Tools / Game Room · Cipher Tool
📖 Porlock's Book Cipher
Encode and decode book ciphers like the one Fred Porlock sent Holmes in The Valley of Fear, plus the hidden-word cipher of "The Gloria Scott" and the candle code of "The Red Circle".
1 · Choose the book
Sender and receiver must share the same text. Every word in it gets a number, counting from 1.
2 · Encode a message
3 · Decode numbers
Reads as:
The key text
Highlighted words are the ones your cipher points to. Click any word to see its number.
Step 1 of 7
A letter from Porlock
WHITAKER'S ALMANACK1887534
An illustration: the story never prints the almanac page, so the words around Porlock's are invented filler. Only the numbered words (and the 1888 edition's "Mahratta", "Government" and "pig's-bristles") come from Conan Doyle.
Decode a hidden-word message
In "The Gloria Scott", a harmless note about game birds hides a warning: read every third word, starting with the first. Paste any text and choose the interval.
Hidden message:
Try every interval, as Holmes did
Holmes tried the note backwards, then every other word, before every third word gave up its secret. Here are the readings for the text above.
Hide your own message
Write the warning; the Bureau pads it with filler so every Nth word carries it. Then polish the filler by hand until it reads like an ordinary note.
The candle code
In "The Adventure of the Red Circle", Gennaro signals to Emilia from a window across the street: one flash of the candle for A, two for B, twenty for T. Holmes and Watson count along and read ATTENTA (beware), then PERICOLO (danger).
Decode a count
Reads as: