adfgvx cipher aden affine cipher al-kindi alberti cipher algorithm alphabet american civil war arab atbash aulus gellius autokey cipher bernardo provenzano bifid cipher block cipher book cipher brute force attack ciphertext-only attack confederate states of america cryptanalysis cryptogram cryptographic hash function cryptographically secure pseudorandom number generator cryptography david kahn digital object identifier encryption four-square cipher frequency analysis great cipher hill cipher history of cryptography index of coincidence julius caesar kasiski examination keyword cipher literacy mafia mathematical association of america message authentication code mezuzah modular arithmetic modulo operation names of god in judaism nihilist cipher one-time pad permutation cipher pigpen cipher plaintext playfair cipher polyalphabetic cipher polybius square public-key cryptography rail fence cipher reihenschieber reservehandverfahren running key cipher scytale secret decoder ring sicily smithy code steganography straddling checkerboard stream cipher substitution cipher suetonius symmetric-key algorithm tabula recta tap code the register the times topics in cryptography transposition cipher trifid cipher two-square cipher unicity distance vic cipher