ref: 009439541d2c6e8af2596f8fb1b4df85861fd212
dir: /third_party/boringssl/src/crypto/ec_extra/ec_asn1.c/
/* Written by Nils Larsch for the OpenSSL project. */
/* ====================================================================
* Copyright (c) 2000-2003 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* licensing@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/ec.h>
#include <limits.h>
#include <string.h>
#include <openssl/bytestring.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/nid.h>
#include "../fipsmodule/ec/internal.h"
#include "../bytestring/internal.h"
#include "../internal.h"
static const CBS_ASN1_TAG kParametersTag =
CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 0;
static const CBS_ASN1_TAG kPublicKeyTag =
CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 1;
// TODO(https://crbug.com/boringssl/497): Allow parsers to specify a list of
// acceptable groups, so parsers don't have to pull in all four.
typedef const EC_GROUP *(*ec_group_func)(void);
static const ec_group_func kAllGroups[] = {
&EC_group_p224,
&EC_group_p256,
&EC_group_p384,
&EC_group_p521,
};
EC_KEY *EC_KEY_parse_private_key(CBS *cbs, const EC_GROUP *group) {
CBS ec_private_key, private_key;
uint64_t version;
if (!CBS_get_asn1(cbs, &ec_private_key, CBS_ASN1_SEQUENCE) ||
!CBS_get_asn1_uint64(&ec_private_key, &version) ||
version != 1 ||
!CBS_get_asn1(&ec_private_key, &private_key, CBS_ASN1_OCTETSTRING)) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
return NULL;
}
// Parse the optional parameters field.
EC_KEY *ret = NULL;
BIGNUM *priv_key = NULL;
if (CBS_peek_asn1_tag(&ec_private_key, kParametersTag)) {
// Per SEC 1, as an alternative to omitting it, one is allowed to specify
// this field and put in a NULL to mean inheriting this value. This was
// omitted in a previous version of this logic without problems, so leave it
// unimplemented.
CBS child;
if (!CBS_get_asn1(&ec_private_key, &child, kParametersTag)) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
goto err;
}
const EC_GROUP *inner_group = EC_KEY_parse_parameters(&child);
if (inner_group == NULL) {
goto err;
}
if (group == NULL) {
group = inner_group;
} else if (EC_GROUP_cmp(group, inner_group, NULL) != 0) {
// If a group was supplied externally, it must match.
OPENSSL_PUT_ERROR(EC, EC_R_GROUP_MISMATCH);
goto err;
}
if (CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
goto err;
}
}
if (group == NULL) {
OPENSSL_PUT_ERROR(EC, EC_R_MISSING_PARAMETERS);
goto err;
}
ret = EC_KEY_new();
if (ret == NULL || !EC_KEY_set_group(ret, group)) {
goto err;
}
// Although RFC 5915 specifies the length of the key, OpenSSL historically
// got this wrong, so accept any length. See upstream's
// 30cd4ff294252c4b6a4b69cbef6a5b4117705d22.
priv_key = BN_bin2bn(CBS_data(&private_key), CBS_len(&private_key), NULL);
ret->pub_key = EC_POINT_new(group);
if (priv_key == NULL || ret->pub_key == NULL ||
!EC_KEY_set_private_key(ret, priv_key)) {
goto err;
}
if (CBS_peek_asn1_tag(&ec_private_key, kPublicKeyTag)) {
CBS child, public_key;
uint8_t padding;
if (!CBS_get_asn1(&ec_private_key, &child, kPublicKeyTag) ||
!CBS_get_asn1(&child, &public_key, CBS_ASN1_BITSTRING) ||
// As in a SubjectPublicKeyInfo, the byte-encoded public key is then
// encoded as a BIT STRING with bits ordered as in the DER encoding.
!CBS_get_u8(&public_key, &padding) ||
padding != 0 ||
// Explicitly check |public_key| is non-empty to save the conversion
// form later.
CBS_len(&public_key) == 0 ||
!EC_POINT_oct2point(group, ret->pub_key, CBS_data(&public_key),
CBS_len(&public_key), NULL) ||
CBS_len(&child) != 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
goto err;
}
// Save the point conversion form.
// TODO(davidben): Consider removing this.
ret->conv_form =
(point_conversion_form_t)(CBS_data(&public_key)[0] & ~0x01);
} else {
// Compute the public key instead.
if (!ec_point_mul_scalar_base(group, &ret->pub_key->raw,
&ret->priv_key->scalar)) {
goto err;
}
// Remember the original private-key-only encoding.
