1024 lines
32 KiB
C
1024 lines
32 KiB
C
/*
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* Elliptic curve DSA
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*
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* This file is provided under the Apache License 2.0, or the
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* GNU General Public License v2.0 or later.
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*
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* **********
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* Apache License 2.0:
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* **********
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*
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* **********
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* GNU General Public License v2.0 or later:
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* **********
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*/
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/*
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* References:
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*
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* SEC1 http://www.secg.org/index.php?action=secg,docs_secg
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_ECDSA_C)
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#include "mbedtls/ecdsa.h"
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#include "mbedtls/asn1write.h"
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#include <string.h>
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#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
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#include "mbedtls/hmac_drbg.h"
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#endif
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdlib.h>
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#define mbedtls_calloc calloc
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#define mbedtls_free free
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#endif
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#include "mbedtls/platform_util.h"
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/* Parameter validation macros based on platform_util.h */
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#define ECDSA_VALIDATE_RET( cond ) \
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MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA )
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#define ECDSA_VALIDATE( cond ) \
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MBEDTLS_INTERNAL_VALIDATE( cond )
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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/*
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* Sub-context for ecdsa_verify()
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*/
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struct mbedtls_ecdsa_restart_ver
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{
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mbedtls_mpi u1, u2; /* intermediate values */
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enum { /* what to do next? */
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ecdsa_ver_init = 0, /* getting started */
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ecdsa_ver_muladd, /* muladd step */
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} state;
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};
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/*
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* Init verify restart sub-context
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*/
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static void ecdsa_restart_ver_init( mbedtls_ecdsa_restart_ver_ctx *ctx )
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{
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mbedtls_mpi_init( &ctx->u1 );
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mbedtls_mpi_init( &ctx->u2 );
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ctx->state = ecdsa_ver_init;
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}
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/*
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* Free the components of a verify restart sub-context
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*/
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static void ecdsa_restart_ver_free( mbedtls_ecdsa_restart_ver_ctx *ctx )
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{
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if( ctx == NULL )
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return;
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mbedtls_mpi_free( &ctx->u1 );
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mbedtls_mpi_free( &ctx->u2 );
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ecdsa_restart_ver_init( ctx );
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}
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/*
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* Sub-context for ecdsa_sign()
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*/
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struct mbedtls_ecdsa_restart_sig
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{
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int sign_tries;
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int key_tries;
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mbedtls_mpi k; /* per-signature random */
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mbedtls_mpi r; /* r value */
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enum { /* what to do next? */
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ecdsa_sig_init = 0, /* getting started */
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ecdsa_sig_mul, /* doing ecp_mul() */
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ecdsa_sig_modn, /* mod N computations */
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} state;
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};
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/*
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* Init verify sign sub-context
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*/
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static void ecdsa_restart_sig_init( mbedtls_ecdsa_restart_sig_ctx *ctx )
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{
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ctx->sign_tries = 0;
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ctx->key_tries = 0;
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mbedtls_mpi_init( &ctx->k );
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mbedtls_mpi_init( &ctx->r );
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ctx->state = ecdsa_sig_init;
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}
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/*
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* Free the components of a sign restart sub-context
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*/
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static void ecdsa_restart_sig_free( mbedtls_ecdsa_restart_sig_ctx *ctx )
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{
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if( ctx == NULL )
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return;
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mbedtls_mpi_free( &ctx->k );
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mbedtls_mpi_free( &ctx->r );
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}
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#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
