Feedback | Home
A type of cipher where a book or other widely available text is used as a key, and the message is encoded as a series of numbers which are indexes into the text. Indexes may be single (word or letter counts in the entire text) or multiple (indexing first by page, then by word, or first by word, then by letter, etc.) This is sometimes called a Beale cipher, in reference to a famous one which used the U.S. Declaration of Independence as a key.
MIT Mystery Hunt 2012 1207 1370