crypto/ec/ecp_mont.c - third_party/openssl - Git at Google

 /*
  * Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
  * Copyright (c) 2002, Oracle and/or its affiliates. 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 <openssl/err.h>

 #include "ec_local.h"

 const EC_METHOD *EC_GFp_mont_method(void)
 {
     static const EC_METHOD ret = {
         EC_FLAGS_DEFAULT_OCT,
         NID_X9_62_prime_field,
         ossl_ec_GFp_mont_group_init,
         ossl_ec_GFp_mont_group_finish,
         ossl_ec_GFp_mont_group_clear_finish,
         ossl_ec_GFp_mont_group_copy,
         ossl_ec_GFp_mont_group_set_curve,
         ossl_ec_GFp_simple_group_get_curve,
         ossl_ec_GFp_simple_group_get_degree,
         ossl_ec_group_simple_order_bits,
         ossl_ec_GFp_simple_group_check_discriminant,
         ossl_ec_GFp_simple_point_init,
         ossl_ec_GFp_simple_point_finish,
         ossl_ec_GFp_simple_point_clear_finish,
         ossl_ec_GFp_simple_point_copy,
         ossl_ec_GFp_simple_point_set_to_infinity,
         ossl_ec_GFp_simple_point_set_affine_coordinates,
         ossl_ec_GFp_simple_point_get_affine_coordinates,
         0, 0, 0,
         ossl_ec_GFp_simple_add,
         ossl_ec_GFp_simple_dbl,
         ossl_ec_GFp_simple_invert,
         ossl_ec_GFp_simple_is_at_infinity,
         ossl_ec_GFp_simple_is_on_curve,
         ossl_ec_GFp_simple_cmp,
         ossl_ec_GFp_simple_make_affine,
         ossl_ec_GFp_simple_points_make_affine,
         0 /* mul */ ,
         0 /* precompute_mult */ ,
         0 /* have_precompute_mult */ ,
         ossl_ec_GFp_mont_field_mul,
         ossl_ec_GFp_mont_field_sqr,
         0 /* field_div */ ,
         ossl_ec_GFp_mont_field_inv,
         ossl_ec_GFp_mont_field_encode,
         ossl_ec_GFp_mont_field_decode,
         ossl_ec_GFp_mont_field_set_to_one,
         ossl_ec_key_simple_priv2oct,
         ossl_ec_key_simple_oct2priv,
         0, /* set private */
         ossl_ec_key_simple_generate_key,
         ossl_ec_key_simple_check_key,
         ossl_ec_key_simple_generate_public_key,
         0, /* keycopy */
         0, /* keyfinish */
         ossl_ecdh_simple_compute_key,
         ossl_ecdsa_simple_sign_setup,
         ossl_ecdsa_simple_sign_sig,
         ossl_ecdsa_simple_verify_sig,
         0, /* field_inverse_mod_ord */
         ossl_ec_GFp_simple_blind_coordinates,
         ossl_ec_GFp_simple_ladder_pre,
         ossl_ec_GFp_simple_ladder_step,
         ossl_ec_GFp_simple_ladder_post
     };

     return &ret;
 }

 int ossl_ec_GFp_mont_group_init(EC_GROUP *group)
 {
     int ok;

     ok = ossl_ec_GFp_simple_group_init(group);
     group->field_data1 = NULL;
     group->field_data2 = NULL;
     return ok;
 }

 void ossl_ec_GFp_mont_group_finish(EC_GROUP *group)
 {
     BN_MONT_CTX_free(group->field_data1);
     group->field_data1 = NULL;
     BN_free(group->field_data2);
     group->field_data2 = NULL;
     ossl_ec_GFp_simple_group_finish(group);
 }

 void ossl_ec_GFp_mont_group_clear_finish(EC_GROUP *group)
 {
     BN_MONT_CTX_free(group->field_data1);
     group->field_data1 = NULL;
     BN_clear_free(group->field_data2);
     group->field_data2 = NULL;
     ossl_ec_GFp_simple_group_clear_finish(group);
 }

 int ossl_ec_GFp_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
 {
     BN_MONT_CTX_free(dest->field_data1);
     dest->field_data1 = NULL;
     BN_clear_free(dest->field_data2);
     dest->field_data2 = NULL;

     if (!ossl_ec_GFp_simple_group_copy(dest, src))
         return 0;

