17 #include <openssl/cms.h> 18 19 20 /* Key derivation from X9.42/RFC2631 */ 21 /* Uses CMS functions, hence the #ifdef wrapper. */ 22 23 #define DH_KDF_MAX (1L << 30) 24 25 /* Skip past an ASN1 structure: for OBJECT skip content octets too */ 26 27 static int skip_asn1(unsigned char **pp, long *plen, int exptag) 28 { 29 const unsigned char *q = *pp; 30 int i, tag, xclass; 31 long tmplen; 32 i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen); 33 if (i & 0x80) 34 return 0; 35 if (tag != exptag || xclass != V_ASN1_UNIVERSAL) 36 return 0; 37 if (tag == V_ASN1_OBJECT) 38 q += tmplen; 39 *plen -= q - *pp; 40 *pp = (unsigned char *)q; 41 return 1; 42 } 43 44 /* 45 * Encode the DH shared info structure, return an offset to the counter value 46 * so we can update the structure without reencoding it. 47 */ 48 49 static int dh_sharedinfo_encode(unsigned char **pder, unsigned char **pctr, 50 ASN1_OBJECT *key_oid, size_t outlen, 51 const unsigned char *ukm, size_t ukmlen) 52 { 53 unsigned char *p; 54 int derlen; 55 long tlen; 56 /* "magic" value to check offset is sane */ 57 static unsigned char ctr[4] = { 0xF3, 0x17, 0x22, 0x53 }; 58 X509_ALGOR atmp; 59 ASN1_OCTET_STRING ctr_oct, ukm_oct, *pukm_oct; 60 ASN1_TYPE ctr_atype; 61 if (ukmlen > DH_KDF_MAX || outlen > DH_KDF_MAX) 62 return 0; 63 ctr_oct.data = ctr; 64 ctr_oct.length = 4; 65 ctr_oct.flags = 0; 66 ctr_oct.type = V_ASN1_OCTET_STRING; 67 ctr_atype.type = V_ASN1_OCTET_STRING; 68 ctr_atype.value.octet_string = &ctr_oct; 69 atmp.algorithm = key_oid; 70 atmp.parameter = &ctr_atype; 71 if (ukm) { 72 ukm_oct.type = V_ASN1_OCTET_STRING; 73 ukm_oct.flags = 0; 74 ukm_oct.data = (unsigned char *)ukm; 75 ukm_oct.length = ukmlen; 76 pukm_oct = &ukm_oct; 77 } else 78 pukm_oct = NULL; 79 derlen = CMS_SharedInfo_encode(pder, &atmp, pukm_oct, outlen); 80 if (derlen <= 0) 81 return 0; 82 p = *pder; 83 tlen = derlen; 84 if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE)) 85 return 0; 86 if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE)) 87 return 0; 88 if (!skip_asn1(&p, &tlen, V_ASN1_OBJECT)) 89 return 0; 90 if (!skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING)) 91 return 0; 92 if (CRYPTO_memcmp(p, ctr, 4)) 93 return 0; 94 *pctr = p; 95 return derlen; 96 } 97 98 int DH_KDF_X9_42(unsigned char *out, size_t outlen, 99 const unsigned char *Z, size_t Zlen, 100 ASN1_OBJECT *key_oid, 101 const unsigned char *ukm, size_t ukmlen, const EVP_MD *md) 102 { 103 EVP_MD_CTX *mctx = NULL; 104 int rv = 0; 105 unsigned int i; 106 size_t mdlen; 107 unsigned char *der = NULL, *ctr; 108 int derlen; 109 if (Zlen > DH_KDF_MAX) 110 return 0; 111 mctx = EVP_MD_CTX_new(); 112 if (mctx == NULL) 113 return 0; 114 mdlen = EVP_MD_size(md); 115 derlen = dh_sharedinfo_encode(&der, &ctr, key_oid, outlen, ukm, ukmlen); 116 if (derlen == 0) 117 goto err; 118 for (i = 1;; i++) { 119 unsigned char mtmp[EVP_MAX_MD_SIZE]; 120 if (!EVP_DigestInit_ex(mctx, md, NULL) 121 || !EVP_DigestUpdate(mctx, Z, Zlen)) 122 goto err; 123 ctr[3] = i & 0xFF; 124 ctr[2] = (i >> 8) & 0xFF; 125 ctr[1] = (i >> 16) & 0xFF; 126 ctr[0] = (i >> 24) & 0xFF; 127 if (!EVP_DigestUpdate(mctx, der, derlen)) 128 goto err; 129 if (outlen >= mdlen) { 130 if (!EVP_DigestFinal(mctx, out, NULL)) 131 goto err; 132 outlen -= mdlen; 133 if (outlen == 0) 134 break; 135 out += mdlen; 136 } else { 137 if (!EVP_DigestFinal(mctx, mtmp, NULL)) 138 goto err; 139 memcpy(out, mtmp, outlen); 140 OPENSSL_cleanse(mtmp, mdlen); 141 break; 142 } 143 } 144 rv = 1; 145 err: 146 OPENSSL_free(der); 147 EVP_MD_CTX_free(mctx); 148 return rv; 149 } 150 #endif 151