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/*
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* Sub-context for ecdsa_sign_det()
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*/
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struct mbedtls_ecdsa_restart_det
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{
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mbedtls_hmac_drbg_context rng_ctx; /* DRBG state */
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enum { /* what to do next? */
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ecdsa_det_init = 0, /* getting started */
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ecdsa_det_sign, /* make signature */
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} state;
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};
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/*
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* Init verify sign_det sub-context
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*/
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static void ecdsa_restart_det_init( mbedtls_ecdsa_restart_det_ctx *ctx )
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{
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mbedtls_hmac_drbg_init( &ctx->rng_ctx );
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ctx->state = ecdsa_det_init;
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}
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/*
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* Free the components of a sign_det restart sub-context
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*/
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static void ecdsa_restart_det_free( mbedtls_ecdsa_restart_det_ctx *ctx )
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{
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if( ctx == NULL )
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return;
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mbedtls_hmac_drbg_free( &ctx->rng_ctx );
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ecdsa_restart_det_init( ctx );
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}
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#endif /* MBEDTLS_ECDSA_DETERMINISTIC */
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#define ECDSA_RS_ECP ( rs_ctx == NULL ? NULL : &rs_ctx->ecp )
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/* Utility macro for checking and updating ops budget */
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#define ECDSA_BUDGET( ops ) \
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MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, ECDSA_RS_ECP, ops ) );
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/* Call this when entering a function that needs its own sub-context */
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#define ECDSA_RS_ENTER( SUB ) do { \
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/* reset ops count for this call if top-level */ \
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if( rs_ctx != NULL && rs_ctx->ecp.depth++ == 0 ) \
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rs_ctx->ecp.ops_done = 0; \
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\
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/* set up our own sub-context if needed */ \
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if( mbedtls_ecp_restart_is_enabled() && \
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rs_ctx != NULL && rs_ctx->SUB == NULL ) \
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{ \
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rs_ctx->SUB = mbedtls_calloc( 1, sizeof( *rs_ctx->SUB ) ); \
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if( rs_ctx->SUB == NULL ) \
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return( MBEDTLS_ERR_ECP_ALLOC_FAILED ); \
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\
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ecdsa_restart_## SUB ##_init( rs_ctx->SUB ); \
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} \
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} while( 0 )
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/* Call this when leaving a function that needs its own sub-context */
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#define ECDSA_RS_LEAVE( SUB ) do { \
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/* clear our sub-context when not in progress (done or error) */ \
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if( rs_ctx != NULL && rs_ctx->SUB != NULL && \
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ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) \
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{ \
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ecdsa_restart_## SUB ##_free( rs_ctx->SUB ); \
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mbedtls_free( rs_ctx->SUB ); \
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rs_ctx->SUB = NULL; \
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} \
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\
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if( rs_ctx != NULL ) \
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rs_ctx->ecp.depth--; \
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} while( 0 )
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#else /* MBEDTLS_ECP_RESTARTABLE */
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#define ECDSA_RS_ECP NULL
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#define ECDSA_BUDGET( ops ) /* no-op; for compatibility */
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#define ECDSA_RS_ENTER( SUB ) (void) rs_ctx
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#define ECDSA_RS_LEAVE( SUB ) (void) rs_ctx
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#endif /* MBEDTLS_ECP_RESTARTABLE */
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#if defined(MBEDTLS_ECDSA_DETERMINISTIC) || \
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!defined(MBEDTLS_ECDSA_SIGN_ALT) || \
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!defined(MBEDTLS_ECDSA_VERIFY_ALT)
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/*
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* Derive a suitable integer for group grp from a buffer of length len
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* SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3
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*/
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static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x,
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const unsigned char *buf, size_t blen )
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{
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int ret;
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size_t n_size = ( grp->nbits + 7 ) / 8;
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size_t use_size = blen > n_size ? n_size : blen;
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MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) );
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if( use_size * 8 > grp->nbits )
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MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) );
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/* While at it, reduce modulo N */
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if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 )
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MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) );
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cleanup:
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return( ret );
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}
