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openssl/crypto/ec/ec_ameth.c
Nicola Tuveri a377871db1 [PROV][KEYMGMT][EC] Import/export of priv_key as padded const time BN 
For EC keys it is particularly important to avoid leaking the bit length
of the secret scalar.

Key import/export should never leak the bit length of the secret
scalar in the key.

For this reason, on export we use padded BIGNUMs with fixed length,
using the new `ossl_param_bld_push_BN_pad()`.

When importing we also should make sure that, even if short lived,
the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as
soon as possible, so that any processing of this BIGNUM might opt for
constant time implementations in the backend.

Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have
to preallocate the BIGNUM internal buffer to a fixed size big enough
that operations performed during the processing never trigger a
realloc which would leak the size of the scalar through memory
accesses.

Fixed length
------------

The order of the large prime subgroup of the curve is our choice for
a fixed public size, as that is generally the upper bound for
generating a private key in EC cryptosystems and should fit all valid
secret scalars.

For padding on export we just use the bit length of the order
converted to bytes (rounding up).

For preallocating the BIGNUM storage we look at the number of "words"
required for the internal representation of the order, and we
preallocate 2 extra "words" in case any of the subsequent processing
might temporarily overflow the order length.

Future work
-----------

To ensure the flag and fixed size preallocation persists upon
`EC_KEY_set_private_key()`, we need to further harden
`EC_KEY_set_private_key()` and `BN_copy()`.
This is done in separate commits.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10631)
2020-02-18 19:11:10 +02:00

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/*
* Copyright 2006-2018 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
*/
/*
* ECDH and ECDSA low level APIs are deprecated for public use, but still ok
* for internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/x509.h>
#include <openssl/ec.h>
#include <openssl/bn.h>
#include <openssl/cms.h>
#include <openssl/asn1t.h>
#include "crypto/asn1.h"
#include "crypto/evp.h"
#include <openssl/core_names.h>
#include "internal/param_build.h"
#include "ec_local.h"
#ifndef OPENSSL_NO_CMS
static int ecdh_cms_decrypt(CMS_RecipientInfo *ri);
static int ecdh_cms_encrypt(CMS_RecipientInfo *ri);
#endif
static int eckey_param2type(int *pptype, void **ppval, const EC_KEY *ec_key)
{
const EC_GROUP *group;
int nid;
if (ec_key == NULL || (group = EC_KEY_get0_group(ec_key)) == NULL) {
ECerr(EC_F_ECKEY_PARAM2TYPE, EC_R_MISSING_PARAMETERS);
return 0;
}
if (EC_GROUP_get_asn1_flag(group)
&& (nid = EC_GROUP_get_curve_name(group)))
/* we have a 'named curve' => just set the OID */
{
*ppval = OBJ_nid2obj(nid);
*pptype = V_ASN1_OBJECT;
} else { /* explicit parameters */
