Types of Ciphers: Caesar, Substitution, and More

A cipher is a method of disguising a message by transforming its letters according to a rule, and humans have invented dozens of them over thousands of years. Cryptogram puzzles use one particular kind, but it helps to see where it fits in the wider family of ciphers and codes. This guide walks through the main types of ciphers, from the simple Caesar shift to the trickier Vigenère, explaining how each works and which ones make good puzzles. If you just want to start cracking codes, our cryptograms use the classic substitution cipher across five levels.

Two big families: substitution and transposition

Almost every classical cipher belongs to one of two families:

• Substitution ciphers replace each letter with a different letter or symbol, while keeping the letters in their original positions. The message structure (word lengths, letter positions) stays intact.
• Transposition ciphers keep the original letters but rearrange their order, scrambling positions rather than identities.

Cryptograms are substitution ciphers, which is why word lengths and patterns survive to help you solve them. Here are the most important types.

The Caesar cipher (shift cipher)

The simplest substitution cipher, named for Julius Caesar. You shift every letter a fixed number of places down the alphabet. With a shift of 3, A becomes D and "HELLO" becomes "KHOOR." There are only 25 possible shifts, so a Caesar cipher is trivial to break, you can just try them all. It's a great introduction to the idea of enciphering and a favorite for kids' secret messages.

The simple substitution cipher

This is the cryptogram cipher. Instead of a fixed shift, every letter maps to any other letter, so the 26 letters can be scrambled in any order. That gives an enormous number of possible keys (26 factorial, over 400 septillion), which makes brute force useless. But because the cipher preserves English letter frequencies and word patterns, it's still solvable by frequency analysis, which is exactly what you do in a cryptogram. There's a full breakdown in what is a substitution cipher.

The Atbash cipher

An ancient substitution cipher, originally used for the Hebrew alphabet, that reverses it: A becomes Z, B becomes Y, C becomes X, and so on. It's a fixed mapping with no key to remember, which makes it elegant but, like Caesar, easy to crack once you recognize it.

The Vigenère cipher

A famous step up in strength. The Vigenère cipher is polyalphabetic: it uses a keyword to apply different shifts to different letters, so the same plaintext letter can encode to different letters in different places. That smooths out the letter frequencies and defeats simple frequency analysis, which is why it was considered unbreakable for centuries (it earned the nickname "le chiffre indéchiffrable"). It's far harder to solve than a cryptogram and generally needs the keyword length to be worked out first.

The Pigpen cipher

A substitution cipher that swaps letters for symbols instead of other letters, using a grid of lines and dots. Each letter sits in a section of a tic-tac-toe-style grid, and its symbol is the shape around it. It looks mysterious but is just a substitution cipher in disguise, so the same solving logic applies once you map the symbols.

Transposition ciphers

Rather than changing letters, these rearrange them. In a rail fence cipher, you write the message in a zigzag across several "rails" and read it off row by row. In a columnar transposition, you write the text into a grid and read the columns in a keyword-determined order. Because every original letter is still present, transposition ciphers are vulnerable to anagram-style analysis rather than frequency analysis.

Ciphers vs codes

People use "code" and "cipher" loosely, but there's a technical difference. A cipher works at the level of individual letters (substituting or rearranging them), while a code replaces whole words or phrases with other words, numbers, or symbols (like a codebook that turns "ATTACK AT DAWN" into a single code group). Cryptograms are ciphers, not codes, you're decoding letter by letter.

Which ciphers make good puzzles?

The simple substitution cipher is the sweet spot for puzzles, and that's no accident. It's complex enough that the answer isn't obvious (unlike a Caesar shift you could brute-force in seconds), yet it preserves enough English structure that a determined solver can always crack it with logic. That balance of challenge and fairness is why cryptograms have endured as a puzzle for generations.

Want to try the puzzle-friendly cipher yourself? Our cryptograms are simple substitution ciphers hiding famous quotes, and the solving guide teaches you to crack them. For the math behind why they're solvable, see letter frequency analysis.