Fixes #325 -- add support for Ed25519 keys

1 files changed, 136 insertions, 0 deletions

diff --git a/paramiko/ed25519key.py b/paramiko/ed25519key.py
new file mode 100644
index 00000000..bf4b9d6e
--- /dev/null
+++ b/paramiko/ed25519key.py
@@ -0,0 +1,136 @@
+# This file is part of paramiko.
+#
+# Paramiko is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+
+import nacl.signing
+
+import six
+
+from paramiko.message import Message
+from paramiko.pkey import PKey
+
+
+OPENSSH_AUTH_MAGIC = "openssh-key-v1\x00"
+
+def unpad(data):
+    padding_length = six.indexbytes(data, -1)
+    if padding_length > 16:
+        raise SSHException('Invalid key')
+    for i in range(1, padding_length + 1):
+        if six.indexbytes(data, -i) != (padding_length - i + 1):
+            raise SSHException('Invalid key')
+    return data[:-padding_length]
+
+
+class Ed25519Key(PKey):
+    def __init__(self, msg=None, data=None, filename=None, password=None):
+        verifying_key = signing_key = None
+        if msg is None and data is not None:
+            msg = Message(data)
+        if msg is not None:
+            if msg.get_text() != "ssh-ed25519":
+                raise SSHException('Invalid key')
+            verifying_key = nacl.signing.VerifyKey(msg.get_bytes(32))
+        elif filename is not None:
+            with open(filename, "rb") as f:
+                data = self._read_private_key("OPENSSH", f)
+                signing_key = self._parse_signing_key_data(data)
+
+        if signing_key is None and verifying_key is None:
+            import pdb; pdb.set_trace()
+
+        self._signing_key = signing_key
+        self._verifying_key = verifying_key
+
+
+    def _parse_signing_key_data(self, data):
+        # We may eventually want this to be usable for other key types, as
+        # OpenSSH moves to it, but for now this is just for Ed25519 keys.
+        message = Message(data)
+        if message.get_bytes(len(OPENSSH_AUTH_MAGIC)) != OPENSSH_AUTH_MAGIC:
+            raise SSHException('Invalid key')
+
+        ciphername = message.get_string()
+        kdfname = message.get_string()
+        kdfoptions = message.get_string()
+        num_keys = message.get_int()
+
+        if ciphername != "none" or kdfname != "none" or kdfoptions:
+            raise NotImplementedError("Encrypted keys are not implemented")
+
+        public_keys = []
+        for _ in range(num_keys):
+            # We don't need the public keys, fast-forward through them.
+            pubkey = Message(message.get_binary())
+            if pubkey.get_string() != 'ssh-ed25519':
+                raise SSHException('Invalid key')
+            public_keys.append(pubkey.get_binary())
+
+        message = Message(unpad(message.get_binary()))
+        if message.get_int() != message.get_int():
+            raise SSHException('Invalid key')
+
+        signing_keys = []
+        for i in range(num_keys):
+            if message.get_string() != 'ssh-ed25519':
+                raise SSHException('Invalid key')
+            # A copy of the public key, again, ignore.
+            public = message.get_binary()
+            key_data = message.get_binary()
+            # The second half of the key data is yet another copy of the public
+            # key...
+            signing_key = nacl.signing.SigningKey(key_data[:32])
+            assert (
+                signing_key.verify_key.encode() == public == public_keys[i] == key_data[32:]
+            )
+            signing_keys.append(signing_key)
+            # Comment, ignore.
+            message.get_string()
+
+        if len(signing_keys) != 1:
+            raise SSHException('Invalid key')
+        return signing_keys[0]
+
+    def asbytes(self):
+        m = Message()
+        m.add_string('ssh-ed25519')
+        m.add_bytes(self._signing_key.verify_key.encode())
+        return m.asbytes()
+
+    def get_name(self):
+        return "ssh-ed25519"
+
+    def get_bits(self):
+        return 256
+
+    def can_sign(self):
+        return self._signing_key is not None
+
+    def sign_ssh_data(self, data):
+        m = Message()
+        m.add_string('ssh-ed25519')
+        m.add_string(self._signing_key.sign(data).signature)
+        return m
+
+    def verify_ssh_sig(self, data, msg):
+        if msg.get_text() != 'ssh-ed25519':
+            return False
+
+        try:
+            self._verifying_key.verify(data, msg.get_binary())
+        except nacl.exceptions.BadSignatureError:
+            return False
+        else:
+            return True