// TODO(davidben): Consider removing this.
ret->enc_flag |= EC_PKEY_NO_PUBKEY;
}
if (CBS_len(&ec_private_key) != 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
goto err;
}
// Ensure the resulting key is valid.
if (!EC_KEY_check_key(ret)) {
goto err;
}
BN_free(priv_key);
return ret;
err:
EC_KEY_free(ret);
BN_free(priv_key);
return NULL;
}
int EC_KEY_marshal_private_key(CBB *cbb, const EC_KEY *key,
unsigned enc_flags) {
if (key == NULL || key->group == NULL || key->priv_key == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
CBB ec_private_key, private_key;
if (!CBB_add_asn1(cbb, &ec_private_key, CBS_ASN1_SEQUENCE) ||
!CBB_add_asn1_uint64(&ec_private_key, 1 /* version */) ||
!CBB_add_asn1(&ec_private_key, &private_key, CBS_ASN1_OCTETSTRING) ||
!BN_bn2cbb_padded(&private_key,
BN_num_bytes(EC_GROUP_get0_order(key->group)),
EC_KEY_get0_private_key(key))) {
OPENSSL_PUT_ERROR(EC, EC_R_ENCODE_ERROR);
return 0;
}
if (!(enc_flags & EC_PKEY_NO_PARAMETERS)) {
CBB child;
if (!CBB_add_asn1(&ec_private_key, &child, kParametersTag) ||
!EC_KEY_marshal_curve_name(&child, key->group) ||
!CBB_flush(&ec_private_key)) {
OPENSSL_PUT_ERROR(EC, EC_R_ENCODE_ERROR);
return 0;
}
}
// TODO(fork): replace this flexibility with sensible default?
if (!(enc_flags & EC_PKEY_NO_PUBKEY) && key->pub_key != NULL) {
CBB child, public_key;
if (!CBB_add_asn1(&ec_private_key, &child, kPublicKeyTag) ||
!CBB_add_asn1(&child, &public_key, CBS_ASN1_BITSTRING) ||
// As in a SubjectPublicKeyInfo, the byte-encoded public key is then
// encoded as a BIT STRING with bits ordered as in the DER encoding.
!CBB_add_u8(&public_key, 0 /* padding */) ||
!EC_POINT_point2cbb(&public_key, key->group, key->pub_key,
key->conv_form, NULL) ||
!CBB_flush(&ec_private_key)) {
OPENSSL_PUT_ERROR(EC, EC_R_ENCODE_ERROR);
return 0;
}
}
if (!CBB_flush(cbb)) {
OPENSSL_PUT_ERROR(EC, EC_R_ENCODE_ERROR);
return 0;
}
return 1;
}
// kPrimeFieldOID is the encoding of 1.2.840.10045.1.1.
static const uint8_t kPrimeField[] = {0x2a, 0x86, 0x48, 0xce, 0x3d, 0x01, 0x01};
struct explicit_prime_curve {
CBS prime, a, b, base_x, base_y, order;
};
static int parse_explicit_prime_curve(CBS *in,
struct explicit_prime_curve *out) {
// See RFC 3279, section 2.3.5. Note that RFC 3279 calls this structure an
// ECParameters while RFC 5480 calls it a SpecifiedECDomain.
CBS params, field_id, field_type, curve, base, cofactor;
int has_cofactor;
uint64_t version;
if (!CBS_get_asn1(in, ¶ms, CBS_ASN1_SEQUENCE) ||
!CBS_get_asn1_uint64(¶ms, &version) ||
version != 1 ||
!CBS_get_asn1(¶ms, &field_id, CBS_ASN1_SEQUENCE) ||
!CBS_get_asn1(&field_id, &field_type, CBS_ASN1_OBJECT) ||
CBS_len(&field_type) != sizeof(kPrimeField) ||
OPENSSL_memcmp(CBS_data(&field_type), kPrimeField, sizeof(kPrimeField)) !=
0 ||
!CBS_get_asn1(&field_id, &out->prime, CBS_ASN1_INTEGER) ||
!CBS_is_unsigned_asn1_integer(&out->prime) ||
CBS_len(&field_id) != 0 ||
!CBS_get_asn1(¶ms, &curve, CBS_ASN1_SEQUENCE) ||
!CBS_get_asn1(&curve, &out->a, CBS_ASN1_OCTETSTRING) ||
!CBS_get_asn1(&curve, &out->b, CBS_ASN1_OCTETSTRING) ||
// |curve| has an optional BIT STRING seed which we ignore.
