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dolphin/Externals/polarssl/library/ecdh.c

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/*
* Elliptic curve Diffie-Hellman
*
* Copyright (C) 2006-2014, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* References:
*
* SEC1 http://www.secg.org/index.php?action=secg,docs_secg
* RFC 4492
*/
#if !defined(POLARSSL_CONFIG_FILE)
#include "polarssl/config.h"
#else
#include POLARSSL_CONFIG_FILE
#endif
#if defined(POLARSSL_ECDH_C)
#include "polarssl/ecdh.h"
/*
* Generate public key: simple wrapper around ecp_gen_keypair
*/
int ecdh_gen_public( ecp_group *grp, mpi *d, ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
return ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
}
/*
* Compute shared secret (SEC1 3.3.1)
*/
int ecdh_compute_shared( ecp_group *grp, mpi *z,
const ecp_point *Q, const mpi *d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
ecp_point P;
ecp_point_init( &P );
/*
* Make sure Q is a valid pubkey before using it
*/
MPI_CHK( ecp_check_pubkey( grp, Q ) );
MPI_CHK( ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
if( ecp_is_zero( &P ) )
{
ret = POLARSSL_ERR_ECP_BAD_INPUT_DATA;
goto cleanup;
}
MPI_CHK( mpi_copy( z, &P.X ) );
cleanup:
ecp_point_free( &P );
return( ret );
}
/*
* Initialize context
*/
void ecdh_init( ecdh_context *ctx )
{
memset( ctx, 0, sizeof( ecdh_context ) );
}
/*
* Free context
*/
void ecdh_free( ecdh_context *ctx )
{
if( ctx == NULL )
return;
ecp_group_free( &ctx->grp );
ecp_point_free( &ctx->Q );
ecp_point_free( &ctx->Qp );
ecp_point_free( &ctx->Vi );
ecp_point_free( &ctx->Vf );
mpi_free( &ctx->d );
mpi_free( &ctx->z );
mpi_free( &ctx->_d );
}
/*
* Setup and write the ServerKeyExhange parameters (RFC 4492)
* struct {
* ECParameters curve_params;
* ECPoint public;
* } ServerECDHParams;
*/
int ecdh_make_params( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
size_t grp_len, pt_len;
if( ctx == NULL || ctx->grp.pbits == 0 )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
!= 0 )
return( ret );
if( ( ret = ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
!= 0 )
return( ret );
buf += grp_len;
blen -= grp_len;
if( ( ret = ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
&pt_len, buf, blen ) ) != 0 )
return( ret );
*olen = grp_len + pt_len;
return( 0 );
}
/*
* Read the ServerKeyExhange parameters (RFC 4492)
* struct {
* ECParameters curve_params;
* ECPoint public;
* } ServerECDHParams;
*/
int ecdh_read_params( ecdh_context *ctx,
const unsigned char **buf, const unsigned char *end )
{
int ret;
if( ( ret = ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
return( ret );
if( ( ret = ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
!= 0 )
return( ret );
return( 0 );
}
/*
* Get parameters from a keypair
*/
int ecdh_get_params( ecdh_context *ctx, const ecp_keypair *key,
ecdh_side side )
{
int ret;
if( ( ret = ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
return( ret );
/* If it's not our key, just import the public part as Qp */
if( side == POLARSSL_ECDH_THEIRS )
return( ecp_copy( &ctx->Qp, &key->Q ) );
/* Our key: import public (as Q) and private parts */
if( side != POLARSSL_ECDH_OURS )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
( ret = mpi_copy( &ctx->d, &key->d ) ) != 0 )
return( ret );
return( 0 );
}
/*
* Setup and export the client public value
*/
int ecdh_make_public( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
if( ctx == NULL || ctx->grp.pbits == 0 )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
!= 0 )
return( ret );
return ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
olen, buf, blen );
}
/*
* Parse and import the client's public value
*/
int ecdh_read_public( ecdh_context *ctx,
const unsigned char *buf, size_t blen )
{
int ret;
const unsigned char *p = buf;
if( ctx == NULL )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
return( ret );
if( (size_t)( p - buf ) != blen )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
return( 0 );
}
/*
* Derive and export the shared secret
*/
int ecdh_calc_secret( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
if( ctx == NULL )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
f_rng, p_rng ) ) != 0 )
{
return( ret );
}
if( mpi_size( &ctx->z ) > blen )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
*olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
return mpi_write_binary( &ctx->z, buf, *olen );
}
#if defined(POLARSSL_SELF_TEST)
/*
* Checkup routine
*/
int ecdh_self_test( int verbose )
{
((void) verbose );
return( 0 );
}
#endif /* POLARSSL_SELF_TEST */
#endif /* POLARSSL_ECDH_C */
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