Homophonic Substitution Cipher: From Defeating Frequency Analysis to the Zodiac Killer
A comprehensive guide to homophonic substitution ciphers covering their invention by Renaissance cryptographers, how they defeat frequency analysis, the Great Cipher of Louis XIV, the Zodiac Killer's famous ciphers (Z408 solved in 1969, Z340 cracked in 2020 with AI assistance), and practical techniques for constructing and breaking homophonic codes.