diff options
Diffstat (limited to 'FreeRTOS-Labs/Source/mbedtls/library/ecdh.c')
| -rw-r--r-- | FreeRTOS-Labs/Source/mbedtls/library/ecdh.c | 680 |
1 files changed, 680 insertions, 0 deletions
diff --git a/FreeRTOS-Labs/Source/mbedtls/library/ecdh.c b/FreeRTOS-Labs/Source/mbedtls/library/ecdh.c new file mode 100644 index 000000000..1b1967a20 --- /dev/null +++ b/FreeRTOS-Labs/Source/mbedtls/library/ecdh.c @@ -0,0 +1,680 @@ +/*
+ * Elliptic curve Diffie-Hellman
+ *
+ * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+/*
+ * References:
+ *
+ * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
+ * RFC 4492
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_ECDH_C)
+
+#include "mbedtls/ecdh.h"
+#include "mbedtls/platform_util.h"
+
+#include <string.h>
+
+/* Parameter validation macros based on platform_util.h */
+#define ECDH_VALIDATE_RET( cond ) \
+ MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA )
+#define ECDH_VALIDATE( cond ) \
+ MBEDTLS_INTERNAL_VALIDATE( cond )
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed;
+#endif
+
+static mbedtls_ecp_group_id mbedtls_ecdh_grp_id(
+ const mbedtls_ecdh_context *ctx )
+{
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ctx->grp.id );
+#else
+ return( ctx->grp_id );
+#endif
+}
+
+#if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
+/*
+ * Generate public key (restartable version)
+ *
+ * Note: this internal function relies on its caller preserving the value of
+ * the output parameter 'd' across continuation calls. This would not be
+ * acceptable for a public function but is OK here as we control call sites.
+ */
+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 )
+{
+ ECDH_VALIDATE_RET( grp != NULL );
+ ECDH_VALIDATE_RET( d != NULL );
+ ECDH_VALIDATE_RET( Q != NULL );
+ ECDH_VALIDATE_RET( f_rng != NULL );
+ return( ecdh_gen_public_restartable( grp, d, Q, f_rng, p_rng, NULL ) );
+}
+#endif /* !MBEDTLS_ECDH_GEN_PUBLIC_ALT */
+
+#if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
+/*
+ * Compute shared secret (SEC1 3.3.1)
+ */
+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,
+ mbedtls_ecp_restart_ctx *rs_ctx )
+{
+ int ret;
+ mbedtls_ecp_point P;
+
+ mbedtls_ecp_point_init( &P );
+
+ MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &P, d, Q,
+ f_rng, p_rng, rs_ctx ) );
+
+ if( mbedtls_ecp_is_zero( &P ) )
+ {
+ ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ goto cleanup;
+ }
+
+ MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
+
+cleanup:
+ mbedtls_ecp_point_free( &P );
+
+ 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 )
+{
+ ECDH_VALIDATE_RET( grp != NULL );
+ ECDH_VALIDATE_RET( Q != NULL );
+ ECDH_VALIDATE_RET( d != NULL );
+ ECDH_VALIDATE_RET( z != NULL );
+ return( ecdh_compute_shared_restartable( grp, z, Q, d,
+ f_rng, p_rng, NULL ) );
+}
+#endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
+
+static void ecdh_init_internal( mbedtls_ecdh_context_mbed *ctx )
+{
+ mbedtls_ecp_group_init( &ctx->grp );
+ mbedtls_mpi_init( &ctx->d );
+ mbedtls_ecp_point_init( &ctx->Q );
+ mbedtls_ecp_point_init( &ctx->Qp );
+ mbedtls_mpi_init( &ctx->z );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ mbedtls_ecp_restart_init( &ctx->rs );
+#endif
+}
+
+/*
+ * Initialize context
+ */
+void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
+{
+ ECDH_VALIDATE( ctx != NULL );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ ecdh_init_internal( ctx );
+ mbedtls_ecp_point_init( &ctx->Vi );
+ mbedtls_ecp_point_init( &ctx->Vf );
+ mbedtls_mpi_init( &ctx->_d );
+#else
+ memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
+
+ ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
+#endif
+ ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ ctx->restart_enabled = 0;
+#endif
+}
+
+static int ecdh_setup_internal( mbedtls_ecdh_context_mbed *ctx,