ASN1_STRING *pstr = NULL;
pstr = ASN1_STRING_new();
if (pstr == NULL)
return 0;
pstr->length = i2d_ECParameters(ec_key, &pstr->data);
if (pstr->length <= 0) {
ASN1_STRING_free(pstr);
ECerr(EC_F_ECKEY_PARAM2TYPE, ERR_R_EC_LIB);
return 0;
}
*ppval = pstr;
*pptype = V_ASN1_SEQUENCE;
}
return 1;
}
static int eckey_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
{
const EC_KEY *ec_key = pkey->pkey.ec;
void *pval = NULL;
int ptype;
unsigned char *penc = NULL, *p;
int penclen;
if (!eckey_param2type(&ptype, &pval, ec_key)) {
ECerr(EC_F_ECKEY_PUB_ENCODE, ERR_R_EC_LIB);
return 0;
}
penclen = i2o_ECPublicKey(ec_key, NULL);
if (penclen <= 0)
goto err;
penc = OPENSSL_malloc(penclen);
if (penc == NULL)
goto err;
p = penc;
penclen = i2o_ECPublicKey(ec_key, &p);
if (penclen <= 0)
goto err;
if (X509_PUBKEY_set0_param(pk, OBJ_nid2obj(EVP_PKEY_EC),
ptype, pval, penc, penclen))
return 1;
err:
if (ptype == V_ASN1_OBJECT)
ASN1_OBJECT_free(pval);
else
ASN1_STRING_free(pval);
OPENSSL_free(penc);
return 0;
}
static EC_KEY *eckey_type2param(int ptype, const void *pval)
{
EC_KEY *eckey = NULL;
EC_GROUP *group = NULL;
if (ptype == V_ASN1_SEQUENCE) {
const ASN1_STRING *pstr = pval;
const unsigned char *pm = pstr->data;
int pmlen = pstr->length;
if ((eckey = d2i_ECParameters(NULL, &pm, pmlen)) == NULL) {
ECerr(EC_F_ECKEY_TYPE2PARAM, EC_R_DECODE_ERROR);
goto ecerr;
}
} else if (ptype == V_ASN1_OBJECT) {
const ASN1_OBJECT *poid = pval;
/*
* type == V_ASN1_OBJECT => the parameters are given by an asn1 OID
*/
if ((eckey = EC_KEY_new()) == NULL) {
ECerr(EC_F_ECKEY_TYPE2PARAM, ERR_R_MALLOC_FAILURE);
goto ecerr;
}
group = EC_GROUP_new_by_curve_name(OBJ_obj2nid(poid));
if (group == NULL)
goto ecerr;
EC_GROUP_set_asn1_flag(group, OPENSSL_EC_NAMED_CURVE);
if (EC_KEY_set_group(eckey, group) == 0)
goto ecerr;
EC_GROUP_free(group);
} else {
ECerr(EC_F_ECKEY_TYPE2PARAM, EC_R_DECODE_ERROR);
goto ecerr;
}
return eckey;
ecerr:
EC_KEY_free(eckey);
EC_GROUP_free(group);
return NULL;
}
static int eckey_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
{
const unsigned char *p = NULL;
const void *pval;
int ptype, pklen;
EC_KEY *eckey = NULL;
X509_ALGOR *palg;
if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
return 0;
X509_ALGOR_get0(NULL, &ptype, &pval, palg);
eckey = eckey_type2param(ptype, pval);
if (!eckey) {
ECerr(EC_F_ECKEY_PUB_DECODE, ERR_R_EC_LIB);
return 0;
}
/* We have parameters now set public key */
if (!o2i_ECPublicKey(&eckey, &p, pklen)) {
ECerr(EC_F_ECKEY_PUB_DECODE, EC_R_DECODE_ERROR);
goto ecerr;
}
EVP_PKEY_assign_EC_KEY(pkey, eckey);
return 1;
ecerr:
EC_KEY_free(eckey);
return 0;
}
static int eckey_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
{
int r;
const EC_GROUP *group = EC_KEY_get0_group(b->pkey.ec);
const EC_POINT *pa = EC_KEY_get0_public_key(a->pkey.ec),
*pb = EC_KEY_get0_public_key(b->pkey.ec);
if (group == NULL || pa == NULL || pb == NULL)
return -2;
r = EC_POINT_cmp(group, pa, pb, NULL);
if (r == 0)
return 1;
