1 files changed, 134 insertions, 0 deletions
diff --git a/src/ssh_audit/ssh2_kex.py b/src/ssh_audit/ssh2_kex.py
new file mode 100644
index 0000000..d71724f
--- /dev/null
+++ b/src/ssh_audit/ssh2_kex.py
@@ -0,0 +1,134 @@
+"""
+   The MIT License (MIT)
+
+   Copyright (C) 2017-2020 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
+
+   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.
+"""
+from typing import Dict, List
+from typing import Union
+
+from ssh_audit.outputbuffer import OutputBuffer
+from ssh_audit.readbuf import ReadBuf
+from ssh_audit.ssh2_kexparty import SSH2_KexParty
+from ssh_audit.writebuf import WriteBuf
+
+
+class SSH2_Kex:
+    def __init__(self, outputbuffer: 'OutputBuffer', cookie: bytes, kex_algs: List[str], key_algs: List[str], cli: 'SSH2_KexParty', srv: 'SSH2_KexParty', follows: bool, unused: int = 0) -> None:  # pylint: disable=too-many-arguments
+        self.__outputbuffer = outputbuffer
+        self.__cookie = cookie
+        self.__kex_algs = kex_algs
+        self.__key_algs = key_algs
+        self.__client = cli
+        self.__server = srv
+        self.__follows = follows
+        self.__unused = unused
+
+        self.__dh_modulus_sizes: Dict[str, int] = {}
+        self.__host_keys: Dict[str, Dict[str, Union[bytes, str, int]]] = {}
+
+    @property
+    def cookie(self) -> bytes:
+        return self.__cookie
+
+    @property
+    def kex_algorithms(self) -> List[str]:
+        return self.__kex_algs
+
+    @property
+    def key_algorithms(self) -> List[str]:
+        return self.__key_algs
+
+    # client_to_server
+    @property
+    def client(self) -> 'SSH2_KexParty':
+        return self.__client
+
+    # server_to_client
+    @property
+    def server(self) -> 'SSH2_KexParty':
+        return self.__server
+
+    @property
+    def follows(self) -> bool:
+        return self.__follows
+
+    @property
+    def unused(self) -> int:
+        return self.__unused
+
+    def set_dh_modulus_size(self, gex_alg: str, modulus_size: int) -> None:
+        self.__dh_modulus_sizes[gex_alg] = modulus_size
+
+    def dh_modulus_sizes(self) -> Dict[str, int]:
+        return self.__dh_modulus_sizes
+
+    def set_host_key(self, key_type: str, raw_hostkey_bytes: bytes, hostkey_size: int, ca_key_type: str, ca_key_size: int) -> None:
+
+        if key_type not in self.__host_keys:
+            self.__host_keys[key_type] = {'raw_hostkey_bytes': raw_hostkey_bytes, 'hostkey_size': hostkey_size, 'ca_key_type': ca_key_type, 'ca_key_size': ca_key_size}
+        else:  # A host key may only have one CA signature...
+            self.__outputbuffer.d("WARNING: called SSH2_Kex.set_host_key() multiple times with the same host key type (%s)!  Existing info: %r, %r, %r; Duplicate (ignored) info: %r, %r, %r" % (key_type, self.__host_keys[key_type]['hostkey_size'], self.__host_keys[key_type]['ca_key_type'], self.__host_keys[key_type]['ca_key_size'], hostkey_size, ca_key_type, ca_key_size))
+
+    def host_keys(self) -> Dict[str, Dict[str, Union[bytes, str, int]]]:
+        return self.__host_keys
+
+    def write(self, wbuf: 'WriteBuf') -> None:
+        wbuf.write(self.cookie)
+        wbuf.write_list(self.kex_algorithms)
+        wbuf.write_list(self.key_algorithms)
+        wbuf.write_list(self.client.encryption)
+        wbuf.write_list(self.server.encryption)
+        wbuf.write_list(self.client.mac)
+        wbuf.write_list(self.server.mac)
+        wbuf.write_list(self.client.compression)
+        wbuf.write_list(self.server.compression)
+        wbuf.write_list(self.client.languages)
+        wbuf.write_list(self.server.languages)
+        wbuf.write_bool(self.follows)
+        wbuf.write_int(self.__unused)
+
+    @property
+    def payload(self) -> bytes:
+        wbuf = WriteBuf()
+        self.write(wbuf)
+        return wbuf.write_flush()
+
+    @classmethod
+    def parse(cls, outputbuffer: 'OutputBuffer', payload: bytes) -> 'SSH2_Kex':
+        buf = ReadBuf(payload)
+        cookie = buf.read(16)
+        kex_algs = buf.read_list()
+        key_algs = buf.read_list()
+        cli_enc = buf.read_list()
+        srv_enc = buf.read_list()
+        cli_mac = buf.read_list()
+        srv_mac = buf.read_list()
+        cli_compression = buf.read_list()
+        srv_compression = buf.read_list()
+        cli_languages = buf.read_list()
+        srv_languages = buf.read_list()
+        follows = buf.read_bool()
+        unused = buf.read_int()
+        cli = SSH2_KexParty(cli_enc, cli_mac, cli_compression, cli_languages)
+        srv = SSH2_KexParty(srv_enc, srv_mac, srv_compression, srv_languages)
+        kex = cls(outputbuffer, cookie, kex_algs, key_algs, cli, srv, follows, unused)
+        return kex