Solve all parts a,b,c,d & e step by step

Plaintext is encrypted using an affine cipher. A plaintext symbol, x, is drawn from Z30 and, hence, encryption is defined as y=ax+bmod30, where y is the resulting ciphertext and the encryption key is given by kenc=(a,b). (a) Determine the size of the key space (that is, the total number of keys). (b) Determine all values in Z30 that have inverses and, by trial-and-error, determine the inverses. (c) An attacker intercepts the following plaintext/ciphertext pairs: Determine the encryption key kenc=(a,b). (d) Determine the decryption key kdec=(c,d), where x=cy+dmod30. (e) Describe a simple chosen plaintext attack on the affine cipher that finds the encryption key. (The idea of a "simple" attack should be to minimize the amount of data and processing.)