[project @ Arch-1:robey@lag.net--2003-public%secsh--dev--1.0--base-0]

initial import

(automatically generated log message)

1 files changed, 102 insertions, 0 deletions

diff --git a/rsakey.py b/rsakey.py
new file mode 100644
index 00000000..49c1c285
--- /dev/null
+++ b/rsakey.py
@@ -0,0 +1,102 @@
+#!/usr/bin/python
+
+from message import Message
+from transport import MSG_USERAUTH_REQUEST
+from Crypto.PublicKey import RSA
+from Crypto.Hash import SHA
+from ber import BER
+from util import format_binary, inflate_long, deflate_long
+import base64
+
+class RSAKey(object):
+
+    def __init__(self, msg=None):
+        self.valid = 0
+        if (msg == None) or (msg.get_string() != 'ssh-rsa'):
+            return
+        self.e = msg.get_mpint()
+        self.n = msg.get_mpint()
+        self.size = len(deflate_long(self.n, 0))
+        self.valid = 1
+
+    def __str__(self):
+        if not self.valid:
+            return ''
+        m = Message()
+        m.add_string('ssh-rsa')
+        m.add_mpint(self.e)
+        m.add_mpint(self.n)
+        return str(m)
+
+    def get_name(self):
+        return 'ssh-rsa'
+
+    def pkcs1imify(self, data):
+        """
+        turn a 20-byte SHA1 hash into a blob of data as large as the key's N,
+        using PKCS1's \"emsa-pkcs1-v1_5\" encoding.  totally bizarre.
+        """
+        SHA1_DIGESTINFO = '\x30\x21\x30\x09\x06\x05\x2b\x0e\x03\x02\x1a\x05\x00\x04\x14'
+        filler = '\xff' * (self.size - len(SHA1_DIGESTINFO) - len(data) - 3)
+        return '\x00\x01' + filler + '\x00' + SHA1_DIGESTINFO + data
+
+    def verify_ssh_sig(self, data, msg):
+        if (not self.valid) or (msg.get_string() != 'ssh-rsa'):
+            return 0
+        sig = inflate_long(msg.get_string(), 1)
+        # verify the signature by SHA'ing the data and encrypting it using the
+        # public key.  some wackiness ensues where we "pkcs1imify" the 20-byte
+        # hash into a string as long as the RSA key.
+        hash = inflate_long(self.pkcs1imify(SHA.new(data).digest()), 1)
+        rsa = RSA.construct((long(self.n), long(self.e)))
+        return rsa.verify(hash, (sig,))
+
+    def sign_ssh_data(self, data):
+        hash = SHA.new(data).digest()
+        rsa = RSA.construct((long(self.n), long(self.e), long(self.d)))
+        sig = deflate_long(rsa.sign(self.pkcs1imify(hash), '')[0], 0)
+        m = Message()
+        m.add_string('ssh-rsa')
+        m.add_string(sig)
+        return str(m)
+
+    def read_private_key_file(self, filename):
+        # private key file contains:
+        # RSAPrivateKey = { version = 0, n, e, d, p, q, d mod p-1, d mod q-1, q**-1 mod p }
+        self.valid = 0
+        try:
+            f = open(filename, 'r')
+            lines = f.readlines()
+            f.close()
+        except:
+            return
+        if lines[0].strip() != '-----BEGIN RSA PRIVATE KEY-----':
+            return
+        try:
+            data = base64.decodestring(''.join(lines[1:-1]))
+        except:
+            return
+        keylist = BER(data).decode()
+        if (type(keylist) != type([])) or (len(keylist) < 4) or (keylist[0] != 0):
+            return
+        self.n = keylist[1]
+        self.e = keylist[2]
+        self.d = keylist[3]
+        # not really needed
+        self.p = keylist[4]
+        self.q = keylist[5]
+        self.size = len(deflate_long(self.n, 0))
+        self.valid = 1
+
+    def sign_ssh_session(self, randpool, sid, username):
+        m = Message()
+        m.add_string(sid)
+        m.add_byte(chr(MSG_USERAUTH_REQUEST))
+        m.add_string(username)
+        m.add_string('ssh-connection')
+        m.add_string('publickey')
+        m.add_boolean(1)
+        m.add_string('ssh-rsa')
+        m.add_string(str(self))
+        return self.sign_ssh_data(str(m))
+