+ mbedtls_ecp_group_id grp_id )
+{
+ int ret;
+
+ ret = mbedtls_ecp_group_load( &ctx->grp, grp_id );
+ if( ret != 0 )
+ {
+ return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+ }
+
+ return( 0 );
+}
+
+/*
+ * Setup context
+ */
+int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id )
+{
+ ECDH_VALIDATE_RET( ctx != NULL );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_setup_internal( ctx, grp_id ) );
+#else
+ switch( grp_id )
+ {
+ default:
+ ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+ ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
+ ctx->grp_id = grp_id;
+ ecdh_init_internal( &ctx->ctx.mbed_ecdh );
+ return( ecdh_setup_internal( &ctx->ctx.mbed_ecdh, grp_id ) );
+ }
+#endif
+}
+
+static void ecdh_free_internal( mbedtls_ecdh_context_mbed *ctx )
+{
+ mbedtls_ecp_group_free( &ctx->grp );
+ mbedtls_mpi_free( &ctx->d );
+ mbedtls_ecp_point_free( &ctx->Q );
+ mbedtls_ecp_point_free( &ctx->Qp );
+ mbedtls_mpi_free( &ctx->z );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ mbedtls_ecp_restart_free( &ctx->rs );
+#endif
+}
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/*
+ * Enable restartable operations for context
+ */
+void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx )
+{
+ ECDH_VALIDATE( ctx != NULL );
+
+ ctx->restart_enabled = 1;
+}
+#endif
+
+/*
+ * Free context
+ */
+void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
+{
+ if( ctx == NULL )
+ return;
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ mbedtls_ecp_point_free( &ctx->Vi );
+ mbedtls_ecp_point_free( &ctx->Vf );
+ mbedtls_mpi_free( &ctx->_d );
+ ecdh_free_internal( ctx );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ ecdh_free_internal( &ctx->ctx.mbed_ecdh );
+ break;
+ default:
+ break;
+ }
+
+ ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+ ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
+ ctx->grp_id = MBEDTLS_ECP_DP_NONE;
+#endif
+}
+
+static int ecdh_make_params_internal( mbedtls_ecdh_context_mbed *ctx,
+ size_t *olen, int point_format,
+ unsigned char *buf, size_t blen,
+ int (*f_rng)(void *,
+ unsigned char *,
+ size_t),
+ void *p_rng,
+ int restart_enabled )
+{
+ int ret;
+ size_t grp_len, pt_len;
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ mbedtls_ecp_restart_ctx *rs_ctx = NULL;
+#endif
+
+ if( ctx->grp.pbits == 0 )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( restart_enabled )
+ rs_ctx = &ctx->rs;
+#else
+ (void) restart_enabled;
+#endif
+
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
+ f_rng, p_rng, rs_ctx ) ) != 0 )
+ return( ret );
+#else
+ if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q,
+ f_rng, p_rng ) ) != 0 )
+ return( ret );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+ if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf,
+ blen ) ) != 0 )
+ return( ret );
+
+ buf += grp_len;
+ blen -= grp_len;
+
+ if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format,
+ &pt_len, buf, blen ) ) != 0 )
+ return( ret );
+
+ *olen = grp_len + pt_len;
+ return( 0 );
+}
+
+/*
+ * Setup and write the ServerKeyExhange parameters (RFC 4492)
+ * struct {
+ * ECParameters curve_params;
+ * ECPoint public;
+ * } ServerECDHParams;
+ */
+int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ int restart_enabled = 0;
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( olen != NULL );
+ ECDH_VALIDATE_RET( buf != NULL );
+ ECDH_VALIDATE_RET( f_rng != NULL );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ restart_enabled = ctx->restart_enabled;
+#else
+ (void) restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_make_params_internal( ctx, olen, ctx->point_format, buf, blen,
+ f_rng, p_rng, restart_enabled ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_make_params_internal( &ctx->ctx.mbed_ecdh, olen,
