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Make ECDH functions actually restartable

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This commit is contained in:
Manuel Pégourié-Gonnard 2017-04-27 11:38:26 +02:00
parent 71b2c53254
commit 66ba48a3c8
3 changed files with 89 additions and 12 deletions
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3
include/mbedtls/ecdh.h
View file

@ -52,6 +52,9 @@ typedef struct
mbedtls_ecp_point Vi; /*!< blinding value (for later) */
mbedtls_ecp_point Vf; /*!< un-blinding value (for later) */
mbedtls_mpi _d; /*!< previous d (for later) */
#if defined(MBEDTLS_ECP_RESTARTABLE)
mbedtls_ecp_restart_ctx rs; /*!< restart context for EC computations */
#endif
}
mbedtls_ecdh_context;

86
library/ecdh.c
View file

@ -39,22 +39,48 @@
#include <string.h>
/*
* Generate public key: simple wrapper around mbedtls_ecp_gen_keypair
* Generate public key (restartable version)
*/
static int ecdh_gen_public_restartable( mbedtls_ecp_group *grp,
mbedtls_mpi *d, mbedtls_ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
mbedtls_ecp_restart_ctx *rs_ctx )
{
int ret;
/* If multiplication is in progress, we already generated a privkey */
#if defined(MBEDTLS_ECP_RESTARTABLE)
if( rs_ctx == NULL || rs_ctx->rsm == NULL )
#endif
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, d, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, Q, d, &grp->G,
f_rng, p_rng, rs_ctx ) );
cleanup:
return( ret );
}
/*
* Generate public key
*/
int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
return( ecdh_gen_public_restartable( grp, d, Q, f_rng, p_rng, NULL ) );
}
/*
* Compute shared secret (SEC1 3.3.1)
*/
int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
static int ecdh_compute_shared_restartable( mbedtls_ecp_group *grp,
mbedtls_mpi *z,
const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
void *p_rng,
mbedtls_ecp_restart_ctx *rs_ctx )
{
int ret;
mbedtls_ecp_point P;
@ -66,7 +92,8 @@ int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
*/
MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &P, d, Q,
f_rng, p_rng, rs_ctx ) );
if( mbedtls_ecp_is_zero( &P ) )
{
@ -82,12 +109,28 @@ cleanup:
return( ret );
}
/*
* Compute shared secret (SEC1 3.3.1)
*/
int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
return( ecdh_compute_shared_restartable( grp, z, Q, d,
f_rng, p_rng, NULL ) );
}
/*
* Initialize context
*/
void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
#if defined(MBEDTLS_ECP_RESTARTABLE)
mbedtls_ecp_restart_init( &ctx->rs );
#endif
}
/*
@ -106,6 +149,10 @@ void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
mbedtls_mpi_free( &ctx->d );
mbedtls_mpi_free( &ctx->z );
mbedtls_mpi_free( &ctx->_d );
#if defined(MBEDTLS_ECP_RESTARTABLE)
mbedtls_ecp_restart_free( &ctx->rs );
#endif
}
/*
@ -122,12 +169,17 @@ int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
{
int ret;
size_t grp_len, pt_len;
mbedtls_ecp_restart_ctx *rs_ctx = NULL;
if( ctx == NULL || ctx->grp.pbits == 0 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
!= 0 )
#if defined(MBEDTLS_ECP_RESTARTABLE)
rs_ctx = &ctx->rs;
#endif
if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
f_rng, p_rng, rs_ctx ) ) != 0 )
return( ret );
if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
@ -202,12 +254,17 @@ int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
void *p_rng )
{
int ret;
mbedtls_ecp_restart_ctx *rs_ctx = NULL;
if( ctx == NULL || ctx->grp.pbits == 0 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
!= 0 )
#if defined(MBEDTLS_ECP_RESTARTABLE)
rs_ctx = &ctx->rs;
#endif
if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
f_rng, p_rng, rs_ctx ) ) != 0 )
return( ret );
return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
@ -244,12 +301,17 @@ int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
void *p_rng )
{
int ret;
mbedtls_ecp_restart_ctx *rs_ctx = NULL;
if( ctx == NULL )
if( ctx == NULL || ctx->grp.pbits == 0 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d,
f_rng, p_rng ) ) != 0 )
#if defined(MBEDTLS_ECP_RESTARTABLE)
rs_ctx = &ctx->rs;
#endif
if( ( ret = ecdh_compute_shared_restartable( &ctx->grp,
&ctx->z, &ctx->Qp, &ctx->d, f_rng, p_rng, rs_ctx ) ) != 0 )
{
return( ret );
}

12
tests/suites/test_suite_ecdh.data
View file

@ -41,3 +41,15 @@ ecdh_exchange:MBEDTLS_ECP_DP_SECP521R1
ECDH restartable rfc 5903 p256 restart disabled
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8AFE84049C62A9C57862D1433":"C6EF9C5D78AE012A011164ACB397CE2088685D8F06BF9BE0B283AB46476BEE53":"D6840F6B42F6EDAFD13116E0E12565202FEF8E9ECE7DCE03812464D04B9442DE":0:0:0
ECDH restartable rfc 5903 p256 restart max_ops=1
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8AFE84049C62A9C57862D1433":"C6EF9C5D78AE012A011164ACB397CE2088685D8F06BF9BE0B283AB46476BEE53":"D6840F6B42F6EDAFD13116E0E12565202FEF8E9ECE7DCE03812464D04B9442DE":1:1:10000
ECDH restartable rfc 5903 p256 restart max_ops=10000
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8AFE84049C62A9C57862D1433":"C6EF9C5D78AE012A011164ACB397CE2088685D8F06BF9BE0B283AB46476BEE53":"D6840F6B42F6EDAFD13116E0E12565202FEF8E9ECE7DCE03812464D04B9442DE":10000:0:0
ECDH restartable rfc 5903 p256 restart max_ops=250
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8AFE84049C62A9C57862D1433":"C6EF9C5D78AE012A011164ACB397CE2088685D8F06BF9BE0B283AB46476BEE53":"D6840F6B42F6EDAFD13116E0E12565202FEF8E9ECE7DCE03812464D04B9442DE":250:2:32