It's about Cryptography and please write the program in Java.

This file contains ASCII encoded English characters with capital letters only and no punctuation or spaces. The ciphertext was generated from plaintext using the Hill cipher with a block size of two and arithmetic over ₂₆". In this question, you are going to input the file and implement a ciphertext only attack to derive the plaintext by determining the decryption key.

Take the following approach to breaking the cipher.

(a) Write a program to calculate and store the frequencies of all possible 2-character ciphertext blocks. Use common digrams (two-character combinations) to guess at the mapping between likely plaintext blocks and ciphertext blocks. The most likely digrams in English are th, he, in, er, and an in that order. You do not need to know the frequencies of these digrams precisely in general English text, and, of course, in the data you have, the frequencies and relative order may be a little different.

(b) Calculate (by hand if you want) the decryption key for the system following your thoughts from (a).

(c) Now write a program to decrypt the entire ciphertext and identify the source of the plaintext.

Ciphertext:

FUGOMRPKWODRDTJHDTHPQTJDADFKLZDTYFWCDLJD ALRPNNQVPHZDRFMIPPSXWOSWDFUXELKMMGVOGBOD EACSZJJDNDZROFMRAHAERPEAFJTNCZXPUDKQDITN YPFKNFBKOODBZPECFKWYXPGBEACFUQNQECCXSTGC ZDCKGBZRQVFKBKVRIIVRBKZJECUVANJQVRBKQGZR BKDLECNSMGULBKVRIIVRGBFKKLBRGBANKOMGLCEC IZRPNNGJQZDTUVKLRFECDSSFSXKLCAHLTRWUCOFG LNSXWOBKSYKLKDXPNLWUELQEFVQMQEVSJVQMUYKL LDHVXPBKCKCZMEFGDTNFGENYYIDOZDBHOSSCGPCK UVODBKIUFGNFYKQVYMJQYVBXWRPQKELWGBQTWYFJ BHXRCSQEBHBKDTSYCSQBMRPPZPNFBKUQHCMGVUZJ