Answer question completely and carefully with full working out for a thumbs up, it is on cryptography.

Exercise 2: a) Eve is given a ciphertext 'NBYYUAFYZFCYMUNGCXHCABN' and the information that the plaintext is in English and encrypted with the 26-character shift cipher. Apply frequency analysis to the ciphertext and find both the key and the decrypted plaintext. b) Eve is given a ciphertext encrypted with the 26-character Vigenre cipher 'MWAYSOKZRWBQZMBLNKAIEOOTVWAYFMPPRNGOYWANHFBWEPVBUBNPSOKVGEBR' and the information that the plaintext is in English. Find the most common bigram in the ciphertext, use it to apply the Kasiski test, and estimate the length of the key k