How to Solve the Playfair Cipher

These are the ciphers that actually turn up inside treasure hunts, where the encoding is one layer of a puzzle rather than the whole puzzle. They tend to hide the message rather than merely scramble it.

How to recognise it

Look at the structure before you look at the letters. Text that groups into fives, pairs that never repeat a letter, a sentence that reads perfectly but sits oddly — the shape is the clue.

Playfair Letters travel in pairs across a 5×5 square. Same row, step right; same column, step down; otherwise swap corners. I and J share a cell.

The square

Playfair is unsolvable without its square, so it is part of the puzzle rather than a hint — every daily cipher of this kind prints one alongside the message.

A	N	V	I	L
B	C	D	E	F
G	H	K	M	O
P	Q	R	S	T
U	W	X	Y	Z

A worked example

This is the kind of cipher that turns up inside real treasure hunts, where the encoding is a layer rather than the whole puzzle. This one is Playfair. The key: keyword ANVIL. Letters travel in pairs across a 5×5 square. Same row, step right; same column, step down; otherwise swap corners. I and J share a cell. Apply the key to the first three letters and they resolve to T R E. The answer was TREASURE MAP.

Working one out from scratch

Decide what the carrier is first: which part of what you are looking at is the message, and which part is packaging. Everything else follows from getting that right.