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#endif /* ECDSA_DETERMINISTIC || !ECDSA_SIGN_ALT || !ECDSA_VERIFY_ALT */
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#if !defined(MBEDTLS_ECDSA_SIGN_ALT)
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/*
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* Compute ECDSA signature of a hashed message (SEC1 4.1.3)
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* Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message)
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*/
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static int ecdsa_sign_restartable( mbedtls_ecp_group *grp,
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mbedtls_mpi *r, mbedtls_mpi *s,
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const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
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int (*f_rng_blind)(void *, unsigned char *, size_t),
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void *p_rng_blind,
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mbedtls_ecdsa_restart_ctx *rs_ctx )
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{
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int ret, key_tries, sign_tries;
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int *p_sign_tries = &sign_tries, *p_key_tries = &key_tries;
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mbedtls_ecp_point R;
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mbedtls_mpi k, e, t;
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mbedtls_mpi *pk = &k, *pr = r;
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/* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
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if( grp->N.p == NULL )
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return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
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/* Make sure d is in range 1..n-1 */
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if( mbedtls_mpi_cmp_int( d, 1 ) < 0 || mbedtls_mpi_cmp_mpi( d, &grp->N ) >= 0 )
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return( MBEDTLS_ERR_ECP_INVALID_KEY );
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mbedtls_ecp_point_init( &R );
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mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t );
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ECDSA_RS_ENTER( sig );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( rs_ctx != NULL && rs_ctx->sig != NULL )
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{
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/* redirect to our context */
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p_sign_tries = &rs_ctx->sig->sign_tries;
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p_key_tries = &rs_ctx->sig->key_tries;
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pk = &rs_ctx->sig->k;
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pr = &rs_ctx->sig->r;
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/* jump to current step */
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if( rs_ctx->sig->state == ecdsa_sig_mul )
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goto mul;
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if( rs_ctx->sig->state == ecdsa_sig_modn )
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goto modn;
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}
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#endif /* MBEDTLS_ECP_RESTARTABLE */
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*p_sign_tries = 0;
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do
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{
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if( (*p_sign_tries)++ > 10 )
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{
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ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
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goto cleanup;
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}
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/*
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* Steps 1-3: generate a suitable ephemeral keypair
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* and set r = xR mod n
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*/
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*p_key_tries = 0;
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do
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{
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if( (*p_key_tries)++ > 10 )
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{
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ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
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goto cleanup;
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}
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MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, pk, f_rng, p_rng ) );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( rs_ctx != NULL && rs_ctx->sig != NULL )
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rs_ctx->sig->state = ecdsa_sig_mul;
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mul:
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#endif
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MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &R, pk, &grp->G,
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f_rng_blind,
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p_rng_blind,
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ECDSA_RS_ECP ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pr, &R.X, &grp->N ) );
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}
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while( mbedtls_mpi_cmp_int( pr, 0 ) == 0 );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( rs_ctx != NULL && rs_ctx->sig != NULL )
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rs_ctx->sig->state = ecdsa_sig_modn;
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modn:
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#endif
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/*
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* Accounting for everything up to the end of the loop
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* (step 6, but checking now avoids saving e and t)
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*/
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ECDSA_BUDGET( MBEDTLS_ECP_OPS_INV + 4 );
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/*
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* Step 5: derive MPI from hashed message
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*/
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MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
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/*
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* Generate a random value to blind inv_mod in next step,
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* avoiding a potential timing leak.
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*/
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MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, &t, f_rng_blind,
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p_rng_blind ) );
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/*
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* Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n
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*/
