Decrypt ciphertext and populate `self.plaintext`

Property definitions

	# Decrypt ciphertext and populate `self.plaintext`
	fun decrypt is abstract

lib/crypto/xor_ciphers.nit:62,2--63,24

	redef fun decrypt do
		var key_bytes = new Bytes.with_capacity(1)
		key_bytes.add(key)
		plaintext = ciphertext.xorcipher(key_bytes)
	end

lib/crypto/xor_ciphers.nit:80,2--84,4

	redef fun decrypt do
		assert key.length > 0
		plaintext = ciphertext.xorcipher(key)
	end

lib/crypto/xor_ciphers.nit:99,2--102,4