if (r == 1)
return 0;
return -2;
}
static int eckey_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
{
const unsigned char *p = NULL;
const void *pval;
int ptype, pklen;
EC_KEY *eckey = NULL;
const X509_ALGOR *palg;
if (!PKCS8_pkey_get0(NULL, &p, &pklen, &palg, p8))
return 0;
X509_ALGOR_get0(NULL, &ptype, &pval, palg);
eckey = eckey_type2param(ptype, pval);
if (eckey == NULL)
goto ecliberr;
/* We have parameters now set private key */
if (!d2i_ECPrivateKey(&eckey, &p, pklen)) {
ECerr(EC_F_ECKEY_PRIV_DECODE, EC_R_DECODE_ERROR);
goto ecerr;
}
EVP_PKEY_assign_EC_KEY(pkey, eckey);
return 1;
ecliberr:
ECerr(EC_F_ECKEY_PRIV_DECODE, ERR_R_EC_LIB);
ecerr:
EC_KEY_free(eckey);
return 0;
}
static int eckey_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
{
EC_KEY ec_key = *(pkey->pkey.ec);
unsigned char *ep, *p;
int eplen, ptype;
void *pval;
unsigned int old_flags;
if (!eckey_param2type(&ptype, &pval, &ec_key)) {
ECerr(EC_F_ECKEY_PRIV_ENCODE, EC_R_DECODE_ERROR);
return 0;
}
/* set the private key */
/*
* do not include the parameters in the SEC1 private key see PKCS#11
* 12.11
*/
old_flags = EC_KEY_get_enc_flags(&ec_key);
EC_KEY_set_enc_flags(&ec_key, old_flags | EC_PKEY_NO_PARAMETERS);
eplen = i2d_ECPrivateKey(&ec_key, NULL);
if (!eplen) {
ECerr(EC_F_ECKEY_PRIV_ENCODE, ERR_R_EC_LIB);
return 0;
}
ep = OPENSSL_malloc(eplen);
if (ep == NULL) {
ECerr(EC_F_ECKEY_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
return 0;
}
p = ep;
if (!i2d_ECPrivateKey(&ec_key, &p)) {
OPENSSL_free(ep);
ECerr(EC_F_ECKEY_PRIV_ENCODE, ERR_R_EC_LIB);
return 0;
}
if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(NID_X9_62_id_ecPublicKey), 0,
ptype, pval, ep, eplen)) {
OPENSSL_free(ep);
return 0;
}
return 1;
}
static int int_ec_size(const EVP_PKEY *pkey)
{
return ECDSA_size(pkey->pkey.ec);
}
static int ec_bits(const EVP_PKEY *pkey)
{
return EC_GROUP_order_bits(EC_KEY_get0_group(pkey->pkey.ec));
}
static int ec_security_bits(const EVP_PKEY *pkey)
{
int ecbits = ec_bits(pkey);
if (ecbits >= 512)
return 256;
if (ecbits >= 384)
return 192;
if (ecbits >= 256)
return 128;
if (ecbits >= 224)
return 112;
if (ecbits >= 160)
return 80;
return ecbits / 2;
}
static int ec_missing_parameters(const EVP_PKEY *pkey)
{
if (pkey->pkey.ec == NULL || EC_KEY_get0_group(pkey->pkey.ec) == NULL)
return 1;
return 0;
}
static int ec_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from)
{
EC_GROUP *group = EC_GROUP_dup(EC_KEY_get0_group(from->pkey.ec));
if (group == NULL)
return 0;
if (to->pkey.ec == NULL) {
to->pkey.ec = EC_KEY_new();
if (to->pkey.ec == NULL)
goto err;
}
if (EC_KEY_set_group(to->pkey.ec, group) == 0)
goto err;
EC_GROUP_free(group);
return 1;
err:
EC_GROUP_free(group);
return 0;
}
static int ec_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
{
const EC_GROUP *group_a = EC_KEY_get0_group(a->pkey.ec),
*group_b = EC_KEY_get0_group(b->pkey.ec);
if (group_a == NULL || group_b == NULL)
return -2;
if (EC_GROUP_cmp(group_a, group_b, NULL))
return 0;
else
return 1;