     if (src->field_data1 != NULL) {
         dest->field_data1 = BN_MONT_CTX_new();
         if (dest->field_data1 == NULL)
             return 0;
         if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
             goto err;
     }
     if (src->field_data2 != NULL) {
         dest->field_data2 = BN_dup(src->field_data2);
         if (dest->field_data2 == NULL)
             goto err;
     }

     return 1;

  err:
     BN_MONT_CTX_free(dest->field_data1);
     dest->field_data1 = NULL;
     return 0;
 }

 int ossl_ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p,
                                      const BIGNUM *a, const BIGNUM *b,
                                      BN_CTX *ctx)
 {
     BN_CTX *new_ctx = NULL;
     BN_MONT_CTX *mont = NULL;
     BIGNUM *one = NULL;
     int ret = 0;

     BN_MONT_CTX_free(group->field_data1);
     group->field_data1 = NULL;
     BN_free(group->field_data2);
     group->field_data2 = NULL;

     if (ctx == NULL) {
         ctx = new_ctx = BN_CTX_new_ex(group->libctx);
         if (ctx == NULL)
             return 0;
     }

     mont = BN_MONT_CTX_new();
     if (mont == NULL)
         goto err;
     if (!BN_MONT_CTX_set(mont, p, ctx)) {
         ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
         goto err;
     }
     one = BN_new();
     if (one == NULL)
         goto err;
     if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
         goto err;

     group->field_data1 = mont;
     mont = NULL;
     group->field_data2 = one;
     one = NULL;

     ret = ossl_ec_GFp_simple_group_set_curve(group, p, a, b, ctx);

     if (!ret) {
         BN_MONT_CTX_free(group->field_data1);
         group->field_data1 = NULL;
         BN_free(group->field_data2);
         group->field_data2 = NULL;
     }

  err:
     BN_free(one);
     BN_CTX_free(new_ctx);
     BN_MONT_CTX_free(mont);
     return ret;
 }

 int ossl_ec_GFp_mont_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                                const BIGNUM *b, BN_CTX *ctx)
 {
     if (group->field_data1 == NULL) {
         ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
         return 0;
     }

     return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
 }

 int ossl_ec_GFp_mont_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                                BN_CTX *ctx)
 {
     if (group->field_data1 == NULL) {
         ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
         return 0;
     }

     return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
 }

 /*-
  * Computes the multiplicative inverse of a in GF(p), storing the result in r.
  * If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
  * We have a Mont structure, so SCA hardening is FLT inversion.
  */
 int ossl_ec_GFp_mont_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                                BN_CTX *ctx)
 {
     BIGNUM *e = NULL;
     BN_CTX *new_ctx = NULL;
     int ret = 0;

     if (group->field_data1 == NULL)
         return 0;

     if (ctx == NULL
             && (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
         return 0;

     BN_CTX_start(ctx);
     if ((e = BN_CTX_get(ctx)) == NULL)
         goto err;

     /* Inverse in constant time with Fermats Little Theorem */
     if (!BN_set_word(e, 2))
         goto err;
     if (!BN_sub(e, group->field, e))
         goto err;
     /*-
      * Exponent e is public.
      * No need for scatter-gather or BN_FLG_CONSTTIME.
      */
     if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
         goto err;

     /* throw an error on zero */
     if (BN_is_zero(r)) {
         ERR_raise(ERR_LIB_EC, EC_R_CANNOT_INVERT);
         goto err;
     }

     ret = 1;

   err:
     BN_CTX_end(ctx);
     BN_CTX_free(new_ctx);
     return ret;
 }

 int ossl_ec_GFp_mont_field_encode(const EC_GROUP *group, BIGNUM *r,
                                   const BIGNUM *a, BN_CTX *ctx)
 {
     if (group->field_data1 == NULL) {
         ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
         return 0;
     }

     return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
 }

 int ossl_ec_GFp_mont_field_decode(const EC_GROUP *group, BIGNUM *r,
                                   const BIGNUM *a, BN_CTX *ctx)
 {
     if (group->field_data1 == NULL) {
         ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
         return 0;
     }

     return BN_from_montgomery(r, a, group->field_data1, ctx);
 }

 int ossl_ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r,
                                       BN_CTX *ctx)
 {
     if (group->field_data2 == NULL) {
         ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
         return 0;
     }

     if (!BN_copy(r, group->field_data2))
         return 0;
     return 1;
 }
	/*
	* Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
	* Copyright (c) 2002, Oracle and/or its affiliates. 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 <openssl/err.h>

