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/*
* Example ECDSA program
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#include <stdlib.h>
#define mbedtls_printf printf
#define mbedtls_exit exit
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif /* MBEDTLS_PLATFORM_C */
#if defined(MBEDTLS_ECDSA_C) && \
defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/ecdsa.h"
#include "mbedtls/sha256.h"
#include <string.h>
#endif
/*
* Uncomment to show key and signature details
*/
#define VERBOSE
/*
* Uncomment to force use of a specific curve
*/
#define ECPARAMS MBEDTLS_ECP_DP_SECP192R1
#if !defined(ECPARAMS)
#define ECPARAMS mbedtls_ecp_curve_list()->grp_id
#endif
#if !defined(MBEDTLS_ECDSA_C) || !defined(MBEDTLS_SHA256_C) || \
!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C)
int main( void )
{
mbedtls_printf("MBEDTLS_ECDSA_C and/or MBEDTLS_SHA256_C and/or "
"MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C not defined\n");
mbedtls_exit( 0 );
}
#else
#if defined(VERBOSE)
static void dump_buf( const char *title, unsigned char *buf, size_t len )
{
size_t i;
mbedtls_printf( "%s", title );
for( i = 0; i < len; i++ )
mbedtls_printf("%c%c", "0123456789ABCDEF" [buf[i] / 16],
"0123456789ABCDEF" [buf[i] % 16] );
mbedtls_printf( "\n" );
}
static void dump_pubkey( const char *title, mbedtls_ecdsa_context *key )
{
unsigned char buf[300];
size_t len;
if( mbedtls_ecp_point_write_binary( &key->grp, &key->Q,
MBEDTLS_ECP_PF_UNCOMPRESSED, &len, buf, sizeof buf ) != 0 )
{
mbedtls_printf("internal error\n");
return;
}
dump_buf( title, buf, len );
}
#else
#define dump_buf( a, b, c )
#define dump_pubkey( a, b )
#endif
int main( int argc, char *argv[] )
{
int ret = 1;
int exit_code = MBEDTLS_EXIT_FAILURE;
mbedtls_ecdsa_context ctx_sign, ctx_verify;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
unsigned char message[100];
unsigned char hash[32];
unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
size_t sig_len;
const char *pers = "ecdsa";
((void) argv);
mbedtls_ecdsa_init( &ctx_sign );
mbedtls_ecdsa_init( &ctx_verify );
mbedtls_ctr_drbg_init( &ctr_drbg );
memset( sig, 0, sizeof( sig ) );
memset( message, 0x25, sizeof( message ) );
if( argc != 1 )
{
mbedtls_printf( "usage: ecdsa\n" );
#if defined(_WIN32)
mbedtls_printf( "\n" );
#endif
goto exit;
}
/*
* Generate a key pair for signing
*/
mbedtls_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
mbedtls_entropy_init( &entropy );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n . Generating key pair..." );
fflush( stdout );
if( ( ret = mbedtls_ecdsa_genkey( &ctx_sign, ECPARAMS,
mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdsa_genkey returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok (key size: %d bits)\n", (int) ctx_sign.grp.pbits );
dump_pubkey( " + Public key: ", &ctx_sign );
/*
* Compute message hash
*/
mbedtls_printf( " . Computing message hash..." );
fflush( stdout );
if( ( ret = mbedtls_sha256_ret( message, sizeof( message ), hash, 0 ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_sha256_ret returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
dump_buf( " + Hash: ", hash, sizeof( hash ) );
/*
* Sign message hash
*/
mbedtls_printf( " . Signing message hash..." );
fflush( stdout );
if( ( ret = mbedtls_ecdsa_write_signature( &ctx_sign, MBEDTLS_MD_SHA256,
hash, sizeof( hash ),
sig, &sig_len,
mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdsa_write_signature returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok (signature length = %u)\n", (unsigned int) sig_len );
dump_buf( " + Signature: ", sig, sig_len );
/*
* Transfer public information to verifying context
*
* We could use the same context for verification and signatures, but we
* chose to use a new one in order to make it clear that the verifying
* context only needs the public key (Q), and not the private key (d).
*/
mbedtls_printf( " . Preparing verification context..." );
fflush( stdout );
if( ( ret = mbedtls_ecp_group_copy( &ctx_verify.grp, &ctx_sign.grp ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecp_group_copy returned %d\n", ret );
goto exit;
}
if( ( ret = mbedtls_ecp_copy( &ctx_verify.Q, &ctx_sign.Q ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecp_copy returned %d\n", ret );
goto exit;
}
/*
* Verify signature
*/
mbedtls_printf( " ok\n . Verifying signature..." );
fflush( stdout );
if( ( ret = mbedtls_ecdsa_read_signature( &ctx_verify,
hash, sizeof( hash ),
sig, sig_len ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdsa_read_signature returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
exit_code = MBEDTLS_EXIT_SUCCESS;
exit:
#if defined(_WIN32)
mbedtls_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
mbedtls_ecdsa_free( &ctx_verify );
mbedtls_ecdsa_free( &ctx_sign );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
mbedtls_exit( exit_code );
}
#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C &&
ECPARAMS */
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