}
static void int_ec_free(EVP_PKEY *pkey)
{
EC_KEY_free(pkey->pkey.ec);
}
typedef enum {
EC_KEY_PRINT_PRIVATE,
EC_KEY_PRINT_PUBLIC,
EC_KEY_PRINT_PARAM
} ec_print_t;
static int do_EC_KEY_print(BIO *bp, const EC_KEY *x, int off, ec_print_t ktype)
{
const char *ecstr;
unsigned char *priv = NULL, *pub = NULL;
size_t privlen = 0, publen = 0;
int ret = 0;
const EC_GROUP *group;
if (x == NULL || (group = EC_KEY_get0_group(x)) == NULL) {
ECerr(EC_F_DO_EC_KEY_PRINT, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if (ktype != EC_KEY_PRINT_PARAM && EC_KEY_get0_public_key(x) != NULL) {
publen = EC_KEY_key2buf(x, EC_KEY_get_conv_form(x), &pub, NULL);
if (publen == 0)
goto err;
}
if (ktype == EC_KEY_PRINT_PRIVATE && EC_KEY_get0_private_key(x) != NULL) {
privlen = EC_KEY_priv2buf(x, &priv);
if (privlen == 0)
goto err;
}
if (ktype == EC_KEY_PRINT_PRIVATE)
ecstr = "Private-Key";
else if (ktype == EC_KEY_PRINT_PUBLIC)
ecstr = "Public-Key";
else
ecstr = "ECDSA-Parameters";
if (!BIO_indent(bp, off, 128))
goto err;
if (BIO_printf(bp, "%s: (%d bit)\n", ecstr,
EC_GROUP_order_bits(group)) <= 0)
goto err;
if (privlen != 0) {
if (BIO_printf(bp, "%*spriv:\n", off, "") <= 0)
goto err;
if (ASN1_buf_print(bp, priv, privlen, off + 4) == 0)
goto err;
}
if (publen != 0) {
if (BIO_printf(bp, "%*spub:\n", off, "") <= 0)
goto err;
if (ASN1_buf_print(bp, pub, publen, off + 4) == 0)
goto err;
}
if (!ECPKParameters_print(bp, group, off))
goto err;
ret = 1;
err:
if (!ret)
ECerr(EC_F_DO_EC_KEY_PRINT, ERR_R_EC_LIB);
OPENSSL_clear_free(priv, privlen);
OPENSSL_free(pub);
return ret;
}
static int eckey_param_decode(EVP_PKEY *pkey,
const unsigned char **pder, int derlen)
{
EC_KEY *eckey;
if ((eckey = d2i_ECParameters(NULL, pder, derlen)) == NULL) {
ECerr(EC_F_ECKEY_PARAM_DECODE, ERR_R_EC_LIB);
return 0;
}
EVP_PKEY_assign_EC_KEY(pkey, eckey);
return 1;
}
static int eckey_param_encode(const EVP_PKEY *pkey, unsigned char **pder)
{
return i2d_ECParameters(pkey->pkey.ec, pder);
}
static int eckey_param_print(BIO *bp, const EVP_PKEY *pkey, int indent,
ASN1_PCTX *ctx)
{
return do_EC_KEY_print(bp, pkey->pkey.ec, indent, EC_KEY_PRINT_PARAM);
}
static int eckey_pub_print(BIO *bp, const EVP_PKEY *pkey, int indent,
ASN1_PCTX *ctx)
{
return do_EC_KEY_print(bp, pkey->pkey.ec, indent, EC_KEY_PRINT_PUBLIC);
}
static int eckey_priv_print(BIO *bp, const EVP_PKEY *pkey, int indent,
ASN1_PCTX *ctx)
{
return do_EC_KEY_print(bp, pkey->pkey.ec, indent, EC_KEY_PRINT_PRIVATE);
}
static int old_ec_priv_decode(EVP_PKEY *pkey,
const unsigned char **pder, int derlen)
{
EC_KEY *ec;
if ((ec = d2i_ECPrivateKey(NULL, pder, derlen)) == NULL) {
ECerr(EC_F_OLD_EC_PRIV_DECODE, EC_R_DECODE_ERROR);
return 0;
}
EVP_PKEY_assign_EC_KEY(pkey, ec);
return 1;
}
static int old_ec_priv_encode(const EVP_PKEY *pkey, unsigned char **pder)
{
return i2d_ECPrivateKey(pkey->pkey.ec, pder);
}
static int ec_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
{
switch (op) {
case ASN1_PKEY_CTRL_PKCS7_SIGN:
if (arg1 == 0) {