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MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, pr, d ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pk, pk, &t ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pk, pk, &grp->N ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, pk, &grp->N ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) );
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MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) );
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}
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while( mbedtls_mpi_cmp_int( s, 0 ) == 0 );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( rs_ctx != NULL && rs_ctx->sig != NULL )
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mbedtls_mpi_copy( r, pr );
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#endif
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cleanup:
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mbedtls_ecp_point_free( &R );
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mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t );
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ECDSA_RS_LEAVE( sig );
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return( ret );
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}
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/*
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* Compute ECDSA signature of a hashed message
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*/
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int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
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const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
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{
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ECDSA_VALIDATE_RET( grp != NULL );
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ECDSA_VALIDATE_RET( r != NULL );
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ECDSA_VALIDATE_RET( s != NULL );
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ECDSA_VALIDATE_RET( d != NULL );
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ECDSA_VALIDATE_RET( f_rng != NULL );
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ECDSA_VALIDATE_RET( buf != NULL || blen == 0 );
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/* Use the same RNG for both blinding and ephemeral key generation */
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return( ecdsa_sign_restartable( grp, r, s, d, buf, blen,
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f_rng, p_rng, f_rng, p_rng, NULL ) );
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}
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#endif /* !MBEDTLS_ECDSA_SIGN_ALT */
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#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
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/*
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* Deterministic signature wrapper
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*/
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static int ecdsa_sign_det_restartable( mbedtls_ecp_group *grp,
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mbedtls_mpi *r, mbedtls_mpi *s,
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const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
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mbedtls_md_type_t md_alg,
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int (*f_rng_blind)(void *, unsigned char *, size_t),
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void *p_rng_blind,
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mbedtls_ecdsa_restart_ctx *rs_ctx )
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{
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int ret;
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mbedtls_hmac_drbg_context rng_ctx;
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mbedtls_hmac_drbg_context *p_rng = &rng_ctx;
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unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES];
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size_t grp_len = ( grp->nbits + 7 ) / 8;
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const mbedtls_md_info_t *md_info;
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mbedtls_mpi h;
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if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
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return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
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mbedtls_mpi_init( &h );
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mbedtls_hmac_drbg_init( &rng_ctx );
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ECDSA_RS_ENTER( det );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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|
if( rs_ctx != NULL && rs_ctx->det != NULL )
|
|
{
|
|
/* redirect to our context */
|
|
p_rng = &rs_ctx->det->rng_ctx;
|
|
|
|
/* jump to current step */
|
|
if( rs_ctx->det->state == ecdsa_det_sign )
|
|
goto sign;
|
|
}
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
/* Use private key and message hash (reduced) to initialize HMAC_DRBG */
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) );
|
|
MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) );
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) );
|
|
mbedtls_hmac_drbg_seed_buf( p_rng, md_info, data, 2 * grp_len );
|
|
|
|
#if defined(MBEDTLS_ECP_RESTARTABLE)
|
|
if( rs_ctx != NULL && rs_ctx->det != NULL )
|
|
rs_ctx->det->state = ecdsa_det_sign;
|
|
|
|
sign:
|
|
#endif
|
|
#if defined(MBEDTLS_ECDSA_SIGN_ALT)
|
|
ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen,
|
|
mbedtls_hmac_drbg_random, p_rng );
|
|
#else
|
|
if( f_rng_blind != NULL )
|
|
ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen,
|
|
mbedtls_hmac_drbg_random, p_rng,
|
|
f_rng_blind, p_rng_blind, rs_ctx );
|
|
else
|
|
{
|
|
mbedtls_hmac_drbg_context *p_rng_blind_det;
|
|
|
|
#if !defined(MBEDTLS_ECP_RESTARTABLE)
|
|
/*
|
|
* To avoid reusing rng_ctx and risking incorrect behavior we seed a
|
|
* second HMAC-DRBG with the same seed. We also apply a label to avoid
|
|
* reusing the bits of the ephemeral key for blinding and eliminate the
|
|
* risk that they leak this way.
|
|
*/
|
|
const char* blind_label = "BLINDING CONTEXT";
|
|
mbedtls_hmac_drbg_context rng_ctx_blind;
|
|
|
|
mbedtls_hmac_drbg_init( &rng_ctx_blind );
|
|
p_rng_blind_det = &rng_ctx_blind;
|
|
|
|
mbedtls_hmac_drbg_seed_buf( p_rng_blind_det, md_info,
|
|
data, 2 * grp_len );
|
|
ret = mbedtls_hmac_drbg_update_ret( p_rng_blind_det,
|
|
(const unsigned char*) blind_label,
|
|
strlen( blind_label ) );
|
|
if( ret != 0 )
|
|
{
|
|
mbedtls_hmac_drbg_free( &rng_ctx_blind );
|
|
goto cleanup;
|
|
}
|
|
#else
|
|
/*
|
|
* In the case of restartable computations we would either need to store
|
|
* the second RNG in the restart context too or set it up at every
|
|
* restart. The first option would penalize the correct application of
|
|
* the function and the second would defeat the purpose of the
|
|
* restartable feature.
|
|
*
|
|
* Therefore in this case we reuse the original RNG. This comes with the
|
|
* price that the resulting signature might not be a valid deterministic
|
|
* ECDSA signature with a very low probability (same magnitude as
|
|
* successfully guessing the private key). However even then it is still
|
|
* a valid ECDSA signature.
|
|
*/
|
|
p_rng_blind_det = p_rng;
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
/*
|
|
* Since the output of the RNGs is always the same for the same key and
|
|
* message, this limits the efficiency of blinding and leaks information
|
|
* through side channels. After mbedtls_ecdsa_sign_det() is removed NULL
|
|
* won't be a valid value for f_rng_blind anymore. Therefore it should
|
|
* be checked by the caller and this branch and check can be removed.