+ ctx->point_format, buf, blen,
+ f_rng, p_rng,
+ restart_enabled ) );
+ default:
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+#endif
+}
+
+static int ecdh_read_params_internal( mbedtls_ecdh_context_mbed *ctx,
+ const unsigned char **buf,
+ const unsigned char *end )
+{
+ return( mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf,
+ end - *buf ) );
+}
+
+/*
+ * Read the ServerKeyExhange parameters (RFC 4492)
+ * struct {
+ * ECParameters curve_params;
+ * ECPoint public;
+ * } ServerECDHParams;
+ */
+int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
+ const unsigned char **buf,
+ const unsigned char *end )
+{
+ int ret;
+ mbedtls_ecp_group_id grp_id;
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( buf != NULL );
+ ECDH_VALIDATE_RET( *buf != NULL );
+ ECDH_VALIDATE_RET( end != NULL );
+
+ if( ( ret = mbedtls_ecp_tls_read_group_id( &grp_id, buf, end - *buf ) )
+ != 0 )
+ return( ret );
+
+ if( ( ret = mbedtls_ecdh_setup( ctx, grp_id ) ) != 0 )
+ return( ret );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_read_params_internal( ctx, buf, end ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_read_params_internal( &ctx->ctx.mbed_ecdh,
+ buf, end ) );
+ default:
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+#endif
+}
+
+static int ecdh_get_params_internal( mbedtls_ecdh_context_mbed *ctx,
+ const mbedtls_ecp_keypair *key,
+ mbedtls_ecdh_side side )
+{
+ int ret;
+
+ /* If it's not our key, just import the public part as Qp */
+ if( side == MBEDTLS_ECDH_THEIRS )
+ return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
+
+ /* Our key: import public (as Q) and private parts */
+ if( side != MBEDTLS_ECDH_OURS )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
+ ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
+ return( ret );
+
+ return( 0 );
+}
+
+/*
+ * Get parameters from a keypair
+ */
+int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx,
+ const mbedtls_ecp_keypair *key,
+ mbedtls_ecdh_side side )
+{
+ int ret;
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( key != NULL );
+ ECDH_VALIDATE_RET( side == MBEDTLS_ECDH_OURS ||
+ side == MBEDTLS_ECDH_THEIRS );
+
+ if( mbedtls_ecdh_grp_id( ctx ) == MBEDTLS_ECP_DP_NONE )
+ {
+ /* This is the first call to get_params(). Set up the context
+ * for use with the group. */
+ if( ( ret = mbedtls_ecdh_setup( ctx, key->grp.id ) ) != 0 )
+ return( ret );
+ }
+ else
+ {
+ /* This is not the first call to get_params(). Check that the
+ * current key's group is the same as the context's, which was set
+ * from the first key's group. */
+ if( mbedtls_ecdh_grp_id( ctx ) != key->grp.id )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+ }
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_get_params_internal( ctx, key, side ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_get_params_internal( &ctx->ctx.mbed_ecdh,
+ key, side ) );
+ default:
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+#endif
+}
+
+static int ecdh_make_public_internal( mbedtls_ecdh_context_mbed *ctx,
+ size_t *olen, int point_format,
+ unsigned char *buf, size_t blen,
+ int (*f_rng)(void *,
+ unsigned char *,
+ size_t),
+ void *p_rng,
+ int restart_enabled )
+{
+ int ret;
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ mbedtls_ecp_restart_ctx *rs_ctx = NULL;
+#endif
+
+ if( ctx->grp.pbits == 0 )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( restart_enabled )
+ rs_ctx = &ctx->rs;
+#else
+ (void) restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
+ f_rng, p_rng, rs_ctx ) ) != 0 )
+ return( ret );
+#else
+ if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q,
+ f_rng, p_rng ) ) != 0 )
+ return( ret );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+ return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format, olen,
