Commit 6545ca7b authored by Manuel Pégourié-Gonnard's avatar Manuel Pégourié-Gonnard
Browse files

Add ECDH primitives

parent 0bad5c23
......@@ -33,9 +33,35 @@
extern "C" {
#endif
#ifdef __cplusplus
}
#endif
/**
* \brief Generate a public key
*
* \param grp ECP group
* \param d Destination MPI (secret exponent)
* \param Q Destination point (public key)
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successful,
* or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
*/
int ecdh_gen_public( const ecp_group *grp, mpi *d, ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Compute shared secret
*
* \param grp ECP group
* \param z Destination MPI (shared secret)
* \param Q Public key from other party
* \param d Our secret exponent
*
* \return 0 if successful,
* or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
*/
int ecdh_compute_shared( const ecp_group *grp, mpi *z,
const ecp_point *Q, const mpi *d );
/**
* \brief Checkup routine
......@@ -44,4 +70,8 @@ extern "C" {
*/
int ecdh_self_test( int verbose );
#ifdef __cplusplus
}
#endif
#endif
......@@ -147,11 +147,22 @@ void ecp_group_free( ecp_group *grp );
/**
* \brief Set a point to zero
*
* \param pt Destination point
*
* \return 0 if successful,
* POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
*/
int ecp_set_zero( ecp_point *pt );
/**
* \brief Tell if a point is zero
*
* \param pt Point to test
*
* \return 1 if point is zero, 0 otherwise
*/
int ecp_is_zero( ecp_point *pt );
/**
* \brief Copy the contents of point Q into P
*
......
......@@ -35,6 +35,45 @@
#include "polarssl/ecdh.h"
/*
* Generate public key: simple wrapper around ecp_gen_keypair
*/
int ecdh_gen_public( const 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( const ecp_group *grp, mpi *z,
const ecp_point *Q, const mpi *d )
{
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 ) );
if( ecp_is_zero( &P ) )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
MPI_CHK( mpi_copy( z, &P.X ) );
cleanup:
ecp_point_free( &P );
return( ret );
}
#if defined(POLARSSL_SELF_TEST)
......
......@@ -121,6 +121,14 @@ cleanup:
return( ret );
}
/*
* Tell if a point is zero
*/
int ecp_is_zero( ecp_point *pt )
{
return( mpi_cmp_int( &pt->Z, 0 ) == 0 );
}
/*
* Copy the contents of Q into P
*/
......
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