A cryptogram is a type of word puzzle popularly printed in some newspapers and magazines. A short piece of text is given, encrypted with a simple substitution cipher in which each letter is replaced by a different letter. To solve the puzzle, one must recover the plaintext; this is usually done by frequency analysis and by recognizing letter patterns in words. The Cryptogram is also the name of the periodic publication of the American Cryptogram Association (ACA), which contains a large number of cryptographic puzzles.
The word "Cryptogram" is sometimes used in cryptography in a more general sense, as a synonym for "ciphertext".
Bruce Schneier's monthly newsletter on computer security and cryptography is called the Crypto-Gram.
| Classical cryptography |
| Ciphers: ADFGVX | Affine | Atbash | Autokey | Bifid | Book | Caesar | Permutation | Playfair | Polyalphabetic | Running key | Substitution | Transposition | Vigenère |
| Cryptanalysis: Frequency analysis | Index of coincidence Misc: Cryptogram | Polybius square | Scytale | Straddling checkerboard | Tabula recta |