/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * Copyright (c) 2004 by Mihnea Stoenescu * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "dbutil.h" #include "algo.h" #include "buffer.h" #include "session.h" #include "kex.h" #include "ssh.h" #include "packet.h" #include "bignum.h" #include "random.h" #include "runopts.h" static void send_msg_kexdh_reply(mp_int *dh_e); /* Handle a diffie-hellman key exchange initialisation. This involves * calculating a session key reply value, and corresponding hash. These * are carried out by send_msg_kexdh_reply(). recv_msg_kexdh_init() calls * that function, then brings the new keys into use */ void recv_msg_kexdh_init() { DEF_MP_INT(dh_e); TRACE(("enter recv_msg_kexdh_init")); if (!ses.kexstate.recvkexinit) { dropbear_exit("Premature kexdh_init message received"); } m_mp_init(&dh_e); buf_getmpint(ses.payload, &dh_e); send_msg_kexdh_reply(&dh_e); mp_clear(&dh_e); send_msg_newkeys(); ses.requirenext = SSH_MSG_NEWKEYS; TRACE(("leave recv_msg_kexdh_init")); } /* Generate our side of the diffie-hellman key exchange value (dh_f), and * calculate the session key using the diffie-hellman algorithm. Following * that, the session hash is calculated, and signed with RSA or DSS. The * result is sent to the client. * * See the ietf-secsh-transport draft, section 6, for details */ static void send_msg_kexdh_reply(mp_int *dh_e) { DEF_MP_INT(dh_y); DEF_MP_INT(dh_f); TRACE(("enter send_msg_kexdh_reply")); m_mp_init_multi(&dh_y, &dh_f, NULL); gen_kexdh_vals(&dh_f, &dh_y); kexdh_comb_key(&dh_f, &dh_y, dh_e, svr_opts.hostkey); mp_clear(&dh_y); /* we can start creating the kexdh_reply packet */ CHECKCLEARTOWRITE(); buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY); buf_put_pub_key(ses.writepayload, svr_opts.hostkey, ses.newkeys->algo_hostkey); /* put f */ buf_putmpint(ses.writepayload, &dh_f); mp_clear(&dh_f); /* calc the signature */ buf_put_sign(ses.writepayload, svr_opts.hostkey, ses.newkeys->algo_hostkey, ses.hash, SHA1_HASH_SIZE); /* the SSH_MSG_KEXDH_REPLY is done */ encrypt_packet(); TRACE(("leave send_msg_kexdh_reply")); }