# Can both substitution and transposition ciphers be thought of as permutations?

I came across this problem to 'explain why both substitution and transposition ciphers can be thought of as permutations' and I cannot come up with an explanation to how substitution ciphers can be thought of as permutations. Can somebody provide an explanation to this? It would really help me get a better understanding.

Edit: This question is from the book Cryptography and Network Security by Behrouz Forouzan.

• Oh sweet. They have really good explanations. Thanks a lot. – Javascriptonian Sep 4 '18 at 9:58