|
|
*/
|
|
ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen,
|
|
mbedtls_hmac_drbg_random, p_rng,
|
|
mbedtls_hmac_drbg_random, p_rng_blind_det,
|
|
rs_ctx );
|
|
|
|
#if !defined(MBEDTLS_ECP_RESTARTABLE)
|
|
mbedtls_hmac_drbg_free( &rng_ctx_blind );
|
|
#endif
|
|
}
|
|
#endif /* MBEDTLS_ECDSA_SIGN_ALT */
|
|
|
|
cleanup:
|
|
mbedtls_hmac_drbg_free( &rng_ctx );
|
|
mbedtls_mpi_free( &h );
|
|
|
|
ECDSA_RS_LEAVE( det );
|
|
|
|
return( ret );
|
|
}
|
|
|
|
/*
|
|
* Deterministic signature wrappers
|
|
*/
|
|
int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r,
|
|
mbedtls_mpi *s, const mbedtls_mpi *d,
|
|
const unsigned char *buf, size_t blen,
|
|
mbedtls_md_type_t md_alg )
|
|
{
|
|
ECDSA_VALIDATE_RET( grp != NULL );
|
|
ECDSA_VALIDATE_RET( r != NULL );
|
|
ECDSA_VALIDATE_RET( s != NULL );
|
|
ECDSA_VALIDATE_RET( d != NULL );
|
|
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 );
|
|
|
|
return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg,
|
|
NULL, NULL, NULL ) );
|
|
}
|
|
|
|
int mbedtls_ecdsa_sign_det_ext( mbedtls_ecp_group *grp, mbedtls_mpi *r,
|
|
mbedtls_mpi *s, const mbedtls_mpi *d,
|
|
const unsigned char *buf, size_t blen,
|
|
mbedtls_md_type_t md_alg,
|
|
int (*f_rng_blind)(void *, unsigned char *,
|
|
size_t),
|
|
void *p_rng_blind )
|
|
{
|
|
ECDSA_VALIDATE_RET( grp != NULL );
|
|
ECDSA_VALIDATE_RET( r != NULL );
|
|
ECDSA_VALIDATE_RET( s != NULL );
|
|
ECDSA_VALIDATE_RET( d != NULL );
|
|
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 );
|
|
ECDSA_VALIDATE_RET( f_rng_blind != NULL );
|
|
|
|
return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg,
|
|
f_rng_blind, p_rng_blind, NULL ) );
|
|
}
|
|
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */
|
|
|
|
#if !defined(MBEDTLS_ECDSA_VERIFY_ALT)
|
|
/*
|
|
* Verify ECDSA signature of hashed message (SEC1 4.1.4)
|
|
* Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message)
|
|
*/
|
|
static int ecdsa_verify_restartable( mbedtls_ecp_group *grp,
|
|
const unsigned char *buf, size_t blen,
|
|
const mbedtls_ecp_point *Q,
|
|
const mbedtls_mpi *r, const mbedtls_mpi *s,
|
|
mbedtls_ecdsa_restart_ctx *rs_ctx )
|
|
{
|
|
int ret;
|
|
mbedtls_mpi e, s_inv, u1, u2;
|
|
mbedtls_ecp_point R;
|
|
mbedtls_mpi *pu1 = &u1, *pu2 = &u2;
|
|
|
|
mbedtls_ecp_point_init( &R );
|
|
mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv );
|
|
mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 );
|
|
|
|
/* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */
|
|
if( grp->N.p == NULL )
|
|
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
|
|
|
|
ECDSA_RS_ENTER( ver );
|
|
|
|
#if defined(MBEDTLS_ECP_RESTARTABLE)
|
|
if( rs_ctx != NULL && rs_ctx->ver != NULL )
|
|
{
|
|
/* redirect to our context */
|
|
pu1 = &rs_ctx->ver->u1;
|
|
pu2 = &rs_ctx->ver->u2;
|
|
|
|
/* jump to current step */
|
|
if( rs_ctx->ver->state == ecdsa_ver_muladd )
|
|
goto muladd;
|
|
}
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
/*
|
|
* Step 1: make sure r and s are in range 1..n-1
|
|
*/
|
|
if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 ||
|
|
mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 )
|
|
{
|
|
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
|
|
goto cleanup;
|
|
}
|
|
|
|
/*
|
|
* Step 3: derive MPI from hashed message
|
|
*/
|
|
MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
|
|
|
|
/*
|
|
* Step 4: u1 = e / s mod n, u2 = r / s mod n
|
|
*/
|
|
ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 );
|
|
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
|
|
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu1, &e, &s_inv ) );
