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