int snid, hnid;
X509_ALGOR *alg1, *alg2;
PKCS7_SIGNER_INFO_get0_algs(arg2, NULL, &alg1, &alg2);
if (alg1 == NULL || alg1->algorithm == NULL)
return -1;
hnid = OBJ_obj2nid(alg1->algorithm);
if (hnid == NID_undef)
return -1;
if (!OBJ_find_sigid_by_algs(&snid, hnid, EVP_PKEY_id(pkey)))
return -1;
X509_ALGOR_set0(alg2, OBJ_nid2obj(snid), V_ASN1_UNDEF, 0);
}
return 1;
#ifndef OPENSSL_NO_CMS
case ASN1_PKEY_CTRL_CMS_SIGN:
if (arg1 == 0) {
int snid, hnid;
X509_ALGOR *alg1, *alg2;
CMS_SignerInfo_get0_algs(arg2, NULL, NULL, &alg1, &alg2);
if (alg1 == NULL || alg1->algorithm == NULL)
return -1;
hnid = OBJ_obj2nid(alg1->algorithm);
if (hnid == NID_undef)
return -1;
if (!OBJ_find_sigid_by_algs(&snid, hnid, EVP_PKEY_id(pkey)))
return -1;
X509_ALGOR_set0(alg2, OBJ_nid2obj(snid), V_ASN1_UNDEF, 0);
}
return 1;
case ASN1_PKEY_CTRL_CMS_ENVELOPE:
if (arg1 == 1)
return ecdh_cms_decrypt(arg2);
else if (arg1 == 0)
return ecdh_cms_encrypt(arg2);
return -2;
case ASN1_PKEY_CTRL_CMS_RI_TYPE:
*(int *)arg2 = CMS_RECIPINFO_AGREE;
return 1;
#endif
case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
if (EVP_PKEY_id(pkey) == EVP_PKEY_SM2) {
/* For SM2, the only valid digest-alg is SM3 */
*(int *)arg2 = NID_sm3;
return 2; /* Make it mandatory */
}
*(int *)arg2 = NID_sha256;
return 1;
case ASN1_PKEY_CTRL_SET1_TLS_ENCPT:
return EC_KEY_oct2key(EVP_PKEY_get0_EC_KEY(pkey), arg2, arg1, NULL);
case ASN1_PKEY_CTRL_GET1_TLS_ENCPT:
return EC_KEY_key2buf(EVP_PKEY_get0_EC_KEY(pkey),
POINT_CONVERSION_UNCOMPRESSED, arg2, NULL);
default:
return -2;
}
}
static int ec_pkey_check(const EVP_PKEY *pkey)
{
EC_KEY *eckey = pkey->pkey.ec;
/* stay consistent to what EVP_PKEY_check demands */
if (eckey->priv_key == NULL) {
ECerr(EC_F_EC_PKEY_CHECK, EC_R_MISSING_PRIVATE_KEY);
return 0;
}
return EC_KEY_check_key(eckey);
}
static int ec_pkey_public_check(const EVP_PKEY *pkey)
{
EC_KEY *eckey = pkey->pkey.ec;
/*
* Note: it unnecessary to check eckey->pub_key here since
* it will be checked in EC_KEY_check_key(). In fact, the
* EC_KEY_check_key() mainly checks the public key, and checks
* the private key optionally (only if there is one). So if
* someone passes a whole EC key (public + private), this
* will also work...
*/
return EC_KEY_check_key(eckey);
}
static int ec_pkey_param_check(const EVP_PKEY *pkey)
{
EC_KEY *eckey = pkey->pkey.ec;
/* stay consistent to what EVP_PKEY_check demands */
if (eckey->group == NULL) {
ECerr(EC_F_EC_PKEY_PARAM_CHECK, EC_R_MISSING_PARAMETERS);
return 0;
}
return EC_GROUP_check(eckey->group, NULL);
}
static
size_t ec_pkey_dirty_cnt(const EVP_PKEY *pkey)
{
return pkey->pkey.ec->dirty_cnt;
}
static ossl_inline
int ecparams_to_params(const EC_KEY *eckey, OSSL_PARAM_BLD *tmpl)
{
const EC_GROUP *ecg;
int curve_nid;
if (eckey == NULL)
return 0;
ecg = EC_KEY_get0_group(eckey);
if (ecg == NULL)
return 0;
curve_nid = EC_GROUP_get_curve_name(ecg);
if (curve_nid == NID_undef) {
/* explicit parameters */
/*
* TODO(3.0): should we support explicit parameters curves?
