+/*
+ * Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (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 <openssl/cms.h>
+#include <openssl/err.h>
+#include <openssl/decoder.h>
+#include "cms_local.h"
+#include "crypto/evp.h"
+
+
+static EVP_PKEY *pkey_type2param(int ptype, const void *pval,
+ OPENSSL_CTX *libctx, const char *propq)
+{
+ EVP_PKEY *pkey = NULL;
+ EVP_PKEY_CTX *pctx = NULL;
+
+ if (ptype == V_ASN1_SEQUENCE) {
+ const ASN1_STRING *pstr = pval;
+ const unsigned char *pm = pstr->data;
+ int pmlen = pstr->length;
+ OSSL_DECODER_CTX *ctx = NULL;
+ BIO *membio = NULL;
+
+ /* TODO(3.0): Need to be able to specify here that only params will do */
+ ctx = OSSL_DECODER_CTX_new_by_EVP_PKEY(&pkey, "DER", "EC", libctx,
+ propq);
+ membio = BIO_new_mem_buf(pm, pmlen);
+ OSSL_DECODER_from_bio(ctx, membio);
+ BIO_free(membio);
+ OSSL_DECODER_CTX_free(ctx);
+ } else if (ptype == V_ASN1_OBJECT) {
+ const ASN1_OBJECT *poid = pval;
+ const char *groupname;
+
+ /*
+ * type == V_ASN1_OBJECT => the parameters are given by an asn1 OID
+ */
+
+ pctx = EVP_PKEY_CTX_new_from_name(libctx, "EC", propq);
+
+ if (pctx == NULL)
+ goto err;
+ if (EVP_PKEY_paramgen_init(pctx) <= 0)
+ goto err;
+ groupname = OBJ_nid2sn(OBJ_obj2nid(poid));
+ if (groupname == NULL
+ || !EVP_PKEY_CTX_set_group_name(pctx, groupname)) {
+ CMSerr(0, CMS_R_DECODE_ERROR);
+ goto err;
+ }
+ if (EVP_PKEY_paramgen(pctx, &pkey) <= 0) {
+ EVP_PKEY_free(pkey);
+ pkey = NULL;
+ }
+ } else {
+ CMSerr(0, CMS_R_DECODE_ERROR);
+ goto err;
+ }
+
+ return pkey;
+
+ err:
+ EVP_PKEY_free(pkey);
+ EVP_PKEY_CTX_free(pctx);
+ return NULL;
+}
+
+static int ecdh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
+ X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
+{
+ const ASN1_OBJECT *aoid;
+ int atype;
+ const void *aval;
+ int rv = 0;
+ EVP_PKEY *pkpeer = NULL;
+ const unsigned char *p;
+ int plen;
+
+ X509_ALGOR_get0(&aoid, &atype, &aval, alg);
+ if (OBJ_obj2nid(aoid) != NID_X9_62_id_ecPublicKey)
+ goto err;
+ /* If absent parameters get group from main key */
+ if (atype == V_ASN1_UNDEF || atype == V_ASN1_NULL) {
+ EVP_PKEY *pk;
+ pk = EVP_PKEY_CTX_get0_pkey(pctx);
+ if (pk == NULL)
+ goto err;
+
+ pkpeer = EVP_PKEY_new();
+ if (pkpeer == NULL)
+ goto err;
+ if (!EVP_PKEY_copy_parameters(pkpeer, pk))
+ goto err;
+ } else {
+ /* TODO(3.0): Should the get0_libctx/propq calls actually be public API? */
+ pkpeer = pkey_type2param(atype, aval,
+ evp_pkey_ctx_get0_libctx(pctx),
+ evp_pkey_ctx_get0_propq(pctx));
+ if (pkpeer == NULL)
+ goto err;
+ }
+ /* We have parameters now set public key */
+ plen = ASN1_STRING_length(pubkey);
+ p = ASN1_STRING_get0_data(pubkey);
+ if (p == NULL || plen == 0)
+ goto err;
+
+ /* TODO(3.0): Terrible name. We need a non-tls specific name */
+ if (!EVP_PKEY_set1_tls_encodedpoint(pkpeer, p, plen))
+ goto err;
+
+ if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
+ rv = 1;
+ err:
+ EVP_PKEY_free(pkpeer);
+ return rv;
+}
+
+/* Set KDF parameters based on KDF NID */
+static int ecdh_cms_set_kdf_param(EVP_PKEY_CTX *pctx, int eckdf_nid)
+{
+ int kdf_nid, kdfmd_nid, cofactor;
+ const EVP_MD *kdf_md;
+ if (eckdf_nid == NID_undef)
+ return 0;
+
+ /* Lookup KDF type, cofactor mode and digest */
+ if (!OBJ_find_sigid_algs(eckdf_nid, &kdfmd_nid, &kdf_nid))
+ return 0;
+
