Internal method supporting encryption and decryption functionality.

def Expandkey(key, clen):
		""" Internal method supporting encryption and decryption functionality. """
		import sha
		from string import join
		from array import array

		blocks = (clen + 19) / 20
		xkey = []
		seed = key
		for i in xrange(blocks):
			seed = sha.new(key + seed).digest()
			xkey.append(seed)
		j = join(xkey, '')
		return array('L', j)