	#include "ec_local.h"

	const EC_METHOD *EC_GFp_mont_method(void)
	{
	static const EC_METHOD ret = {
	EC_FLAGS_DEFAULT_OCT,
	NID_X9_62_prime_field,
	ossl_ec_GFp_mont_group_init,
	ossl_ec_GFp_mont_group_finish,
	ossl_ec_GFp_mont_group_clear_finish,
	ossl_ec_GFp_mont_group_copy,
	ossl_ec_GFp_mont_group_set_curve,
	ossl_ec_GFp_simple_group_get_curve,
	ossl_ec_GFp_simple_group_get_degree,
	ossl_ec_group_simple_order_bits,
	ossl_ec_GFp_simple_group_check_discriminant,
	ossl_ec_GFp_simple_point_init,
	ossl_ec_GFp_simple_point_finish,
	ossl_ec_GFp_simple_point_clear_finish,
	ossl_ec_GFp_simple_point_copy,
	ossl_ec_GFp_simple_point_set_to_infinity,
	ossl_ec_GFp_simple_point_set_affine_coordinates,
	ossl_ec_GFp_simple_point_get_affine_coordinates,
	0, 0, 0,
	ossl_ec_GFp_simple_add,
	ossl_ec_GFp_simple_dbl,
	ossl_ec_GFp_simple_invert,
	ossl_ec_GFp_simple_is_at_infinity,
	ossl_ec_GFp_simple_is_on_curve,
	ossl_ec_GFp_simple_cmp,
	ossl_ec_GFp_simple_make_affine,
	ossl_ec_GFp_simple_points_make_affine,
	0 /* mul */ ,
	0 /* precompute_mult */ ,
	0 /* have_precompute_mult */ ,
	ossl_ec_GFp_mont_field_mul,
	ossl_ec_GFp_mont_field_sqr,
	0 /* field_div */ ,
	ossl_ec_GFp_mont_field_inv,
	ossl_ec_GFp_mont_field_encode,
	ossl_ec_GFp_mont_field_decode,
	ossl_ec_GFp_mont_field_set_to_one,
	ossl_ec_key_simple_priv2oct,
	ossl_ec_key_simple_oct2priv,
	0, /* set private */
	ossl_ec_key_simple_generate_key,
	ossl_ec_key_simple_check_key,
	ossl_ec_key_simple_generate_public_key,
	0, /* keycopy */
	0, /* keyfinish */
	ossl_ecdh_simple_compute_key,
	ossl_ecdsa_simple_sign_setup,
	ossl_ecdsa_simple_sign_sig,
	ossl_ecdsa_simple_verify_sig,
	0, /* field_inverse_mod_ord */
	ossl_ec_GFp_simple_blind_coordinates,
	ossl_ec_GFp_simple_ladder_pre,
	ossl_ec_GFp_simple_ladder_step,
	ossl_ec_GFp_simple_ladder_post
	};

	return &ret;
	}

	int ossl_ec_GFp_mont_group_init(EC_GROUP *group)
	{
	int ok;

	ok = ossl_ec_GFp_simple_group_init(group);
	group->field_data1 = NULL;
	group->field_data2 = NULL;
	return ok;
	}

	void ossl_ec_GFp_mont_group_finish(EC_GROUP *group)
	{
	BN_MONT_CTX_free(group->field_data1);
	group->field_data1 = NULL;
	BN_free(group->field_data2);
	group->field_data2 = NULL;
	ossl_ec_GFp_simple_group_finish(group);
	}

	void ossl_ec_GFp_mont_group_clear_finish(EC_GROUP *group)
	{
	BN_MONT_CTX_free(group->field_data1);
	group->field_data1 = NULL;
	BN_clear_free(group->field_data2);
	group->field_data2 = NULL;
	ossl_ec_GFp_simple_group_clear_finish(group);
	}

	int ossl_ec_GFp_mont_group_copy(EC_GROUP dest, const EC_GROUP src)
	{
	BN_MONT_CTX_free(dest->field_data1);
	dest->field_data1 = NULL;
	BN_clear_free(dest->field_data2);
	dest->field_data2 = NULL;

	if (!ossl_ec_GFp_simple_group_copy(dest, src))
	return 0;

	if (src->field_data1 != NULL) {
	dest->field_data1 = BN_MONT_CTX_new();
	if (dest->field_data1 == NULL)
	return 0;
	if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
	goto err;
	}
	if (src->field_data2 != NULL) {
	dest->field_data2 = BN_dup(src->field_data2);
	if (dest->field_data2 == NULL)
	goto err;
	}

	return 1;

	err:
	BN_MONT_CTX_free(dest->field_data1);
	dest->field_data1 = NULL;
	return 0;
	}

	int ossl_ec_GFp_mont_group_set_curve(EC_GROUP group, const BIGNUM p,
	const BIGNUM a, const BIGNUM b,
	BN_CTX *ctx)
	{
	BN_CTX *new_ctx = NULL;
	BN_MONT_CTX *mont = NULL;
	BIGNUM *one = NULL;
	int ret = 0;

