5.1. Encrypt the message STOP POLLUTION by translating the letters into numbers, applying the given encryption function, and then translating the numbers back into letters. a) f(p) (p+4) mod 26 b) f(p) (p+21) mod 26 c) f(p) (17p+22) mod 26 5.2. Decrypt these messages that were encrypted using the Caesar cipher (k=3). b) WHVW WRGDB c) HDW GLP VXP a) EOXH MHDQV 5.3. The ciphertext OIKYWVHBX was produced by encrypting a plaintext message using the Vigenre cipher with key HOT. What is the plaintext message? 5.4. Encrypt the message GOOD using the RSA system with p = 13 and q=17, translating each letter into integers and grouping together pairs of integers.