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openssl/crypto/ec/ecdsa_ossl.c
JohnnySavages 16311dbf53 Check EC_GROUP_get0_order result before dereference 
CLA: trivial

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24755)
2024-07-01 10:03:38 +02:00

549 lines
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/*
* Copyright 2002-2023 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
*/
/*
* ECDSA low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <string.h>
#include <openssl/err.h>
#include <openssl/obj_mac.h>
#include <openssl/rand.h>
#include "crypto/bn.h"
#include "ec_local.h"
#include "internal/deterministic_nonce.h"
#define MIN_ECDSA_SIGN_ORDERBITS 64
/*
* It is highly unlikely that a retry will happen,
* Multiple retries would indicate that something is wrong
* with the group parameters (which would normally only happen
* with a bad custom group).
*/
#define MAX_ECDSA_SIGN_RETRIES 8
static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
BIGNUM **kinvp, BIGNUM **rp,
const unsigned char *dgst, int dlen,
unsigned int nonce_type, const char *digestname,
OSSL_LIB_CTX *libctx, const char *propq);
int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
BIGNUM **rp)
{
if (eckey->group->meth->ecdsa_sign_setup == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
return 0;
}
return eckey->group->meth->ecdsa_sign_setup(eckey, ctx_in, kinvp, rp);
}
ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
const BIGNUM *in_kinv, const BIGNUM *in_r,
EC_KEY *eckey)
{
if (eckey->group->meth->ecdsa_sign_sig == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
return NULL;
}
return eckey->group->meth->ecdsa_sign_sig(dgst, dgst_len,
in_kinv, in_r, eckey);
}
int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
const ECDSA_SIG *sig, EC_KEY *eckey)
{
if (eckey->group->meth->ecdsa_verify_sig == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDSA);
return 0;
}
return eckey->group->meth->ecdsa_verify_sig(dgst, dgst_len, sig, eckey);
}
int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
unsigned char *sig, unsigned int *siglen,
const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
{
ECDSA_SIG *s;
if (sig == NULL && (kinv == NULL || r == NULL)) {
*siglen = ECDSA_size(eckey);
return 1;
}
s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
if (s == NULL) {
*siglen = 0;
return 0;
}
*siglen = i2d_ECDSA_SIG(s, sig != NULL ? &sig : NULL);
ECDSA_SIG_free(s);
return 1;
}
int ossl_ecdsa_deterministic_sign(const unsigned char *dgst, int dlen,
unsigned char *sig, unsigned int *siglen,
EC_KEY *eckey, unsigned int nonce_type,
const char *digestname,
OSSL_LIB_CTX *libctx, const char *propq)
{
ECDSA_SIG *s;
BIGNUM *kinv = NULL, *r = NULL;
int ret = 0;
if (sig == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
*siglen = 0;
if (!ecdsa_sign_setup(eckey, NULL, &kinv, &r, dgst, dlen,
nonce_type, digestname, libctx, propq))
return 0;
s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
if (s == NULL)
goto end;
*siglen = i2d_ECDSA_SIG(s, &sig);
ECDSA_SIG_free(s);
ret = 1;
end:
BN_clear_free(kinv);
BN_clear_free(r);
return ret;
}
static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
BIGNUM **kinvp, BIGNUM **rp,
const unsigned char *dgst, int dlen,
unsigned int nonce_type, const char *digestname,
OSSL_LIB_CTX *libctx, const char *propq)
{
BN_CTX *ctx = NULL;
BIGNUM *k = NULL, *r = NULL, *X = NULL;
const BIGNUM *order;
EC_POINT *tmp_point = NULL;
const EC_GROUP *group;
int ret = 0;
int order_bits;
const BIGNUM *priv_key;
if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
return 0;
}
if ((priv_key = EC_KEY_get0_private_key(eckey)) == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
return 0;
}
if (!EC_KEY_can_sign(eckey)) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
return 0;
}
if ((ctx = ctx_in) == NULL) {
if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
return 0;
}
}
k = BN_secure_new(); /* this value is later returned in *kinvp */
