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add mbedtls crypto support
Summary: This patch adds support for mbedTLS as a crypto backend for libssh. mbedTLS is an SSL/TLS library that has been designed to mainly be used in embedded systems. It is loosely coupled and has a low memory footprint. mbedTLS also provides a cryptography library (libmbedcrypto) that can be used without the TLS modules. The patch is unfortunately quite big, since several new files had to be added. DSA is disabled at compile time, since mbedTLS doesn't support DSA Patch review and feedback would be appreciated, and if any issues or suggestions appear, I'm willing to work on them. Signed-off-by: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr> Test Plan: * The patch has been tested with a Debug and MinSizeRel build, with libssh unit tests, client tests and the pkd tests. * All the tests have been run with valgrind's memcheck, drd and helgrind tools. * The examples/samplessh client works when built with the patch. Reviewers: asn, aris Subscribers: simonsj Differential Revision: https://bugs.libssh.org/D1
This commit is contained in:
Juraj Vijtiuk
committed by
Andreas Schneider
Andreas Schneider
parent
5c3b1ee0a4
commit
778652460f
295
src/ecdh_mbedcrypto.c
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295
src/ecdh_mbedcrypto.c
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@@ -0,0 +1,295 @@
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/*
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* This file is part of the SSH Library
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*
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* Copyright (c) 2017 Sartura d.o.o.
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*
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* Author: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>
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*
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* The SSH Library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or (at your
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* option) any later version.
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*
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* The SSH Library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with the SSH Library; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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* MA 02111-1307, USA.
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*/
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#include "config.h"
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#include "libssh/session.h"
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#include "libssh/ecdh.h"
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#include "libssh/buffer.h"
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#include "libssh/ssh2.h"
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#include "libssh/dh.h"
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#include "libssh/pki.h"
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#include "libssh/bignum.h"
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#include "libssh/libmbedcrypto.h"
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#include <mbedtls/ecdh.h>
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#include <mbedtls/ecp.h>
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#ifdef HAVE_ECDH
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static mbedtls_ecp_group_id ecdh_kex_type_to_curve(enum ssh_key_exchange_e kex_type) {
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if (kex_type == SSH_KEX_ECDH_SHA2_NISTP256) {
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return MBEDTLS_ECP_DP_SECP256R1;
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} else if (kex_type == SSH_KEX_ECDH_SHA2_NISTP384) {
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return MBEDTLS_ECP_DP_SECP384R1;
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} else if (kex_type == SSH_KEX_ECDH_SHA2_NISTP521) {
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return MBEDTLS_ECP_DP_SECP521R1;
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}
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return MBEDTLS_ECP_DP_NONE;
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}
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int ssh_client_ecdh_init(ssh_session session)
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{
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ssh_string client_pubkey = NULL;
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mbedtls_ecp_group grp;
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int rc;
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mbedtls_ecp_group_id curve;
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curve = ecdh_kex_type_to_curve(session->next_crypto->kex_type);
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if (curve == MBEDTLS_ECP_DP_NONE) {
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return SSH_ERROR;
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}
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rc = ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_KEX_ECDH_INIT);
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if (rc < 0) {
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return SSH_ERROR;
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}
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session->next_crypto->ecdh_privkey = malloc(sizeof(mbedtls_ecp_keypair));
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if (session->next_crypto->ecdh_privkey == NULL) {
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return SSH_ERROR;
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}
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mbedtls_ecp_keypair_init(session->next_crypto->ecdh_privkey);
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mbedtls_ecp_group_init(&grp);
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rc = mbedtls_ecp_group_load(&grp, curve);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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rc = mbedtls_ecp_gen_keypair(&grp, &session->next_crypto->ecdh_privkey->d,
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&session->next_crypto->ecdh_privkey->Q, mbedtls_ctr_drbg_random,
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&ssh_mbedtls_ctr_drbg);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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client_pubkey = make_ecpoint_string(&grp,
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&session->next_crypto->ecdh_privkey->Q);
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if (client_pubkey == NULL) {
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rc = SSH_ERROR;
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goto out;
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}
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rc = ssh_buffer_add_ssh_string(session->out_buffer, client_pubkey);
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if (rc < 0) {
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rc = SSH_ERROR;
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goto out;
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}
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session->next_crypto->ecdh_client_pubkey = client_pubkey;
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client_pubkey = NULL;
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rc = ssh_packet_send(session);
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out:
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mbedtls_ecp_group_free(&grp);
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ssh_string_free(client_pubkey);
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return rc;
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}
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int ecdh_build_k(ssh_session session)
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{
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mbedtls_ecp_group grp;
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mbedtls_ecp_point pubkey;
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int rc;
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mbedtls_ecp_group_id curve;
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curve = ecdh_kex_type_to_curve(session->next_crypto->kex_type);
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if (curve == MBEDTLS_ECP_DP_NONE) {
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return SSH_ERROR;
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}
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mbedtls_ecp_group_init(&grp);
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mbedtls_ecp_point_init(&pubkey);
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rc = mbedtls_ecp_group_load(&grp, curve);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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if (session->server) {
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rc = mbedtls_ecp_point_read_binary(&grp, &pubkey,
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ssh_string_data(session->next_crypto->ecdh_client_pubkey),
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ssh_string_len(session->next_crypto->ecdh_client_pubkey));
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} else {