!CBS_get_optional_asn1(&curve, NULL, NULL, CBS_ASN1_BITSTRING) ||
CBS_len(&curve) != 0 ||
!CBS_get_asn1(¶ms, &base, CBS_ASN1_OCTETSTRING) ||
!CBS_get_asn1(¶ms, &out->order, CBS_ASN1_INTEGER) ||
!CBS_is_unsigned_asn1_integer(&out->order) ||
!CBS_get_optional_asn1(¶ms, &cofactor, &has_cofactor,
CBS_ASN1_INTEGER) ||
CBS_len(¶ms) != 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
return 0;
}
if (has_cofactor) {
// We only support prime-order curves so the cofactor must be one.
if (CBS_len(&cofactor) != 1 ||
CBS_data(&cofactor)[0] != 1) {
OPENSSL_PUT_ERROR(EC, EC_R_UNKNOWN_GROUP);
return 0;
}
}
// Require that the base point use uncompressed form.
uint8_t form;
if (!CBS_get_u8(&base, &form) || form != POINT_CONVERSION_UNCOMPRESSED) {
OPENSSL_PUT_ERROR(EC, EC_R_INVALID_FORM);
return 0;
}
if (CBS_len(&base) % 2 != 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
return 0;
}
size_t field_len = CBS_len(&base) / 2;
CBS_init(&out->base_x, CBS_data(&base), field_len);
CBS_init(&out->base_y, CBS_data(&base) + field_len, field_len);
return 1;
}
// integers_equal returns one if |bytes| is a big-endian encoding of |bn|, and
// zero otherwise.
static int integers_equal(const CBS *bytes, const BIGNUM *bn) {
// Although, in SEC 1, Field-Element-to-Octet-String has a fixed width,
// OpenSSL mis-encodes the |a| and |b|, so we tolerate any number of leading
// zeros. (This matters for P-521 whose |b| has a leading 0.)
CBS copy = *bytes;
while (CBS_len(©) > 0 && CBS_data(©)[0] == 0) {
CBS_skip(©, 1);
}
if (CBS_len(©) > EC_MAX_BYTES) {
return 0;
}
uint8_t buf[EC_MAX_BYTES];
if (!BN_bn2bin_padded(buf, CBS_len(©), bn)) {
ERR_clear_error();
return 0;
}
return CBS_mem_equal(©, buf, CBS_len(©));
}
EC_GROUP *EC_KEY_parse_curve_name(CBS *cbs) {
CBS named_curve;
if (!CBS_get_asn1(cbs, &named_curve, CBS_ASN1_OBJECT)) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
return NULL;
}
// Look for a matching curve.
for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kAllGroups); i++) {
const EC_GROUP *group = kAllGroups[i]();
if (CBS_mem_equal(&named_curve, group->oid, group->oid_len)) {
return (EC_GROUP *)group;
}
}
OPENSSL_PUT_ERROR(EC, EC_R_UNKNOWN_GROUP);
return NULL;
}
int EC_KEY_marshal_curve_name(CBB *cbb, const EC_GROUP *group) {
if (group->oid_len == 0) {
OPENSSL_PUT_ERROR(EC, EC_R_UNKNOWN_GROUP);
return 0;
}
CBB child;
return CBB_add_asn1(cbb, &child, CBS_ASN1_OBJECT) &&
CBB_add_bytes(&child, group->oid, group->oid_len) && //
CBB_flush(cbb);
}
EC_GROUP *EC_KEY_parse_parameters(CBS *cbs) {
if (!CBS_peek_asn1_tag(cbs, CBS_ASN1_SEQUENCE)) {
return EC_KEY_parse_curve_name(cbs);
}
// OpenSSL sometimes produces ECPrivateKeys with explicitly-encoded versions
// of named curves.
//
// TODO(davidben): Remove support for this.
struct explicit_prime_curve curve;
if (!parse_explicit_prime_curve(cbs, &curve)) {
return NULL;
}
const EC_GROUP *ret = NULL;
BIGNUM *p = BN_new(), *a = BN_new(), *b = BN_new(), *x = BN_new(),
*y = BN_new();
if (p == NULL || a == NULL || b == NULL || x == NULL || y == NULL) {
goto err;
}
for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kAllGroups); i++) {
const EC_GROUP *group = kAllGroups[i]();
if (!integers_equal(&curve.order, EC_GROUP_get0_order(group))) {
continue;
}
// The order alone uniquely identifies the group, but we check the other
// parameters to avoid misinterpreting the group.
