1 files changed, 88 insertions, 0 deletions

diff --git a/hgsshsign/keys.py b/hgsshsign/keys.py
new file mode 100644
index 0000000..d15af08
--- /dev/null
+++ b/hgsshsign/keys.py
@@ -0,0 +1,88 @@
+# vim: set filencoding=utf8
+"""
+Key Loader Functions
+
+@author: Mike Crute (mcrute@gmail.com)
+@organization: SoftGroup Interactive, Inc.
+@date: May 05, 2010
+"""
+
+import os
+from M2Crypto import RSA, DSA
+from M2Crypto.EVP import MessageDigest
+from M2Crypto.RSA import RSAError
+from M2Crypto.DSA import DSAError
+from structutils import unpack_string, get_packed_mp_ints, int_to_bytes
+
+
+class PublicKey(object):
+
+    def __init__(self, hashed=None, instance=None, key_type=None):
+        self.instance = instance
+        self.hashed = hashed
+        self.key_type = key_type
+
+    @property
+    def blob(self):
+        return self.hashed.decode('base64')
+
+    def verify(self, data, signature):
+        try:
+            return bool(self.instance.verify(data, signature))
+        except (RSAError, DSAError):
+            return False
+
+    def sign(self, data):
+        return self.instance.sign(data)
+
+    @classmethod
+    def from_string(cls, key):
+        """
+        Loads an RFC 4716 formatted public key.
+        """
+        pubkey = cls()
+
+        if key.startswith('ssh-'):
+            pubkey.hashed = key.split()[1]
+        else:
+            pubkey.hashed = key
+
+        pubkey.key_type, remainder = unpack_string(pubkey.blob)
+
+        if pubkey.key_type == 'ssh-rsa':
+            e, n = get_packed_mp_ints(remainder, 2)
+            pubkey.instance = RSA.new_pub_key((e, n))
+        elif pubkey.key_type == 'ssh-dss':
+            p, q, g, y = get_packed_mp_ints(remainder, 4)
+            pubkey.instance = DSA.set_params(p, q, g)
+
+        return pubkey
+
+    @classmethod
+    def from_file(cls, filename):
+        fp = open(filename)
+        try:
+            return cls.from_string(fp.read())
+        finally:
+            fp.close()
+
+
+def load_private_key(filename):
+    fp = open(filename)
+    try:
+        first_line = fp.readline()
+    finally:
+        fp.close()
+
+    type = DSA if 'DSA' in first_line else RSA
+    return type.load_key(filename)
+
+
+def sign_like_agent(data, key):
+    """
+    Emulates the signing behavior of an ssh key agent.
+    """
+    digest = MessageDigest('sha1')
+    digest.update(data)
+    my_data = digest.final()
+    return key.sign(data)