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rc = mbedtls_ecp_point_read_binary(&grp, &pubkey,
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ssh_string_data(session->next_crypto->ecdh_server_pubkey),
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ssh_string_len(session->next_crypto->ecdh_server_pubkey));
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}
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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session->next_crypto->k = malloc(sizeof(mbedtls_mpi));
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if (session->next_crypto->k == NULL) {
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rc = SSH_ERROR;
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goto out;
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}
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mbedtls_mpi_init(session->next_crypto->k);
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rc = mbedtls_ecdh_compute_shared(&grp, session->next_crypto->k, &pubkey,
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&session->next_crypto->ecdh_privkey->d, mbedtls_ctr_drbg_random,
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&ssh_mbedtls_ctr_drbg);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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out:
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mbedtls_ecp_keypair_free(session->next_crypto->ecdh_privkey);
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SAFE_FREE(session->next_crypto->ecdh_privkey);
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mbedtls_ecp_group_free(&grp);
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mbedtls_ecp_point_free(&pubkey);
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return rc;
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}
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#ifdef WITH_SERVER
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int ssh_server_ecdh_init(ssh_session session, ssh_buffer packet)
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{
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ssh_string q_c_string = NULL;
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ssh_string q_s_string = NULL;
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mbedtls_ecp_group grp;
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ssh_key privkey = NULL;
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ssh_string sig_blob = NULL;
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int rc;
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mbedtls_ecp_group_id curve;
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curve = ecdh_kex_type_to_curve(session->next_crypto->kex_type);
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if (curve == MBEDTLS_ECP_DP_NONE) {
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return SSH_ERROR;
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}
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q_c_string = ssh_buffer_get_ssh_string(packet);
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if (q_c_string == NULL) {
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ssh_set_error(session, SSH_FATAL, "No Q_C ECC point in packet");
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return SSH_ERROR;
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}
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session->next_crypto->ecdh_privkey = malloc(sizeof(mbedtls_ecp_keypair));
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if (session->next_crypto->ecdh_privkey == NULL) {
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ssh_set_error_oom(session);
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return SSH_ERROR;
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}
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session->next_crypto->ecdh_client_pubkey = q_c_string;
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mbedtls_ecp_group_init(&grp);
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mbedtls_ecp_keypair_init(session->next_crypto->ecdh_privkey);
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rc = mbedtls_ecp_group_load(&grp, curve);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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rc = mbedtls_ecp_gen_keypair(&grp, &session->next_crypto->ecdh_privkey->d,
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&session->next_crypto->ecdh_privkey->Q, mbedtls_ctr_drbg_random,
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&ssh_mbedtls_ctr_drbg);
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if (rc != 0) {
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rc = SSH_ERROR;
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goto out;
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}
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q_s_string = make_ecpoint_string(&grp, &session->next_crypto->ecdh_privkey->Q);
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if (q_s_string == NULL) {
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rc = SSH_ERROR;
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goto out;
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}
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session->next_crypto->ecdh_server_pubkey = q_s_string;
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/* build k and session_id */
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rc = ecdh_build_k(session);
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if (rc != SSH_OK) {
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ssh_set_error(session, SSH_FATAL, "Cannot build k number");
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goto out;
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}
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/* privkey is not allocated */
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rc = ssh_get_key_params(session, &privkey);
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if (rc == SSH_ERROR) {
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rc = SSH_ERROR;
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goto out;
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}
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rc = ssh_make_sessionid(session);
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if (rc != SSH_OK) {
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ssh_set_error(session, SSH_FATAL, "Could not create a session id");
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rc = SSH_ERROR;
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goto out;
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}
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sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey);
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if (sig_blob == NULL) {
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ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
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rc = SSH_ERROR;
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goto out;
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}
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rc = ssh_buffer_pack(session->out_buffer, "bSSS",
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SSH2_MSG_KEXDH_REPLY, session->next_crypto->server_pubkey,
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q_s_string,
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sig_blob);
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ssh_string_free(sig_blob);
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if (rc != SSH_OK) {
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ssh_set_error_oom(session);
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rc = SSH_ERROR;
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goto out;
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}
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SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_KEXDH_REPLY sent");
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rc = ssh_packet_send(session);
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if (rc != SSH_OK) {
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rc = SSH_ERROR;
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goto out;
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}
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rc = ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS);
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if (rc < 0) {
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rc = SSH_ERROR;
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goto out;
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}
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session->dh_handshake_state = DH_STATE_NEWKEYS_SENT;
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rc = ssh_packet_send(session);
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SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent");
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out:
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mbedtls_ecp_group_free(&grp);
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return rc;
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}
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#endif /* WITH_SERVER */
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#endif
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