r = BN_new(); /* this value is later returned in *rp */
X = BN_new();
if (k == NULL || r == NULL || X == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
if ((tmp_point = EC_POINT_new(group)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if ((order = EC_GROUP_get0_order(group)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
/* Preallocate space */
order_bits = BN_num_bits(order);
/* Check the number of bits here so that an infinite loop is not possible */
if (order_bits < MIN_ECDSA_SIGN_ORDERBITS
|| !BN_set_bit(k, order_bits)
|| !BN_set_bit(r, order_bits)
|| !BN_set_bit(X, order_bits))
goto err;
do {
/* get random or deterministic value of k */
do {
int res = 0;
if (dgst != NULL) {
if (nonce_type == 1) {
#ifndef FIPS_MODULE
res = ossl_gen_deterministic_nonce_rfc6979(k, order,
priv_key,
dgst, dlen,
digestname,
libctx, propq);
#endif
} else {
res = ossl_bn_gen_dsa_nonce_fixed_top(k, order, priv_key,
dgst, dlen, ctx);
}
} else {
res = ossl_bn_priv_rand_range_fixed_top(k, order, 0, ctx);
}
if (!res) {
ERR_raise(ERR_LIB_EC, EC_R_RANDOM_NUMBER_GENERATION_FAILED);
goto err;
}
} while (ossl_bn_is_word_fixed_top(k, 0));
/* compute r the x-coordinate of generator * k */
if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_get_affine_coordinates(group, tmp_point, X, NULL, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (!BN_nnmod(r, X, order, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
} while (BN_is_zero(r));
/* compute the inverse of k */
if (!ossl_ec_group_do_inverse_ord(group, k, k, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* clear old values if necessary */
BN_clear_free(*rp);
BN_clear_free(*kinvp);
/* save the pre-computed values */
*rp = r;
*kinvp = k;
ret = 1;
err:
if (!ret) {
BN_clear_free(k);
BN_clear_free(r);
}
if (ctx != ctx_in)
BN_CTX_free(ctx);
EC_POINT_free(tmp_point);
BN_clear_free(X);
return ret;
}
int ossl_ecdsa_simple_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
BIGNUM **rp)
{
return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0,
0, NULL, NULL, NULL);
}
ECDSA_SIG *ossl_ecdsa_simple_sign_sig(const unsigned char *dgst, int dgst_len,
const BIGNUM *in_kinv, const BIGNUM *in_r,
EC_KEY *eckey)
{
int ok = 0, i;
int retries = 0;
BIGNUM *kinv = NULL, *s, *m = NULL;
const BIGNUM *order, *ckinv;
BN_CTX *ctx = NULL;
const EC_GROUP *group;
ECDSA_SIG *ret;
const BIGNUM *priv_key;
group = EC_KEY_get0_group(eckey);
priv_key = EC_KEY_get0_private_key(eckey);
if (group == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_PASSED_NULL_PARAMETER);
return NULL;
}
if (priv_key == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
return NULL;
}
if (!EC_KEY_can_sign(eckey)) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
return NULL;
}
ret = ECDSA_SIG_new();
if (ret == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_ECDSA_LIB);
return NULL;
}
ret->r = BN_new();
ret->s = BN_new();
if (ret->r == NULL || ret->s == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
s = ret->s;
if ((ctx = BN_CTX_new_ex(eckey->libctx)) == NULL
|| (m = BN_new()) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
if ((order = EC_GROUP_get0_order(group)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
i = BN_num_bits(order);
/*
* Need to truncate digest if it is too long: first truncate whole bytes.
*/
if (8 * dgst_len > i)
dgst_len = (i + 7) / 8;
if (!BN_bin2bn(dgst, dgst_len, m)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* If still too long, truncate remaining bits with a shift */
if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
do {
if (in_kinv == NULL || in_r == NULL) {
if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len,
0, NULL, NULL, NULL)) {
ERR_raise(ERR_LIB_EC, ERR_R_ECDSA_LIB);
goto err;
}
ckinv = kinv;
} else {
ckinv = in_kinv;
if (BN_copy(ret->r, in_r) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
}
/*
* With only one multiplicant being in Montgomery domain
* multiplication yields real result without post-conversion.
