library/ecdh.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  Elliptic curve Diffie-Hellman
  *
  *  Copyright (C) 2006-2013, 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
  */

 #include "polarssl/config.h"

 #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 );
     mpi_free      ( &ctx->d   );
     ecp_point_free( &ctx->Q   );
     ecp_point_free( &ctx->Qp  );
     mpi_free      ( &ctx->z   );
     ecp_point_free( &ctx->Vi  );
     ecp_point_free( &ctx->Vf  );
     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

 #endif /* defined(POLARSSL_ECDH_C) */
	/*
	* Elliptic curve Diffie-Hellman
	*
	* Copyright (C) 2006-2013, 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
	*/

	#include "polarssl/config.h"

	#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 );
	mpi_free ( &ctx->d );
	ecp_point_free( &ctx->Q );
	ecp_point_free( &ctx->Qp );
	mpi_free ( &ctx->z );
	ecp_point_free( &ctx->Vi );
	ecp_point_free( &ctx->Vf );
	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

	#endif /* defined(POLARSSL_ECDH_C) */