A fifth$-$grade teacher shows the class a message encrypted using ROT$13.$ After explaining how it works, the teacher challenges them to decrypt the message, which they easily accomplish. The teacher then repeats the process with the XOR cipher. Which of the following statements is true? Select two.

a$.$ ROT$13$ uses transposition.

b$.$ XOR uses a form of metadata.

c$.$ Both methods use substitution.

d$.$ XOR requires some type of key.

e$.$ The class easily decrypts XOR messages.