mirror of
https://github.com/yuzu-emu/mbedtls.git
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113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/*
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* Elliptic curve DSA
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*
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* Copyright (C) 2006-2013, Brainspark B.V.
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*
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* This file is part of PolarSSL (http://www.polarssl.org)
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* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
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*
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* All rights reserved.
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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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* 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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#include "polarssl/config.h"
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#if defined(POLARSSL_ECDSA_C)
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#include "polarssl/ecdsa.h"
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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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int ecdsa_sign( const ecp_group *grp, mpi *r, mpi *s,
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const 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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int ret, key_tries, sign_tries;
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size_t n_size;
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ecp_point R;
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mpi k, e;
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ecp_point_init( &R );
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mpi_init( &k );
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mpi_init( &e );
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sign_tries = 0;
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do
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{
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/*
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* Steps 1-3: generate a suitable ephemeral keypair
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*/
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key_tries = 0;
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do
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{
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MPI_CHK( ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) );
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MPI_CHK( mpi_copy( r, &R.X ) );
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if( key_tries++ > 10 )
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return( POLARSSL_ERR_ECP_GENERIC );
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}
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while( mpi_cmp_int( r, 0 ) == 0 );
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/*
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* Step 5: derive MPI from hashed message
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*/
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n_size = (grp->nbits + 7) / 8;
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MPI_CHK( mpi_read_binary( &e, buf, blen > n_size ? n_size : blen ) );
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/*
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* Step 6: compute s = (e + r * d) / k mod n
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*/
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MPI_CHK( mpi_mul_mpi( s, r, d ) );
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MPI_CHK( mpi_add_mpi( &e, &e, s ) );
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MPI_CHK( mpi_inv_mod( s, &k, &grp->N ) );
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MPI_CHK( mpi_mul_mpi( s, s, &e ) );
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MPI_CHK( mpi_mod_mpi( s, s, &grp->N ) );
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if( sign_tries++ > 10 )
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return( POLARSSL_ERR_ECP_GENERIC );
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}
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while( mpi_cmp_int( s, 0 ) == 0 );
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cleanup:
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ecp_point_free( &R );
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mpi_free( &k );
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mpi_free( &e );
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return( ret );
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}
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#if defined(POLARSSL_SELF_TEST)
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/*
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* Checkup routine
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*/
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int ecdsa_self_test( int verbose )
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{
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return( verbose++ );
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}
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#endif
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#endif /* defined(POLARSSL_ECDSA_C) */
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