* Also note that all operations but last are performed with
* zero-padded vectors. Last operation, BN_mod_mul_montgomery
* below, returns user-visible value with removed zero padding.
*/
if (!bn_to_mont_fixed_top(s, ret->r, group->mont_data, ctx)
|| !bn_mul_mont_fixed_top(s, s, priv_key, group->mont_data, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
if (!bn_mod_add_fixed_top(s, s, m, order)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/*
* |s| can still be larger than modulus, because |m| can be. In
* such case we count on Montgomery reduction to tie it up.
*/
if (!bn_to_mont_fixed_top(s, s, group->mont_data, ctx)
|| !BN_mod_mul_montgomery(s, s, ckinv, group->mont_data, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
if (BN_is_zero(s)) {
/*
* if kinv and r have been supplied by the caller, don't
* generate new kinv and r values
*/
if (in_kinv != NULL && in_r != NULL) {
ERR_raise(ERR_LIB_EC, EC_R_NEED_NEW_SETUP_VALUES);
goto err;
}
/* Avoid infinite loops cause by invalid group parameters */
if (retries++ > MAX_ECDSA_SIGN_RETRIES) {
ERR_raise(ERR_LIB_EC, EC_R_TOO_MANY_RETRIES);
goto err;
}
} else {
/* s != 0 => we have a valid signature */
break;
}
} while (1);
ok = 1;
err:
if (!ok) {
ECDSA_SIG_free(ret);
ret = NULL;
}
BN_CTX_free(ctx);
BN_clear_free(m);
BN_clear_free(kinv);
return ret;
}
/*-
* returns
* 1: correct signature
* 0: incorrect signature
* -1: error
*/
int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
{
ECDSA_SIG *s;
const unsigned char *p = sigbuf;
unsigned char *der = NULL;
int derlen = -1;
int ret = -1;
s = ECDSA_SIG_new();
if (s == NULL)
return ret;
if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
goto err;
/* Ensure signature uses DER and doesn't have trailing garbage */
derlen = i2d_ECDSA_SIG(s, &der);
if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
goto err;
ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
err:
OPENSSL_free(der);
ECDSA_SIG_free(s);
return ret;
}
int ossl_ecdsa_simple_verify_sig(const unsigned char *dgst, int dgst_len,
const ECDSA_SIG *sig, EC_KEY *eckey)
{
int ret = -1, i;
BN_CTX *ctx;
const BIGNUM *order;
BIGNUM *u1, *u2, *m, *X;
EC_POINT *point = NULL;
const EC_GROUP *group;
const EC_POINT *pub_key;
/* check input values */
if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
(pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_MISSING_PARAMETERS);
return -1;
}
if (!EC_KEY_can_sign(eckey)) {
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
return -1;
}
ctx = BN_CTX_new_ex(eckey->libctx);
if (ctx == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
return -1;
}
BN_CTX_start(ctx);
u1 = BN_CTX_get(ctx);
u2 = BN_CTX_get(ctx);
m = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
if (X == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
order = EC_GROUP_get0_order(group);
if (order == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
ERR_raise(ERR_LIB_EC, EC_R_BAD_SIGNATURE);
ret = 0; /* signature is invalid */
goto err;
}
/* calculate tmp1 = inv(S) mod order */
if (!ossl_ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* digest -> m */
i = BN_num_bits(order);
/*
* Need to truncate digest if it is too long: first truncate whole bytes.
*/
if (8 * dgst_len > i)
dgst_len = (i + 7) / 8;
if (!BN_bin2bn(dgst, dgst_len, m)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* If still too long truncate remaining bits with a shift */
if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* u1 = m * tmp mod order */
if (!BN_mod_mul(u1, m, u2, order, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* u2 = r * w mod q */
if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
if ((point = EC_POINT_new(group)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (!EC_POINT_get_affine_coordinates(group, point, X, NULL, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
goto err;
}
if (!BN_nnmod(u1, X, order, ctx)) {
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
goto err;
}
/* if the signature is correct u1 is equal to sig->r */
ret = (BN_ucmp(u1, sig->r) == 0);
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
EC_POINT_free(point);
return ret;
}
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