Cipher Identifier

Scores a text against 38 possibilities — encodings (Morse, binary, hex, Base64/32/58/85, JWT, zero-width), classical ciphers from Caesar to ADFGVX and Enigma, and hash formats from MD5 to bcrypt and Argon2 — by character set, length, index of coincidence and letter statistics, then auto-solves 11 cipher types and opens the matching tool. English has an index of coincidence near 0.067, random letters 0.038; William Friedman introduced the measure in 1922.

• William F. Friedman, The Index of Coincidence and Its Applications in Cryptography, Riverbank Publication No. 22 (Geneva, Illinois: Riverbank Laboratories, 1922)
• David Kahn, The Codebreakers: The Story of Secret Writing (New York: Macmillan, 1967)