+ buf, blen );
+}
+
+/*
+ * Setup and export the client public value
+ */
+int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ int restart_enabled = 0;
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( olen != NULL );
+ ECDH_VALIDATE_RET( buf != NULL );
+ ECDH_VALIDATE_RET( f_rng != NULL );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ restart_enabled = ctx->restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_make_public_internal( ctx, olen, ctx->point_format, buf, blen,
+ f_rng, p_rng, restart_enabled ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_make_public_internal( &ctx->ctx.mbed_ecdh, olen,
+ ctx->point_format, buf, blen,
+ f_rng, p_rng,
+ restart_enabled ) );
+ default:
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+#endif
+}
+
+static int ecdh_read_public_internal( mbedtls_ecdh_context_mbed *ctx,
+ const unsigned char *buf, size_t blen )
+{
+ int ret;
+ const unsigned char *p = buf;
+
+ if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p,
+ blen ) ) != 0 )
+ return( ret );
+
+ if( (size_t)( p - buf ) != blen )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ return( 0 );
+}
+
+/*
+ * Parse and import the client's public value
+ */
+int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
+ const unsigned char *buf, size_t blen )
+{
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( buf != NULL );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_read_public_internal( ctx, buf, blen ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_read_public_internal( &ctx->ctx.mbed_ecdh,
+ buf, blen ) );
+ default:
+ return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+ }
+#endif
+}
+
+static int ecdh_calc_secret_internal( mbedtls_ecdh_context_mbed *ctx,
+ size_t *olen, unsigned char *buf,
+ size_t blen,
+ int (*f_rng)(void *,
+ unsigned char *,
+ size_t),
+ void *p_rng,
+ int restart_enabled )
+{
+ int ret;
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ mbedtls_ecp_restart_ctx *rs_ctx = NULL;
+#endif
+
+ if( ctx == NULL || ctx->grp.pbits == 0 )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( restart_enabled )
+ rs_ctx = &ctx->rs;
+#else
+ (void) restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ if( ( ret = ecdh_compute_shared_restartable( &ctx->grp, &ctx->z, &ctx->Qp,
+ &ctx->d, f_rng, p_rng,
+ rs_ctx ) ) != 0 )
+ {
+ return( ret );
+ }
+#else
+ if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp,
+ &ctx->d, f_rng, p_rng ) ) != 0 )
+ {
+ return( ret );
+ }
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+ if( mbedtls_mpi_size( &ctx->z ) > blen )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
+
+ if( mbedtls_ecp_get_type( &ctx->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY )
+ return mbedtls_mpi_write_binary_le( &ctx->z, buf, *olen );
+
+ return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
+}
+
+/*
+ * Derive and export the shared secret
+ */
+int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
+ unsigned char *buf, size_t blen,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng )
+{
+ int restart_enabled = 0;
+ ECDH_VALIDATE_RET( ctx != NULL );
+ ECDH_VALIDATE_RET( olen != NULL );
+ ECDH_VALIDATE_RET( buf != NULL );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+ restart_enabled = ctx->restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+ return( ecdh_calc_secret_internal( ctx, olen, buf, blen, f_rng, p_rng,
+ restart_enabled ) );
+#else
+ switch( ctx->var )
+ {
+ case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+ return( ecdh_calc_secret_internal( &ctx->ctx.mbed_ecdh, olen, buf,
+ blen, f_rng, p_rng,
+ restart_enabled ) );
+ default:
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+ }
+#endif
+}
+
+#endif /* MBEDTLS_ECDH_C */
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