'Chaff(factor:float, blocksper:int)
factor is the number of message blocks to add chaff to,
expressed as a percentage between 0.0 and 1.0.  blocksper is
the number of chaff blocks to include for each block being
chaffed.  Thus the defaults add one chaff block to every
message block.  By changing the defaults, you can adjust how
computationally difficult it could be for an adversary to
brute-force crack the message.  The difficulty is expressed
as:
pow(blocksper, int(factor * number-of-blocks))
For ease of implementation, when factor < 1.0, only the first
int(factor*number-of-blocks) message blocks are chaffed.'

def __init__(self, factor=1.0, blocksper=1):

    if (not (0.0 <= factor <= 1.0)):
        raise ValueError, "'factor'    must    be    between    0.0    and    1.0"
    if (blocksper < 0):
        raise ValueError, "'blocksper'    must    be    zero    or    more"
    self.__factor = factor
    self.__blocksper = blocksper
