| 0,0 → 1,55 |
|---|
| def number2string(i): |
| """Convert a number to a string |
| |
| Input: long or integer |
| Output: string (big-endian) |
| """ |
| s=hex(i)[2:].rstrip('L') |
| if len(s) % 2: |
| s = '0' + s |
| return s.decode('hex') |
| |
| def number2string_N(i, N): |
| """Convert a number to a string of fixed size |
| |
| i: long or integer |
| N: length of string |
| Output: string (big-endian) |
| """ |
| s = '%0*x' % (N*2, i) |
| return s.decode('hex') |
| |
| def string2number(i): |
| """ Convert a string to a number |
| |
| Input: string (big-endian) |
| Output: long or integer |
| """ |
| return int(i.encode('hex'),16) |
| |
| def xorstring(a,b): |
| """XOR two strings of same length |
| |
| For more complex cases, see CryptoPlus.Cipher.XOR""" |
| assert len(a) == len(b) |
| return number2string_N(string2number(a)^string2number(b), len(a)) |
| |
| class Counter(str): |
| #found here: http://www.lag.net/pipermail/paramiko/2008-February.txt |
| """Necessary for CTR chaining mode |
| |
| Initializing a counter object (ctr = Counter('xxx'), gives a value to the counter object. |
| Everytime the object is called ( ctr() ) it returns the current value and increments it by 1. |
| Input/output is a raw string. |
| |
| Counter value is big endian""" |
| def __init__(self, initial_ctr): |
| if not isinstance(initial_ctr, str): |
| raise TypeError("nonce must be str") |
| self.c = int(initial_ctr.encode('hex'), 16) |
| def __call__(self): |
| # This might be slow, but it works as a demonstration |
| ctr = ("%032x" % (self.c,)).decode('hex') |
| self.c += 1 |
| return ctr |
| |