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