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/*
* Copyright 2006-2023 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 <assert.h>
#include <openssl/cms.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/core_names.h>
#include "internal/sizes.h"
#include "crypto/evp.h"
#include "cms_local.h"
static int dh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
{
const ASN1_OBJECT *aoid;
int atype;
const void *aval;
ASN1_INTEGER *public_key = NULL;
int rv = 0;
EVP_PKEY *pkpeer = NULL, *pk = NULL;
BIGNUM *bnpub = NULL;
const unsigned char *p;
unsigned char *buf = NULL;
int plen;
X509_ALGOR_get0(&aoid, &atype, &aval, alg);
if (OBJ_obj2nid(aoid) != NID_dhpublicnumber)
goto err;
/* Only absent parameters allowed in RFC XXXX */
if (atype != V_ASN1_UNDEF && atype == V_ASN1_NULL)
goto err;
pk = EVP_PKEY_CTX_get0_pkey(pctx);
if (pk == NULL || !EVP_PKEY_is_a(pk, "DHX"))
goto err;
/* Get public key */
plen = ASN1_STRING_length(pubkey);
p = ASN1_STRING_get0_data(pubkey);
if (p == NULL || plen == 0)
goto err;
if ((public_key = d2i_ASN1_INTEGER(NULL, &p, plen)) == NULL)
goto err;
/*
* Pad to full p parameter size as that is checked by
* EVP_PKEY_set1_encoded_public_key()
*/
plen = EVP_PKEY_get_size(pk);
if ((bnpub = ASN1_INTEGER_to_BN(public_key, NULL)) == NULL)
goto err;
if ((buf = OPENSSL_malloc(plen)) == NULL)
goto err;
if (BN_bn2binpad(bnpub, buf, plen) < 0)
goto err;
pkpeer = EVP_PKEY_new();
if (pkpeer == NULL
|| !EVP_PKEY_copy_parameters(pkpeer, pk)
|| !EVP_PKEY_set1_encoded_public_key(pkpeer, buf, plen))
goto err;
if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
rv = 1;
err:
ASN1_INTEGER_free(public_key);
BN_free(bnpub);
OPENSSL_free(buf);
EVP_PKEY_free(pkpeer);
return rv;
}
static int dh_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 *dukm = NULL;
size_t dukmlen = 0;
int keylen, plen;
EVP_CIPHER *kekcipher = NULL;
EVP_CIPHER_CTX *kekctx;
char name[OSSL_MAX_NAME_SIZE];
if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
goto err;
/*
* For DH we only have one OID permissible. If ever any more get defined
* we will need something cleverer.
*/
if (OBJ_obj2nid(alg->algorithm) != NID_id_smime_alg_ESDH) {
ERR_raise(ERR_LIB_CMS, CMS_R_KDF_PARAMETER_ERROR);
goto err;
}
if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, EVP_PKEY_DH_KDF_X9_42) <= 0
|| EVP_PKEY_CTX_set_dh_kdf_md(pctx, EVP_sha1()) <= 0)
goto err;
if (alg->parameter->type != V_ASN1_SEQUENCE)
goto err;
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;
if (OBJ_obj2txt(name, sizeof(name), kekalg->algorithm, 0) <= 0)
goto err;
kekcipher = EVP_CIPHER_fetch(pctx->libctx, name, pctx->propquery);
if (kekcipher == NULL
|| EVP_CIPHER_get_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_get_key_length(kekctx);
if (EVP_PKEY_CTX_set_dh_kdf_outlen(pctx, keylen) <= 0)
goto err;
/* Use OBJ_nid2obj to ensure we use built in OID that isn't freed */
if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx,
OBJ_nid2obj(EVP_CIPHER_get_type(kekcipher)))
<= 0)
goto err;
if (ukm != NULL) {
dukmlen = ASN1_STRING_length(ukm);
dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
if (dukm == NULL)
goto err;
}
if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
goto err;
dukm = NULL;
rv = 1;
err:
X509_ALGOR_free(kekalg);
EVP_CIPHER_free(kekcipher);
