return int.from_bytes(value, 'big')
def int_to_bytes(value, count):
return value.to_bytes(count, 'big')
else:
# XXX: can any of these be sped up?
from binascii import hexlify, unhexlify
def bytes_to_int(value):
return int(hexlify(value), 16)
def int_to_bytes(value, count):
return unhexlify(('%%0%dx' % (count << 1)) % value)
add_doc(bytes_to_int, "decode byte string as single big-endian integer")
add_doc(int_to_bytes, "encode integer as single big-endian byte string")
def xor_bytes(left, right):
"""Perform bitwise-xor of two byte strings (must be same size)"""
return int_to_bytes(bytes_to_int(left) ^ bytes_to_int(right), len(left))
def repeat_string(source, size):
"""repeat or truncate <source> string, so it has length <size>"""
cur = len(source)
if size > cur:
mult = (size + cur - 1) // cur
return (source * mult)[:size]
else:
if PY3:
# new in py32
def bytes_to_int(value):
return int.from_bytes(value, 'big')
def int_to_bytes(value, count):
return value.to_bytes(count, 'big')
else:
# XXX: can any of these be sped up?
from binascii import hexlify, unhexlify
def bytes_to_int(value):
return int(hexlify(value),16)
def int_to_bytes(value, count):
return unhexlify(('%%0%dx' % (count<<1)) % value)
add_doc(bytes_to_int, "decode byte string as single big-endian integer")
add_doc(int_to_bytes, "encode integer as single big-endian byte string")
def xor_bytes(left, right):
"""Perform bitwise-xor of two byte strings (must be same size)"""
return int_to_bytes(bytes_to_int(left) ^ bytes_to_int(right), len(left))
def repeat_string(source, size):
"""repeat or truncate <source> string, so it has length <size>"""
cur = len(source)
if size > cur:
mult = (size+cur-1)//cur
return (source*mult)[:size]
else:
return source[:size]