"""Common functions for the SSH classes.
This module is unstable.
Maintainer: U{Paul Swartz<mailto:z3p@twistedmatrix.com>}
"""
import struct
from Crypto import Util
from Crypto.Util import randpool
entropy = randpool.RandomPool()
entropy.stir()
def NS(t):
"""
net string
"""
return struct.pack('!L',len(t)) + t
def getNS(s, count=1):
"""
get net string
"""
ns = []
for i in range(count):
l = struct.unpack('!L',s[:4])[0]
ns.append(s[4:4+l])
s = s[4+l:]
return tuple(ns) + (s,)
def MP(number):
if number==0: return '\000'*4
assert number>0
bn = Util.number.long_to_bytes(number)
if ord(bn[0])&128:
bn = '\000' + bn
return struct.pack('>L',len(bn)) + bn
def getMP(data):
"""
get multiple precision integer
"""
length=struct.unpack('>L',data[:4])[0]
return Util.number.bytes_to_long(data[4:4+length]),data[4+length:]
def _MPpow(x, y, z):
"""return the MP version of (x**y)%z
"""
return MP(pow(x,y,z))
def ffs(c, s):
"""
first from second
goes through the first list, looking for items in the second, returns the first one
"""
for i in c:
if i in s: return i
getMP_py = getMP
MP_py = MP
_MPpow_py = _MPpow
pyPow = pow
def _fastgetMP(i):
l = struct.unpack('!L', i[:4])[0]
n = i[4:l+4][::-1]
return long(gmpy.mpz(n+'\x00', 256)), i[4+l:]
def _fastMP(i):
i2 = gmpy.mpz(i).binary()[::-1]
return struct.pack('!L', len(i2)) + i2
def _fastMPpow(x, y, z=None):
r = pow(gmpy.mpz(x),y,z).binary()[::-1]
return struct.pack('!L', len(r)) + r
def _fastpow(x, y, z=None):
return pyPow(gmpy.mpz(x), y, z)
try:
import gmpy
getMP = _fastgetMP
MP = _fastMP
_MPpow = _fastMPpow
__builtins__['pow'] = _fastpow except ImportError:
pass