diff options
Diffstat (limited to 'paramiko/util.py')
| -rw-r--r-- | paramiko/util.py | 38 |
1 files changed, 35 insertions, 3 deletions
diff --git a/paramiko/util.py b/paramiko/util.py index 8abdc0c..0d6a534 100644 --- a/paramiko/util.py +++ b/paramiko/util.py @@ -1,4 +1,4 @@ -# Copyright (C) 2003-2007 Robey Pointer <robey@lag.net> +# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com> # # This file is part of paramiko. # @@ -22,6 +22,7 @@ Useful functions used by the rest of paramiko. from __future__ import generators +import array from binascii import hexlify, unhexlify import sys import struct @@ -135,6 +136,8 @@ def safe_string(s): def bit_length(n): norm = deflate_long(n, 0) hbyte = ord(norm[0]) + if hbyte == 0: + return 1 bitlen = len(norm) * 8 while not (hbyte & 0x80): hbyte <<= 1 @@ -184,10 +187,10 @@ def load_host_keys(filename): return a compound dict of C{hostname -> keytype ->} L{PKey <paramiko.pkey.PKey>}. The hostname may be an IP address or DNS name. The keytype will be either C{"ssh-rsa"} or C{"ssh-dss"}. - + This type of file unfortunately doesn't exist on Windows, but on posix, it will usually be stored in C{os.path.expanduser("~/.ssh/known_hosts")}. - + Since 1.5.3, this is just a wrapper around L{HostKeys}. @param filename: name of the file to read host keys from @@ -268,3 +271,32 @@ def get_logger(name): return l +class Counter (object): + """Stateful counter for CTR mode crypto""" + def __init__(self, nbits, initial_value=1L, overflow=0L): + self.blocksize = nbits / 8 + self.overflow = overflow + # start with value - 1 so we don't have to store intermediate values when counting + # could the iv be 0? + if initial_value == 0: + self.value = array.array('c', '\xFF' * self.blocksize) + else: + x = deflate_long(initial_value - 1, add_sign_padding=False) + self.value = array.array('c', '\x00' * (self.blocksize - len(x)) + x) + + def __call__(self): + """Increament the counter and return the new value""" + i = self.blocksize - 1 + while i > -1: + c = self.value[i] = chr((ord(self.value[i]) + 1) % 256) + if c != '\x00': + return self.value.tostring() + i -= 1 + # counter reset + x = deflate_long(self.overflow, add_sign_padding=False) + self.value = array.array('c', '\x00' * (self.blocksize - len(x)) + x) + return self.value.tostring() + + def new(cls, nbits, initial_value=1L, overflow=0L): + return cls(nbits, initial_value=initial_value, overflow=overflow) + new = classmethod(new) |