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu1, pu1, &grp->N ) );
|
|
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu2, r, &s_inv ) );
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu2, pu2, &grp->N ) );
|
|
|
|
#if defined(MBEDTLS_ECP_RESTARTABLE)
|
|
if( rs_ctx != NULL && rs_ctx->ver != NULL )
|
|
rs_ctx->ver->state = ecdsa_ver_muladd;
|
|
|
|
muladd:
|
|
#endif
|
|
/*
|
|
* Step 5: R = u1 G + u2 Q
|
|
*/
|
|
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd_restartable( grp,
|
|
&R, pu1, &grp->G, pu2, Q, ECDSA_RS_ECP ) );
|
|
|
|
if( mbedtls_ecp_is_zero( &R ) )
|
|
{
|
|
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
|
|
goto cleanup;
|
|
}
|
|
|
|
/*
|
|
* Step 6: convert xR to an integer (no-op)
|
|
* Step 7: reduce xR mod n (gives v)
|
|
*/
|
|
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) );
|
|
|
|
/*
|
|
* Step 8: check if v (that is, R.X) is equal to r
|
|
*/
|
|
if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 )
|
|
{
|
|
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;
|
|
goto cleanup;
|
|
}
|
|
|
|
cleanup:
|
|
mbedtls_ecp_point_free( &R );
|
|
mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv );
|
|
mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 );
|
|
|
|
ECDSA_RS_LEAVE( ver );
|
|
|
|
return( ret );
|
|
}
|
|
|
|
/*
|
|
* Verify ECDSA signature of hashed message
|
|
*/
|
|
int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
|
|
const unsigned char *buf, size_t blen,
|
|
const mbedtls_ecp_point *Q,
|
|
const mbedtls_mpi *r,
|
|
const mbedtls_mpi *s)
|
|
{
|
|
ECDSA_VALIDATE_RET( grp != NULL );
|
|
ECDSA_VALIDATE_RET( Q != NULL );
|
|
ECDSA_VALIDATE_RET( r != NULL );
|
|
ECDSA_VALIDATE_RET( s != NULL );
|
|
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 );
|
|
|
|
return( ecdsa_verify_restartable( grp, buf, blen, Q, r, s, NULL ) );
|
|
}
|
|
#endif /* !MBEDTLS_ECDSA_VERIFY_ALT */
|
|
|
|
/*
|
|
* Convert a signature (given by context) to ASN.1
|
|
*/
|
|
static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s,
|
|
unsigned char *sig, size_t *slen )
|
|
{
|
|
int ret;
|
|
unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
|
|
unsigned char *p = buf + sizeof( buf );
|
|
size_t len = 0;
|
|
|
|
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) );
|
|
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) );
|
|
|
|
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) );
|
|
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
|
|
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
|
|
|
|
memcpy( sig, p, len );
|
|
*slen = len;
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
/*
|
|
* Compute and write signature
|
|
*/
|
|
int mbedtls_ecdsa_write_signature_restartable( mbedtls_ecdsa_context *ctx,
|
|
mbedtls_md_type_t md_alg,
|
|
const unsigned char *hash, size_t hlen,
|
|
unsigned char *sig, size_t *slen,
|
|
int (*f_rng)(void *, unsigned char *, size_t),
|
|
void *p_rng,
|
|
mbedtls_ecdsa_restart_ctx *rs_ctx )
|
|
{
|
|
int ret;
|
|
mbedtls_mpi r, s;
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( hash != NULL );
|
|
ECDSA_VALIDATE_RET( sig != NULL );
|
|
ECDSA_VALIDATE_RET( slen != NULL );
|
|
|
|
mbedtls_mpi_init( &r );
|
|
mbedtls_mpi_init( &s );
|
|
|
|
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
|
|
MBEDTLS_MPI_CHK( ecdsa_sign_det_restartable( &ctx->grp, &r, &s, &ctx->d,
|
|
hash, hlen, md_alg, f_rng,
|
|
p_rng, rs_ctx ) );
|
|
#else
|
|
(void) md_alg;
|
|
|
|
#if defined(MBEDTLS_ECDSA_SIGN_ALT)
|
|
(void) rs_ctx;
|
|
|
|
MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
|
|
hash, hlen, f_rng, p_rng ) );
|
|
#else
|
