def decrypt(key, filename):
	chunksize = 64*1024
	outputFile = filename[11:]
	
	with open(filename, 'rb') as infile:
		filesize = long(infile.read(16))
		IV = infile.read(16)

		decryptor = AES.new(key, AES.MODE_CBC, IV)

		with open(outputFile, 'wb') as outfile:
			while True:
				chunk = infile.read(chunksize)

				if len(chunk) == 0:
					break

				outfile.write(decryptor.decrypt(chunk))
			outfile.truncate(filesize)