Encoding a sentence

When talking to a friend of yours, you’d like to encode your messages so that other people don’t understand them. You get together with your friend Alice and decide to send messages to each other after following a secret algorithm that you came up with. Given an English sentence, you’ve decided to shift all the consonant letters (B, C, D, F, G, H, J, K, L, M, N, P, Q, R, S, T, V, W, X, Z) cyclically, while leaving all the vowels untouched. You hope that this will prevent other people from reading your conversations. Yet, encoding and decoding the messages every time yourself is tedious. So, you decide to implement the algorithm to make sure the messages get encoded instantly.