double english_freq[ALPHABET_SIZE] = {8.2, 1.5, 2.8, 4.3, 13.0, 2.2, 2.0, 6.1, 7.0, 0.2, 0.8, 4.0, 2.4, 6.7, 7.5, 1.9, 0.1, 6.0, 6.3, 9.1, 2.8, 1.0, ...

The monoalphabetic substitution cipher replaces each letter in the plaintext with a corresponding letter from a substitution key. The key is a permutation of the alphabet, where each letter maps ...