*/
return 0;
} else {
/* named curve */
const char *curve_name = NULL;
if ((curve_name = OBJ_nid2sn(curve_nid)) == NULL)
return 0;
if (!ossl_param_bld_push_utf8_string(tmpl, OSSL_PKEY_PARAM_EC_NAME, curve_name, 0))
return 0;
}
return 1;
}
static
int ec_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
EVP_KEYMGMT *to_keymgmt)
{
const EC_KEY *eckey = NULL;
const EC_GROUP *ecg = NULL;
unsigned char *pub_key_buf = NULL;
size_t pub_key_buflen;
OSSL_PARAM_BLD tmpl;
OSSL_PARAM *params = NULL;
const BIGNUM *priv_key = NULL;
const EC_POINT *pub_point = NULL;
int rv = 0;
if (from == NULL
|| (eckey = from->pkey.ec) == NULL
|| (ecg = EC_KEY_get0_group(eckey)) == NULL)
return 0;
ossl_param_bld_init(&tmpl);
/* export the domain parameters */
if (!ecparams_to_params(eckey, &tmpl))
return 0;
priv_key = EC_KEY_get0_private_key(eckey);
pub_point = EC_KEY_get0_public_key(eckey);
/* public_key must be present, priv_key is optional */
if (pub_point == NULL)
return 0;
/* convert pub_point to a octet string according to the SECG standard */
if ((pub_key_buflen = EC_POINT_point2buf(ecg, pub_point,
POINT_CONVERSION_COMPRESSED,
&pub_key_buf, NULL)) == 0)
return 0;
if (!ossl_param_bld_push_octet_string(&tmpl,
OSSL_PKEY_PARAM_PUB_KEY,
pub_key_buf,
pub_key_buflen))
goto err;
if (priv_key != NULL) {
size_t sz;
int ecbits;
int ecdh_cofactor_mode;
/*
* Key import/export should never leak the bit length of the secret
* scalar in the key.
*
* For this reason, on export we use padded BIGNUMs with fixed length.
*
* When importing we also should make sure that, even if short lived,
* the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as
* soon as possible, so that any processing of this BIGNUM might opt for
* constant time implementations in the backend.
*
* Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have
* to preallocate the BIGNUM internal buffer to a fixed public size big
* enough that operations performed during the processing never trigger
* a realloc which would leak the size of the scalar through memory
* accesses.
*
* Fixed Length
* ------------
*
* The order of the large prime subgroup of the curve is our choice for
* a fixed public size, as that is generally the upper bound for
* generating a private key in EC cryptosystems and should fit all valid
* secret scalars.
*
* For padding on export we just use the bit length of the order
* converted to bytes (rounding up).
*
* For preallocating the BIGNUM storage we look at the number of "words"
* required for the internal representation of the order, and we
* preallocate 2 extra "words" in case any of the subsequent processing
* might temporarily overflow the order length.
*/
ecbits = EC_GROUP_order_bits(ecg);
if (ecbits <= 0)
goto err;
sz = (ecbits + 7 ) / 8;
if (!ossl_param_bld_push_BN_pad(&tmpl,
OSSL_PKEY_PARAM_PRIV_KEY,
priv_key, sz))
goto err;
/*
* The ECDH Cofactor Mode is defined only if the EC_KEY actually
* contains a private key, so we check for the flag and export it only
* in this case.