if (!EC_GROUP_get_curve_GFp(group, p, a, b, NULL)) {
goto err;
}
if (!integers_equal(&curve.prime, p) || !integers_equal(&curve.a, a) ||
!integers_equal(&curve.b, b)) {
break;
}
if (!EC_POINT_get_affine_coordinates_GFp(
group, EC_GROUP_get0_generator(group), x, y, NULL)) {
goto err;
}
if (!integers_equal(&curve.base_x, x) ||
!integers_equal(&curve.base_y, y)) {
break;
}
ret = group;
break;
}
if (ret == NULL) {
OPENSSL_PUT_ERROR(EC, EC_R_UNKNOWN_GROUP);
}
err:
BN_free(p);
BN_free(a);
BN_free(b);
BN_free(x);
BN_free(y);
return (EC_GROUP *)ret;
}
int EC_POINT_point2cbb(CBB *out, const EC_GROUP *group, const EC_POINT *point,
point_conversion_form_t form, BN_CTX *ctx) {
size_t len = EC_POINT_point2oct(group, point, form, NULL, 0, ctx);
if (len == 0) {
return 0;
}
uint8_t *p;
return CBB_add_space(out, &p, len) &&
EC_POINT_point2oct(group, point, form, p, len, ctx) == len;
}
EC_KEY *d2i_ECPrivateKey(EC_KEY **out, const uint8_t **inp, long len) {
// This function treats its |out| parameter differently from other |d2i|
// functions. If supplied, take the group from |*out|.
const EC_GROUP *group = NULL;
if (out != NULL && *out != NULL) {
group = EC_KEY_get0_group(*out);
}
if (len < 0) {
OPENSSL_PUT_ERROR(EC, EC_R_DECODE_ERROR);
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
EC_KEY *ret = EC_KEY_parse_private_key(&cbs, group);
if (ret == NULL) {
return NULL;
}
if (out != NULL) {
EC_KEY_free(*out);
*out = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_ECPrivateKey(const EC_KEY *key, uint8_t **outp) {
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!EC_KEY_marshal_private_key(&cbb, key, EC_KEY_get_enc_flags(key))) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}
EC_KEY *d2i_ECParameters(EC_KEY **out_key, const uint8_t **inp, long len) {
if (len < 0) {
return NULL;
}
CBS cbs;
CBS_init(&cbs, *inp, (size_t)len);
const EC_GROUP *group = EC_KEY_parse_parameters(&cbs);
if (group == NULL) {
return NULL;
}
EC_KEY *ret = EC_KEY_new();
if (ret == NULL || !EC_KEY_set_group(ret, group)) {
EC_KEY_free(ret);
return NULL;
}
if (out_key != NULL) {
EC_KEY_free(*out_key);
*out_key = ret;
}
*inp = CBS_data(&cbs);
return ret;
}
int i2d_ECParameters(const EC_KEY *key, uint8_t **outp) {
if (key == NULL || key->group == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
return -1;
}
CBB cbb;
if (!CBB_init(&cbb, 0) ||
!EC_KEY_marshal_curve_name(&cbb, key->group)) {
CBB_cleanup(&cbb);
return -1;
}
return CBB_finish_i2d(&cbb, outp);
}
EC_KEY *o2i_ECPublicKey(EC_KEY **keyp, const uint8_t **inp, long len) {
EC_KEY *ret = NULL;
if (keyp == NULL || *keyp == NULL || (*keyp)->group == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
ret = *keyp;
if (ret->pub_key == NULL &&
(ret->pub_key = EC_POINT_new(ret->group)) == NULL) {
return NULL;
}
if (!EC_POINT_oct2point(ret->group, ret->pub_key, *inp, len, NULL)) {
OPENSSL_PUT_ERROR(EC, ERR_R_EC_LIB);
return NULL;
}
// save the point conversion form
ret->conv_form = (point_conversion_form_t)(*inp[0] & ~0x01);
*inp += len;
return ret;
}
int i2o_ECPublicKey(const EC_KEY *key, uint8_t **outp) {
if (key == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
CBB cbb;
if (!CBB_init(&cbb, 0) || //
!EC_POINT_point2cbb(&cbb, key->group, key->pub_key, key->conv_form,
NULL)) {
CBB_cleanup(&cbb);
return -1;
}
int ret = CBB_finish_i2d(&cbb, outp);
// Historically, this function used the wrong return value on error.
return ret > 0 ? ret : 0;
}
size_t EC_get_builtin_curves(EC_builtin_curve *out_curves,
size_t max_num_curves) {
if (max_num_curves > OPENSSL_ARRAY_SIZE(kAllGroups)) {
max_num_curves = OPENSSL_ARRAY_SIZE(kAllGroups);
}
for (size_t i = 0; i < max_num_curves; i++) {
const EC_GROUP *group = kAllGroups[i]();
out_curves[i].nid = group->curve_name;
out_curves[i].comment = group->comment;
}
return OPENSSL_ARRAY_SIZE(kAllGroups);
}