int ssh_server_ecdh_init(ssh_session session, ssh_buffer packet){ /* ECDH keys */ ssh_string q_c_string; ssh_string q_s_string; EC_KEY *ecdh_key; const EC_GROUP *group; const EC_POINT *ecdh_pubkey; bignum_CTX ctx; /* SSH host keys (rsa,dsa,ecdsa) */ ssh_key privkey; ssh_string sig_blob = NULL; int len; int rc; /* Extract the client pubkey from the init packet */ q_c_string = ssh_buffer_get_ssh_string(packet); if (q_c_string == NULL) { ssh_set_error(session,SSH_FATAL, "No Q_C ECC point in packet"); return SSH_ERROR; } session->next_crypto->ecdh_client_pubkey = q_c_string; /* Build server's keypair */ ctx = BN_CTX_new(); ecdh_key = EC_KEY_new_by_curve_name(NISTP256); if (ecdh_key == NULL) { ssh_set_error_oom(session); BN_CTX_free(ctx); return SSH_ERROR; } group = EC_KEY_get0_group(ecdh_key); EC_KEY_generate_key(ecdh_key); ecdh_pubkey = EC_KEY_get0_public_key(ecdh_key); len = EC_POINT_point2oct(group, ecdh_pubkey, POINT_CONVERSION_UNCOMPRESSED, NULL, 0, ctx); q_s_string = ssh_string_new(len); if (q_s_string == NULL) { EC_KEY_free(ecdh_key); BN_CTX_free(ctx); return SSH_ERROR; } EC_POINT_point2oct(group, ecdh_pubkey, POINT_CONVERSION_UNCOMPRESSED, ssh_string_data(q_s_string), len, ctx); BN_CTX_free(ctx); session->next_crypto->ecdh_privkey = ecdh_key; session->next_crypto->ecdh_server_pubkey = q_s_string; /* build k and session_id */ rc = ecdh_build_k(session); if (rc < 0) { ssh_set_error(session, SSH_FATAL, "Cannot build k number"); return SSH_ERROR; } /* privkey is not allocated */ rc = ssh_get_key_params(session, &privkey); if (rc == SSH_ERROR) { return SSH_ERROR; } rc = ssh_make_sessionid(session); if (rc != SSH_OK) { ssh_set_error(session, SSH_FATAL, "Could not create a session id"); return SSH_ERROR; } sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey); if (sig_blob == NULL) { ssh_set_error(session, SSH_FATAL, "Could not sign the session id"); return SSH_ERROR; } rc = ssh_buffer_pack(session->out_buffer, "bSSS", SSH2_MSG_KEXDH_REPLY, session->next_crypto->server_pubkey, /* host's pubkey */ q_s_string, /* ecdh public key */ sig_blob); /* signature blob */ ssh_string_free(sig_blob); if (rc != SSH_OK) { ssh_set_error_oom(session); return SSH_ERROR; } SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_KEXDH_REPLY sent"); rc = ssh_packet_send(session); if (rc == SSH_ERROR) { return SSH_ERROR; } /* Send the MSG_NEWKEYS */ rc = ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS); if (rc < 0) { return SSH_ERROR;; } session->dh_handshake_state = DH_STATE_NEWKEYS_SENT; rc = ssh_packet_send(session); SSH_LOG(SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent"); return rc; }
static int dh_handshake_server(ssh_session session) { ssh_key privkey; ssh_string sig_blob; ssh_string f; ssh_string pubkey_blob = NULL; int rc; if (ssh_dh_generate_y(session) < 0) { ssh_set_error(session, SSH_FATAL, "Could not create y number"); return -1; } if (ssh_dh_generate_f(session) < 0) { ssh_set_error(session, SSH_FATAL, "Could not create f number"); return -1; } f = ssh_dh_get_f(session); if (f == NULL) { ssh_set_error(session, SSH_FATAL, "Could not get the f number"); return -1; } if (ssh_get_key_params(session,&privkey) != SSH_OK){ ssh_string_free(f); return -1; } if (ssh_dh_build_k(session) < 0) { ssh_set_error(session, SSH_FATAL, "Could not import the public key"); ssh_string_free(f); return -1; } if (ssh_make_sessionid(session) != SSH_OK) { ssh_set_error(session, SSH_FATAL, "Could not create a session id"); ssh_string_free(f); return -1; } sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey); if (sig_blob == NULL) { ssh_set_error(session, SSH_FATAL, "Could not sign the session id"); ssh_string_free(f); return -1; } rc = ssh_dh_get_next_server_publickey_blob(session, &pubkey_blob); if (rc != SSH_OK) { ssh_set_error_oom(session); ssh_string_free(f); ssh_string_free(sig_blob); return -1; } rc = ssh_buffer_pack(session->out_buffer, "bSSS", SSH2_MSG_KEXDH_REPLY, pubkey_blob, f, sig_blob); ssh_string_free(f); ssh_string_free(sig_blob); ssh_string_free(pubkey_blob); if(rc != SSH_OK){ ssh_set_error_oom(session); ssh_buffer_reinit(session->out_buffer); return -1; } if (ssh_packet_send(session) == SSH_ERROR) { return -1; } if (ssh_buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) { ssh_buffer_reinit(session->out_buffer); return -1; } if (ssh_packet_send(session) == SSH_ERROR) { return -1; } SSH_LOG(SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent"); session->dh_handshake_state=DH_STATE_NEWKEYS_SENT; return 0; }