*/
ecdh_cofactor_mode =
(EC_KEY_get_flags(eckey) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
/* Export the ECDH_COFACTOR_MODE parameter */
if (!ossl_param_bld_push_int(&tmpl,
OSSL_PKEY_PARAM_USE_COFACTOR_ECDH,
ecdh_cofactor_mode))
goto err;
}
params = ossl_param_bld_to_param(&tmpl);
/* We export, the provider imports */
rv = evp_keymgmt_import(to_keymgmt, to_keydata, OSSL_KEYMGMT_SELECT_ALL,
params);
err:
ossl_param_bld_free(params);
OPENSSL_free(pub_key_buf);
return rv;
}
const EVP_PKEY_ASN1_METHOD eckey_asn1_meth = {
EVP_PKEY_EC,
EVP_PKEY_EC,
0,
"EC",
"OpenSSL EC algorithm",
eckey_pub_decode,
eckey_pub_encode,
eckey_pub_cmp,
eckey_pub_print,
eckey_priv_decode,
eckey_priv_encode,
eckey_priv_print,
int_ec_size,
ec_bits,
ec_security_bits,
eckey_param_decode,
eckey_param_encode,
ec_missing_parameters,
ec_copy_parameters,
ec_cmp_parameters,
eckey_param_print,
0,
int_ec_free,
ec_pkey_ctrl,
old_ec_priv_decode,
old_ec_priv_encode,
0, 0, 0,
ec_pkey_check,
ec_pkey_public_check,
ec_pkey_param_check,
0, /* set_priv_key */
0, /* set_pub_key */
0, /* get_priv_key */
0, /* get_pub_key */
ec_pkey_dirty_cnt,
ec_pkey_export_to
};
#if !defined(OPENSSL_NO_SM2)
const EVP_PKEY_ASN1_METHOD sm2_asn1_meth = {
EVP_PKEY_SM2,
EVP_PKEY_EC,
ASN1_PKEY_ALIAS
};
#endif
int EC_KEY_print(BIO *bp, const EC_KEY *x, int off)
{
int private = EC_KEY_get0_private_key(x) != NULL;
return do_EC_KEY_print(bp, x, off,
private ? EC_KEY_PRINT_PRIVATE : EC_KEY_PRINT_PUBLIC);
}
int ECParameters_print(BIO *bp, const EC_KEY *x)
{
return do_EC_KEY_print(bp, x, 4, EC_KEY_PRINT_PARAM);
}
#ifndef OPENSSL_NO_CMS
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;
EC_KEY *ecpeer = 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) {
const EC_GROUP *grp;
EVP_PKEY *pk;
pk = EVP_PKEY_CTX_get0_pkey(pctx);
if (pk == NULL)
goto err;
grp = EC_KEY_get0_group(pk->pkey.ec);
ecpeer = EC_KEY_new();
if (ecpeer == NULL)
goto err;
if (!EC_KEY_set_group(ecpeer, grp))
goto err;
} else {
ecpeer = eckey_type2param(atype, aval);
if (!ecpeer)
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;
if (!o2i_ECPublicKey(&ecpeer, &p, plen))
goto err;
pkpeer = EVP_PKEY_new();
if (pkpeer == NULL)
goto err;
EVP_PKEY_set1_EC_KEY(pkpeer, ecpeer);
if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
rv = 1;
err:
EC_KEY_free(ecpeer);
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;
const EVP_CIPHER *kekcipher;
EVP_CIPHER_CTX *kekctx;
if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
return 0;
if (!ecdh_cms_set_kdf_param(pctx, OBJ_obj2nid(alg->algorithm))) {
ECerr(EC_F_ECDH_CMS_SET_SHARED_INFO, EC_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)
goto err;
kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
if (!kekctx)
goto err;
kekcipher = EVP_get_cipherbyobj(kekalg->algorithm);
if (!kekcipher || 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)
goto err;
if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, der, plen) <= 0)
goto err;
der = NULL;
rv = 1;
err:
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)
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)) {
ECerr(EC_F_ECDH_CMS_DECRYPT, EC_R_PEER_KEY_ERROR);
return 0;
}
}
/* Set ECDH derivation parameters and initialise unwrap context */
if (!ecdh_cms_set_shared_info(pctx, ri)) {
ECerr(EC_F_ECDH_CMS_DECRYPT, EC_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;
int 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)
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)) {
EC_KEY *eckey = pkey->pkey.ec;
/* Set the key */
unsigned char *p;
penclen = i2o_ECPublicKey(eckey, NULL);
if (penclen <= 0)
goto err;
penc = OPENSSL_malloc(penclen);
if (penc == NULL)
goto err;
p = penc;
penclen = i2o_ECPublicKey(eckey, &p);
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_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;
}
#endif
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