+ if (kdf_nid == NID_dh_std_kdf)
+ cofactor = 0;
+ else if (kdf_nid == NID_dh_cofactor_kdf)
+ cofactor = 1;
+ else
+ return 0;
+
+ if (EVP_PKEY_CTX_set_ecdh_cofactor_mode(pctx, cofactor) <= 0)
+ return 0;
+
+ if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, EVP_PKEY_ECDH_KDF_X9_63) <= 0)
+ return 0;
+
+ kdf_md = EVP_get_digestbynid(kdfmd_nid);
+ if (!kdf_md)
+ return 0;
+
+ if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
+ return 0;
+ return 1;
+}
+
+static int ecdh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
+{
+ int rv = 0;
+
+ X509_ALGOR *alg, *kekalg = NULL;
+ ASN1_OCTET_STRING *ukm;
+ const unsigned char *p;
+ unsigned char *der = NULL;
+ int plen, keylen;
+ EVP_CIPHER *kekcipher = NULL;
+ EVP_CIPHER_CTX *kekctx;
+ const char *name;
+
+ if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
+ return 0;
+
+ if (!ecdh_cms_set_kdf_param(pctx, OBJ_obj2nid(alg->algorithm))) {
+ CMSerr(0, CMS_R_KDF_PARAMETER_ERROR);
+ return 0;
+ }
+
+ if (alg->parameter->type != V_ASN1_SEQUENCE)
+ return 0;
+
+ p = alg->parameter->value.sequence->data;
+ plen = alg->parameter->value.sequence->length;
+ kekalg = d2i_X509_ALGOR(NULL, &p, plen);
+ if (kekalg == NULL)
+ goto err;
+ kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
+ if (kekctx == NULL)
+ goto err;
+ name = OBJ_nid2sn(OBJ_obj2nid(kekalg->algorithm));
+ kekcipher = EVP_CIPHER_fetch(pctx->libctx, name, pctx->propquery);
+ if (kekcipher == NULL || EVP_CIPHER_mode(kekcipher) != EVP_CIPH_WRAP_MODE)
+ goto err;
+ if (!EVP_EncryptInit_ex(kekctx, kekcipher, NULL, NULL, NULL))
+ goto err;
+ if (EVP_CIPHER_asn1_to_param(kekctx, kekalg->parameter) <= 0)
+ goto err;
+
+ keylen = EVP_CIPHER_CTX_key_length(kekctx);
+ if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
+ goto err;
+
+ plen = CMS_SharedInfo_encode(&der, kekalg, ukm, keylen);
+
+ if (plen <= 0)
+ goto err;
+
+ if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, der, plen) <= 0)
+ goto err;
+ der = NULL;
+
+ rv = 1;
+ err:
+ EVP_CIPHER_free(kekcipher);
+ X509_ALGOR_free(kekalg);
+ OPENSSL_free(der);
+ return rv;
+}
+
+static int ecdh_cms_decrypt(CMS_RecipientInfo *ri)
+{
+ EVP_PKEY_CTX *pctx;
+
+ pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
+ if (pctx == NULL)
+ return 0;
+ /* See if we need to set peer key */
+ if (!EVP_PKEY_CTX_get0_peerkey(pctx)) {
+ X509_ALGOR *alg;
+ ASN1_BIT_STRING *pubkey;
+
+ if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &alg, &pubkey,
+ NULL, NULL, NULL))
+ return 0;
+ if (!alg || !pubkey)
+ return 0;
+ if (!ecdh_cms_set_peerkey(pctx, alg, pubkey)) {
+ CMSerr(0, CMS_R_PEER_KEY_ERROR);
+ return 0;
+ }
+ }
+ /* Set ECDH derivation parameters and initialise unwrap context */
+ if (!ecdh_cms_set_shared_info(pctx, ri)) {
+ CMSerr(0, CMS_R_SHARED_INFO_ERROR);
+ return 0;
+ }
+ return 1;
+}
+
+static int ecdh_cms_encrypt(CMS_RecipientInfo *ri)
+{
+ EVP_PKEY_CTX *pctx;
+ EVP_PKEY *pkey;
+ EVP_CIPHER_CTX *ctx;
+ int keylen;
+ X509_ALGOR *talg, *wrap_alg = NULL;
+ const ASN1_OBJECT *aoid;
+ ASN1_BIT_STRING *pubkey;
+ ASN1_STRING *wrap_str;
+ ASN1_OCTET_STRING *ukm;
+ unsigned char *penc = NULL;
+ size_t penclen;
+ int rv = 0;
+ int ecdh_nid, kdf_type, kdf_nid, wrap_nid;
+ const EVP_MD *kdf_md;
+
+ pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
+ if (pctx == NULL)
+ return 0;
