static int ecdsa_verify_wrap( void *ctx, md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
const unsigned char *sig, size_t sig_len )
{
((void) md_alg);
return( ecdsa_read_signature( (ecdsa_context *) ctx,
hash, hash_len, sig, sig_len ) );
}
static int ecdsa_verify_wrap( void *ctx, md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
const unsigned char *sig, size_t sig_len )
{
int ret;
((void) md_alg);
ret = ecdsa_read_signature( (ecdsa_context *) ctx,
hash, hash_len, sig, sig_len );
if( ret == POLARSSL_ERR_ECP_SIG_LEN_MISMATCH )
return( POLARSSL_ERR_PK_SIG_LEN_MISMATCH );
return( ret );
}
int main( int argc, char *argv[] )
{
int ret;
ecdsa_context ctx_sign, ctx_verify;
entropy_context entropy;
ctr_drbg_context ctr_drbg;
unsigned char hash[] = "This should be the hash of a message.";
unsigned char sig[512];
size_t sig_len;
const char *pers = "ecdsa";
((void) argv);
ecdsa_init( &ctx_sign );
ecdsa_init( &ctx_verify );
memset(sig, 0, sizeof( sig ) );
ret = 1;
if( argc != 1 )
{
polarssl_printf( "usage: ecdsa\n" );
#if defined(_WIN32)
polarssl_printf( "\n" );
#endif
goto exit;
}
/*
* Generate a key pair for signing
*/
polarssl_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
entropy_init( &entropy );
if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
polarssl_printf( " failed\n ! ctr_drbg_init returned %d\n", ret );
goto exit;
}
polarssl_printf( " ok\n . Generating key pair..." );
fflush( stdout );
if( ( ret = ecdsa_genkey( &ctx_sign, ECPARAMS,
ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
polarssl_printf( " failed\n ! ecdsa_genkey returned %d\n", ret );
goto exit;
}
polarssl_printf( " ok (key size: %d bits)\n", (int) ctx_sign.grp.pbits );
dump_pubkey( " + Public key: ", &ctx_sign );
/*
* Sign some message hash
*/
polarssl_printf( " . Signing message..." );
fflush( stdout );
if( ( ret = ecdsa_write_signature( &ctx_sign,
hash, sizeof( hash ),
sig, &sig_len,
ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
polarssl_printf( " failed\n ! ecdsa_genkey returned %d\n", ret );
goto exit;
}
polarssl_printf( " ok (signature length = %u)\n", (unsigned int) sig_len );
dump_buf( " + Hash: ", hash, sizeof hash );
dump_buf( " + Signature: ", sig, sig_len );
/*
* Signature is serialized as defined by RFC 4492 p. 20,
* but one can also access 'r' and 's' directly from the context
*/
#ifdef POLARSSL_FS_IO
mpi_write_file( " r = ", &ctx_sign.r, 16, NULL );
mpi_write_file( " s = ", &ctx_sign.s, 16, NULL );
#endif
/*
* 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).
*/
polarssl_printf( " . Preparing verification context..." );
fflush( stdout );
if( ( ret = ecp_group_copy( &ctx_verify.grp, &ctx_sign.grp ) ) != 0 )
{
polarssl_printf( " failed\n ! ecp_group_copy returned %d\n", ret );
goto exit;
}
if( ( ret = ecp_copy( &ctx_verify.Q, &ctx_sign.Q ) ) != 0 )
{
polarssl_printf( " failed\n ! ecp_copy returned %d\n", ret );
goto exit;
}
ret = 0;
/*
* Verify signature
*/
polarssl_printf( " ok\n . Verifying signature..." );
fflush( stdout );
if( ( ret = ecdsa_read_signature( &ctx_verify,
hash, sizeof( hash ),
sig, sig_len ) ) != 0 )
{
polarssl_printf( " failed\n ! ecdsa_read_signature returned %d\n", ret );
goto exit;
}
polarssl_printf( " ok\n" );
exit:
#if defined(_WIN32)
polarssl_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
ecdsa_free( &ctx_verify );
ecdsa_free( &ctx_sign );
ctr_drbg_free( &ctr_drbg );
entropy_free( &entropy );
return( ret );
}