|
/* Use the same RNG for both blinding and ephemeral key generation */
|
|
MBEDTLS_MPI_CHK( ecdsa_sign_restartable( &ctx->grp, &r, &s, &ctx->d,
|
|
hash, hlen, f_rng, p_rng, f_rng,
|
|
p_rng, rs_ctx ) );
|
|
#endif /* MBEDTLS_ECDSA_SIGN_ALT */
|
|
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */
|
|
|
|
MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) );
|
|
|
|
cleanup:
|
|
mbedtls_mpi_free( &r );
|
|
mbedtls_mpi_free( &s );
|
|
|
|
return( ret );
|
|
}
|
|
|
|
/*
|
|
* Compute and write signature
|
|
*/
|
|
int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx,
|
|
mbedtls_md_type_t md_alg,
|
|
const unsigned char *hash, size_t hlen,
|
|
unsigned char *sig, size_t *slen,
|
|
int (*f_rng)(void *, unsigned char *, size_t),
|
|
void *p_rng )
|
|
{
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( hash != NULL );
|
|
ECDSA_VALIDATE_RET( sig != NULL );
|
|
ECDSA_VALIDATE_RET( slen != NULL );
|
|
return( mbedtls_ecdsa_write_signature_restartable(
|
|
ctx, md_alg, hash, hlen, sig, slen, f_rng, p_rng, NULL ) );
|
|
}
|
|
|
|
#if !defined(MBEDTLS_DEPRECATED_REMOVED) && \
|
|
defined(MBEDTLS_ECDSA_DETERMINISTIC)
|
|
int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx,
|
|
const unsigned char *hash, size_t hlen,
|
|
unsigned char *sig, size_t *slen,
|
|
mbedtls_md_type_t md_alg )
|
|
{
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( hash != NULL );
|
|
ECDSA_VALIDATE_RET( sig != NULL );
|
|
ECDSA_VALIDATE_RET( slen != NULL );
|
|
return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen,
|
|
NULL, NULL ) );
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Read and check signature
|
|
*/
|
|
int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
|
|
const unsigned char *hash, size_t hlen,
|
|
const unsigned char *sig, size_t slen )
|
|
{
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( hash != NULL );
|
|
ECDSA_VALIDATE_RET( sig != NULL );
|
|
return( mbedtls_ecdsa_read_signature_restartable(
|
|
ctx, hash, hlen, sig, slen, NULL ) );
|
|
}
|
|
|
|
/*
|
|
* Restartable read and check signature
|
|
*/
|
|
int mbedtls_ecdsa_read_signature_restartable( mbedtls_ecdsa_context *ctx,
|
|
const unsigned char *hash, size_t hlen,
|
|
const unsigned char *sig, size_t slen,
|
|
mbedtls_ecdsa_restart_ctx *rs_ctx )
|
|
{
|
|
int ret;
|
|
unsigned char *p = (unsigned char *) sig;
|
|
const unsigned char *end = sig + slen;
|
|
size_t len;
|
|
mbedtls_mpi r, s;
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( hash != NULL );
|
|
ECDSA_VALIDATE_RET( sig != NULL );
|
|
|
|
mbedtls_mpi_init( &r );
|
|
mbedtls_mpi_init( &s );
|
|
|
|
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
|
|
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
|
|
{
|
|
ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
|
|
goto cleanup;
|
|
}
|
|
|
|
if( p + len != end )
|
|
{
|
|
ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
|
|
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
|
|
goto cleanup;
|
|
}
|
|
|
|
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 ||
|
|
( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 )
|
|
{
|
|
ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
|
|
goto cleanup;
|
|
}
|
|
#if defined(MBEDTLS_ECDSA_VERIFY_ALT)
|
|
(void) rs_ctx;
|
|
|
|
if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen,
|
|
&ctx->Q, &r, &s ) ) != 0 )
|
|
goto cleanup;
|
|
#else
|
|
if( ( ret = ecdsa_verify_restartable( &ctx->grp, hash, hlen,
|
|
&ctx->Q, &r, &s, rs_ctx ) ) != 0 )
|
|
goto cleanup;
|
|
#endif /* MBEDTLS_ECDSA_VERIFY_ALT */
|
|
|
|
/* At this point we know that the buffer starts with a valid signature.
