A Caesar cipher is an encryption scheme based on cyclic permutations of the alphabet, with the i-th letter of the alphabet replaced by the (i + n)-th letter of the alphabet. For example, in a Caesar cipher with a shift of 4, “Caesar” would be encrypted as “Geiwev.”

a. Give three heuristics that might be used for solving Caesar ciphers.

b. In a simple substitution cipher, each letter is replaced by another letter under some arbitrary one-to-one mapping. Which of the heuristics proposed for the Caesar cipher may be used to solve substitution ciphers? Explain. (Thanks to Don Morrison for this problem.)