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# -*- test-case-name: twisted.conch.test.test_ssh -*-
# Copyright (c) 2001-2010 Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Common functions for the SSH classes.
Maintainer: Paul Swartz
"""
import struct, warnings
try:
from Crypto import Util
except ImportError:
warnings.warn("PyCrypto not installed, but continuing anyways!",
RuntimeWarning)
from twisted.python import randbytes
def NS(t):
"""
net string
"""
return struct.pack('!L',len(t)) + t
def getNS(s, count=1):
"""
get net string
"""
ns = []
c = 0
for i in range(count):
l, = struct.unpack('!L',s[c:c+4])
ns.append(s[c+4:4+l+c])
c += 4 + l
return tuple(ns) + (s[c:],)
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, count=1):
"""
Get multiple precision integer out of the string. A multiple precision
integer is stored as a 4-byte length followed by length bytes of the
integer. If count is specified, get count integers out of the string.
The return value is a tuple of count integers followed by the rest of
the data.
"""
mp = []
c = 0
for i in range(count):
length, = struct.unpack('>L',data[c:c+4])
mp.append(Util.number.bytes_to_long(data[c+4:c+4+length]))
c += 4 + length
return tuple(mp) + (data[c:],)
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(data, count=1):
mp = []
c = 0
for i in range(count):
length = struct.unpack('!L', data[c:c+4])[0]
mp.append(long(gmpy.mpz(data[c + 4:c + 4 + length][::-1] + '\x00', 256)))
c += length + 4
return tuple(mp) + (data[c:],)
def _fastMP(i):
i2 = gmpy.mpz(i).binary()[::-1]
return struct.pack('!L', len(i2)) + i2
def _fastMPpow(x, y, z=None):
r = pyPow(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)
def install():
global getMP, MP, _MPpow
getMP = _fastgetMP
MP = _fastMP
_MPpow = _fastMPpow
__builtins__['pow'] = _fastpow # evil evil
try:
import gmpy
install()
except ImportError:
pass
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