|
|
* Return 0 if the buffer just contains the signature, and a specific
|
|
* error code if the valid signature is followed by more data. */
|
|
if( p != end )
|
|
ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH;
|
|
|
|
cleanup:
|
|
mbedtls_mpi_free( &r );
|
|
mbedtls_mpi_free( &s );
|
|
|
|
return( ret );
|
|
}
|
|
|
|
#if !defined(MBEDTLS_ECDSA_GENKEY_ALT)
|
|
/*
|
|
* Generate key pair
|
|
*/
|
|
int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
|
|
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
|
|
{
|
|
int ret = 0;
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( f_rng != NULL );
|
|
|
|
ret = mbedtls_ecp_group_load( &ctx->grp, gid );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
return( mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d,
|
|
&ctx->Q, f_rng, p_rng ) );
|
|
}
|
|
#endif /* !MBEDTLS_ECDSA_GENKEY_ALT */
|
|
|
|
/*
|
|
* Set context from an mbedtls_ecp_keypair
|
|
*/
|
|
int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key )
|
|
{
|
|
int ret;
|
|
ECDSA_VALIDATE_RET( ctx != NULL );
|
|
ECDSA_VALIDATE_RET( key != NULL );
|
|
|
|
if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ||
|
|
( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ||
|
|
( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 )
|
|
{
|
|
mbedtls_ecdsa_free( ctx );
|
|
}
|
|
|
|
return( ret );
|
|
}
|
|
|
|
/*
|
|
* Initialize context
|
|
*/
|
|
void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx )
|
|
{
|
|
ECDSA_VALIDATE( ctx != NULL );
|
|
|
|
mbedtls_ecp_keypair_init( ctx );
|
|
}
|
|
|
|
/*
|
|
* Free context
|
|
*/
|
|
void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx )
|
|
{
|
|
if( ctx == NULL )
|
|
return;
|
|
|
|
mbedtls_ecp_keypair_free( ctx );
|
|
}
|
|
|
|
#if defined(MBEDTLS_ECP_RESTARTABLE)
|
|
/*
|
|
* Initialize a restart context
|
|
*/
|
|
void mbedtls_ecdsa_restart_init( mbedtls_ecdsa_restart_ctx *ctx )
|
|
{
|
|
ECDSA_VALIDATE( ctx != NULL );
|
|
|
|
mbedtls_ecp_restart_init( &ctx->ecp );
|
|
|
|
ctx->ver = NULL;
|
|
ctx->sig = NULL;
|
|
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
|
|
ctx->det = NULL;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Free the components of a restart context
|
|
*/
|
|
void mbedtls_ecdsa_restart_free( mbedtls_ecdsa_restart_ctx *ctx )
|
|
{
|
|
if( ctx == NULL )
|
|
return;
|
|
|
|
mbedtls_ecp_restart_free( &ctx->ecp );
|
|
|
|
ecdsa_restart_ver_free( ctx->ver );
|
|
mbedtls_free( ctx->ver );
|
|
ctx->ver = NULL;
|
|
|
|
ecdsa_restart_sig_free( ctx->sig );
|
|
mbedtls_free( ctx->sig );
|
|
ctx->sig = NULL;
|
|
|
|
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
|
|
ecdsa_restart_det_free( ctx->det );
|
|
mbedtls_free( ctx->det );
|
|
ctx->det = NULL;
|
|
#endif
|
|
}
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
#endif /* MBEDTLS_ECDSA_C */
|