'Will set the Initial Value, used in conjunction with CBC mode'

def setIV(self, IV):

    if ((not IV) or (len(IV) != self.block_size)):
        raise ValueError((('Invalid    Initial    Value    (IV),    must    be    a    multiple    of    ' + str(self.block_size)) + '    bytes'))
    IV = self._guardAgainstUnicode(IV)
    self._iv = IV
