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# 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()
class PrivateKey(object):
def __init__(self, instance):
self.instance = instance
@classmethod
def from_file(cls, filename):
fp = open(filename)
try:
first_line = fp.readline()
finally:
fp.close()
type_ = DSA if 'DSA' in first_line else RSA
instance = type_.load_key(filename)
return cls(instance)
def sign(self, data):
"""
Emulates the signing behavior of an ssh key agent.
"""
digest = MessageDigest('sha1')
digest.update(data)
my_data = digest.final()
return self.instance.sign(data)
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