	BN_MONT_CTX_free(group->field_data1);
	group->field_data1 = NULL;
	BN_free(group->field_data2);
	group->field_data2 = NULL;

	if (ctx == NULL) {
	ctx = new_ctx = BN_CTX_new_ex(group->libctx);
	if (ctx == NULL)
	return 0;
	}

	mont = BN_MONT_CTX_new();
	if (mont == NULL)
	goto err;
	if (!BN_MONT_CTX_set(mont, p, ctx)) {
	ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
	goto err;
	}
	one = BN_new();
	if (one == NULL)
	goto err;
	if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
	goto err;

	group->field_data1 = mont;
	mont = NULL;
	group->field_data2 = one;
	one = NULL;

	ret = ossl_ec_GFp_simple_group_set_curve(group, p, a, b, ctx);

	if (!ret) {
	BN_MONT_CTX_free(group->field_data1);
	group->field_data1 = NULL;
	BN_free(group->field_data2);
	group->field_data2 = NULL;
	}

	err:
	BN_free(one);
	BN_CTX_free(new_ctx);
	BN_MONT_CTX_free(mont);
	return ret;
	}

	int ossl_ec_GFp_mont_field_mul(const EC_GROUP group, BIGNUM r, const BIGNUM *a,
	const BIGNUM b, BN_CTX ctx)
	{
	if (group->field_data1 == NULL) {
	ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
	return 0;
	}

	return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
	}

	int ossl_ec_GFp_mont_field_sqr(const EC_GROUP group, BIGNUM r, const BIGNUM *a,
	BN_CTX *ctx)
	{
	if (group->field_data1 == NULL) {
	ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
	return 0;
	}

	return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
	}

	/*-
	* Computes the multiplicative inverse of a in GF(p), storing the result in r.
	* If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
	* We have a Mont structure, so SCA hardening is FLT inversion.
	*/
	int ossl_ec_GFp_mont_field_inv(const EC_GROUP group, BIGNUM r, const BIGNUM *a,
	BN_CTX *ctx)
	{
	BIGNUM *e = NULL;
	BN_CTX *new_ctx = NULL;
	int ret = 0;

	if (group->field_data1 == NULL)
	return 0;

	if (ctx == NULL
	&& (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
	return 0;

	BN_CTX_start(ctx);
	if ((e = BN_CTX_get(ctx)) == NULL)
	goto err;

	/* Inverse in constant time with Fermats Little Theorem */
	if (!BN_set_word(e, 2))
	goto err;
	if (!BN_sub(e, group->field, e))
	goto err;
	/*-
	* Exponent e is public.
	* No need for scatter-gather or BN_FLG_CONSTTIME.
	*/
	if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
	goto err;

	/* throw an error on zero */
	if (BN_is_zero(r)) {
	ERR_raise(ERR_LIB_EC, EC_R_CANNOT_INVERT);
	goto err;
	}

	ret = 1;

	err:
	BN_CTX_end(ctx);
	BN_CTX_free(new_ctx);
	return ret;
	}

	int ossl_ec_GFp_mont_field_encode(const EC_GROUP group, BIGNUM r,
	const BIGNUM a, BN_CTX ctx)
	{
	if (group->field_data1 == NULL) {
	ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
	return 0;
	}

	return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
	}

	int ossl_ec_GFp_mont_field_decode(const EC_GROUP group, BIGNUM r,
	const BIGNUM a, BN_CTX ctx)
	{
	if (group->field_data1 == NULL) {
	ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
	return 0;
	}

	return BN_from_montgomery(r, a, group->field_data1, ctx);
	}

	int ossl_ec_GFp_mont_field_set_to_one(const EC_GROUP group, BIGNUM r,
	BN_CTX *ctx)
	{
	if (group->field_data2 == NULL) {
	ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
	return 0;
	}

	if (!BN_copy(r, group->field_data2))
	return 0;
	return 1;
	}