OPENSSL_free(dukm);
return rv;
}
static int dh_cms_decrypt(CMS_RecipientInfo *ri)
{
EVP_PKEY_CTX *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 == NULL || pubkey == NULL)
return 0;
if (!dh_cms_set_peerkey(pctx, alg, pubkey)) {
ERR_raise(ERR_LIB_CMS, CMS_R_PEER_KEY_ERROR);
return 0;
}
}
/* Set DH derivation parameters and initialise unwrap context */
if (!dh_cms_set_shared_info(pctx, ri)) {
ERR_raise(ERR_LIB_CMS, CMS_R_SHARED_INFO_ERROR);
return 0;
}
return 1;
}
static int dh_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, *dukm = NULL;
int penclen;
size_t dukmlen = 0;
int rv = 0;
int kdf_type, 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;
/* Is everything uninitialised? */
X509_ALGOR_get0(&aoid, NULL, NULL, talg);
if (aoid == OBJ_nid2obj(NID_undef)) {
BIGNUM *bn_pub_key = NULL;
ASN1_INTEGER *pubk;
if (!EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_PUB_KEY, &bn_pub_key))
goto err;
pubk = BN_to_ASN1_INTEGER(bn_pub_key, NULL);
BN_free(bn_pub_key);
if (pubk == NULL)
goto err;
/* Set the key */
penclen = i2d_ASN1_INTEGER(pubk, &penc);
ASN1_INTEGER_free(pubk);
if (penclen <= 0)
goto err;
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_dhpublicnumber),
V_ASN1_UNDEF, NULL);
}
/* See if custom parameters set */
kdf_type = EVP_PKEY_CTX_get_dh_kdf_type(pctx);
if (kdf_type <= 0 || EVP_PKEY_CTX_get_dh_kdf_md(pctx, &kdf_md) <= 0)
goto err;
if (kdf_type == EVP_PKEY_DH_KDF_NONE) {
kdf_type = EVP_PKEY_DH_KDF_X9_42;
if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, kdf_type) <= 0)
goto err;
} else if (kdf_type != EVP_PKEY_DH_KDF_X9_42)
/* Unknown KDF */
goto err;
if (kdf_md == NULL) {
/* Only SHA1 supported */
kdf_md = EVP_sha1();
if (EVP_PKEY_CTX_set_dh_kdf_md(pctx, kdf_md) <= 0)
goto err;
} else if (EVP_MD_get_type(kdf_md) != NID_sha1)
/* Unsupported digest */
goto err;
if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
goto err;
/* Get wrap NID */
ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
wrap_nid = EVP_CIPHER_CTX_get_type(ctx);
if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx, OBJ_nid2obj(wrap_nid)) <= 0)
goto err;
keylen = EVP_CIPHER_CTX_get_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_dh_kdf_outlen(pctx, keylen) <= 0)
goto err;
if (ukm != NULL) {
dukmlen = ASN1_STRING_length(ukm);
dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
if (dukm == NULL)
goto err;
}
if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
goto err;
dukm = NULL;
/*
* Now need to wrap encoding of wrap AlgorithmIdentifier into parameter
* of another AlgorithmIdentifier.
*/
penc = NULL;
penclen = i2d_X509_ALGOR(wrap_alg, &penc);
if (penclen <= 0)
goto err;
wrap_str = ASN1_STRING_new();
if (wrap_str == NULL)
goto err;
ASN1_STRING_set0(wrap_str, penc, penclen);
penc = NULL;
rv = X509_ALGOR_set0(talg, OBJ_nid2obj(NID_id_smime_alg_ESDH),
V_ASN1_SEQUENCE, wrap_str);
if (!rv)
ASN1_STRING_free(wrap_str);
err:
OPENSSL_free(penc);
X509_ALGOR_free(wrap_alg);
OPENSSL_free(dukm);
return rv;
}
int ossl_cms_dh_envelope(CMS_RecipientInfo *ri, int decrypt)
{
assert(decrypt == 0 || decrypt == 1);
if (decrypt == 1)
return dh_cms_decrypt(ri);
if (decrypt == 0)
return dh_cms_encrypt(ri);
ERR_raise(ERR_LIB_CMS, CMS_R_NOT_SUPPORTED_FOR_THIS_KEY_TYPE);
return 0;
}
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