+ /* Get ephemeral key */
+ pkey = EVP_PKEY_CTX_get0_pkey(pctx);
+ if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &talg, &pubkey,
+ NULL, NULL, NULL))
+ goto err;
+ X509_ALGOR_get0(&aoid, NULL, NULL, talg);
+ /* Is everything uninitialised? */
+ if (aoid == OBJ_nid2obj(NID_undef)) {
+ /* Set the key */
+
+ /* TODO(3.0): Terrible name. Needs a non TLS specific name */
+ penclen = EVP_PKEY_get1_tls_encodedpoint(pkey, &penc);
+ ASN1_STRING_set0(pubkey, penc, penclen);
+ pubkey->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);
+ pubkey->flags |= ASN1_STRING_FLAG_BITS_LEFT;
+
+ penc = NULL;
+ X509_ALGOR_set0(talg, OBJ_nid2obj(NID_X9_62_id_ecPublicKey),
+ V_ASN1_UNDEF, NULL);
+ }
+
+ /* See if custom parameters set */
+ kdf_type = EVP_PKEY_CTX_get_ecdh_kdf_type(pctx);
+ if (kdf_type <= 0)
+ goto err;
+ if (!EVP_PKEY_CTX_get_ecdh_kdf_md(pctx, &kdf_md))
+ goto err;
+ ecdh_nid = EVP_PKEY_CTX_get_ecdh_cofactor_mode(pctx);
+ if (ecdh_nid < 0)
+ goto err;
+ else if (ecdh_nid == 0)
+ ecdh_nid = NID_dh_std_kdf;
+ else if (ecdh_nid == 1)
+ ecdh_nid = NID_dh_cofactor_kdf;
+
+ if (kdf_type == EVP_PKEY_ECDH_KDF_NONE) {
+ kdf_type = EVP_PKEY_ECDH_KDF_X9_63;
+ if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, kdf_type) <= 0)
+ goto err;
+ } else
+ /* Unknown KDF */
+ goto err;
+ if (kdf_md == NULL) {
+ /* Fixme later for better MD */
+ kdf_md = EVP_sha1();
+ if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
+ goto err;
+ }
+
+ if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
+ goto err;
+
+ /* Lookup NID for KDF+cofactor+digest */
+
+ if (!OBJ_find_sigid_by_algs(&kdf_nid, EVP_MD_type(kdf_md), ecdh_nid))
+ goto err;
+ /* Get wrap NID */
+ ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
+ wrap_nid = EVP_CIPHER_CTX_type(ctx);
+ keylen = EVP_CIPHER_CTX_key_length(ctx);
+
+ /* Package wrap algorithm in an AlgorithmIdentifier */
+
+ wrap_alg = X509_ALGOR_new();
+ if (wrap_alg == NULL)
+ goto err;
+ wrap_alg->algorithm = OBJ_nid2obj(wrap_nid);
+ wrap_alg->parameter = ASN1_TYPE_new();
+ if (wrap_alg->parameter == NULL)
+ goto err;
+ if (EVP_CIPHER_param_to_asn1(ctx, wrap_alg->parameter) <= 0)
+ goto err;
+ if (ASN1_TYPE_get(wrap_alg->parameter) == NID_undef) {
+ ASN1_TYPE_free(wrap_alg->parameter);
+ wrap_alg->parameter = NULL;
+ }
+
+ if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
+ goto err;
+
+ penclen = CMS_SharedInfo_encode(&penc, wrap_alg, ukm, keylen);
+
+ if (!penclen)
+ goto err;
+
+ if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, penc, penclen) <= 0)
+ goto err;
+ penc = NULL;
+
+ /*
+ * Now need to wrap encoding of wrap AlgorithmIdentifier into parameter
+ * of another AlgorithmIdentifier.
+ */
+ penclen = i2d_X509_ALGOR(wrap_alg, &penc);
+ if (!penc || !penclen)
+ goto err;
+ wrap_str = ASN1_STRING_new();
+ if (wrap_str == NULL)
+ goto err;
+ ASN1_STRING_set0(wrap_str, penc, penclen);
+ penc = NULL;
+ X509_ALGOR_set0(talg, OBJ_nid2obj(kdf_nid), V_ASN1_SEQUENCE, wrap_str);
+
+ rv = 1;
+
+ err:
+ OPENSSL_free(penc);
+ X509_ALGOR_free(wrap_alg);
+ return rv;
+}
+
+int cms_ecdh_envelope(CMS_RecipientInfo *ri, int decrypt)
+{
+ if (decrypt == 1)
+ return ecdh_cms_decrypt(ri);
+ else if (decrypt == 0)
+ return ecdh_cms_encrypt(ri);
+
+ CMSerr(0, CMS_R_NOT_SUPPORTED_FOR_THIS_KEY_TYPE);
+ return 0;
+}
\ No newline at end of file