151 lines
4.2 KiB
C
151 lines
4.2 KiB
C
/*
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* Copyright 2013-2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "e_os.h"
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#ifndef OPENSSL_NO_CMS
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#include <string.h>
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#include <openssl/dh.h>
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#include <openssl/evp.h>
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#include <openssl/asn1.h>
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#include <openssl/cms.h>
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/* Key derivation from X9.42/RFC2631 */
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/* Uses CMS functions, hence the #ifdef wrapper. */
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#define DH_KDF_MAX (1L << 30)
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/* Skip past an ASN1 structure: for OBJECT skip content octets too */
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static int skip_asn1(unsigned char **pp, long *plen, int exptag)
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{
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const unsigned char *q = *pp;
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int i, tag, xclass;
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long tmplen;
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i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen);
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if (i & 0x80)
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return 0;
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if (tag != exptag || xclass != V_ASN1_UNIVERSAL)
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return 0;
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if (tag == V_ASN1_OBJECT)
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q += tmplen;
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*plen -= q - *pp;
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*pp = (unsigned char *)q;
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return 1;
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}
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/*
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* Encode the DH shared info structure, return an offset to the counter value
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* so we can update the structure without reencoding it.
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*/
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static int dh_sharedinfo_encode(unsigned char **pder, unsigned char **pctr,
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ASN1_OBJECT *key_oid, size_t outlen,
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const unsigned char *ukm, size_t ukmlen)
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{
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unsigned char *p;
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int derlen;
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long tlen;
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/* "magic" value to check offset is sane */
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static unsigned char ctr[4] = { 0xF3, 0x17, 0x22, 0x53 };
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X509_ALGOR atmp;
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ASN1_OCTET_STRING ctr_oct, ukm_oct, *pukm_oct;
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ASN1_TYPE ctr_atype;
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if (ukmlen > DH_KDF_MAX || outlen > DH_KDF_MAX)
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return 0;
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ctr_oct.data = ctr;
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ctr_oct.length = 4;
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ctr_oct.flags = 0;
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ctr_oct.type = V_ASN1_OCTET_STRING;
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ctr_atype.type = V_ASN1_OCTET_STRING;
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ctr_atype.value.octet_string = &ctr_oct;
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atmp.algorithm = key_oid;
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atmp.parameter = &ctr_atype;
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if (ukm) {
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ukm_oct.type = V_ASN1_OCTET_STRING;
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ukm_oct.flags = 0;
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ukm_oct.data = (unsigned char *)ukm;
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ukm_oct.length = ukmlen;
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pukm_oct = &ukm_oct;
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} else
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pukm_oct = NULL;
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derlen = CMS_SharedInfo_encode(pder, &atmp, pukm_oct, outlen);
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if (derlen <= 0)
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return 0;
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p = *pder;
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tlen = derlen;
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if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
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return 0;
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if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
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return 0;
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if (!skip_asn1(&p, &tlen, V_ASN1_OBJECT))
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return 0;
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if (!skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING))
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return 0;
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if (CRYPTO_memcmp(p, ctr, 4))
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return 0;
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*pctr = p;
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return derlen;
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}
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int DH_KDF_X9_42(unsigned char *out, size_t outlen,
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const unsigned char *Z, size_t Zlen,
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ASN1_OBJECT *key_oid,
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const unsigned char *ukm, size_t ukmlen, const EVP_MD *md)
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{
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EVP_MD_CTX *mctx = NULL;
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int rv = 0;
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unsigned int i;
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size_t mdlen;
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unsigned char *der = NULL, *ctr;
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int derlen;
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if (Zlen > DH_KDF_MAX)
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return 0;
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mctx = EVP_MD_CTX_new();
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if (mctx == NULL)
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return 0;
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mdlen = EVP_MD_size(md);
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derlen = dh_sharedinfo_encode(&der, &ctr, key_oid, outlen, ukm, ukmlen);
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if (derlen == 0)
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goto err;
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for (i = 1;; i++) {
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unsigned char mtmp[EVP_MAX_MD_SIZE];
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if (!EVP_DigestInit_ex(mctx, md, NULL)
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|| !EVP_DigestUpdate(mctx, Z, Zlen))
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goto err;
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ctr[3] = i & 0xFF;
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ctr[2] = (i >> 8) & 0xFF;
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ctr[1] = (i >> 16) & 0xFF;
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ctr[0] = (i >> 24) & 0xFF;
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if (!EVP_DigestUpdate(mctx, der, derlen))
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goto err;
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if (outlen >= mdlen) {
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if (!EVP_DigestFinal(mctx, out, NULL))
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goto err;
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outlen -= mdlen;
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if (outlen == 0)
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break;
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out += mdlen;
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} else {
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if (!EVP_DigestFinal(mctx, mtmp, NULL))
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goto err;
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memcpy(out, mtmp, outlen);
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OPENSSL_cleanse(mtmp, mdlen);
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break;
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}
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}
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rv = 1;
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err:
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OPENSSL_free(der);
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EVP_MD_CTX_free(mctx);
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return rv;
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}
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#endif
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