Le chiffre de Beale / The Beale cipher


ENG : cryptography, Beale Papers, Beale Cipher, book cipher, treasure cipher

FR : cryptographie, chiffre de Beale, papiers de Beale, chiffre dictionnaire, trésor de Beale


The Beale cipher [WARD1885] is a famous irresolute code since more than one century. It is a dictionary code, [LEIGHTON1984] i.e. the key which makes it possible to decipher the figure is provided by a text. It is composed of 3 papers, which I will call C1, C2 and C3. Only C2 was solved: the key text is the Declaration of Independence of the United States (1776).
I wrote a program in language C which attacks the figure by systematic test with a list of key texts. This analysis is original for two reasons; firstly the texts key come from Internet and largely from the Gutenberg Project, which provides a great quantity of free texts; secondly an algorithm makes it possible to detect the clear words in a deciphered text, to replace the aptitude of a human reader to discriminate between a random text and a comprehensible text. Thus C2, which comprises faults of retranscription, is understood to approximately 60% by the algorithm; in comparison a random text is understood to 33% and one comprehensible text with 90%. The totality of the process reproduces the mechanism of research of a person wanting to attack the code by test with all the texts at its disposal and while controlling that the text obtained has a direction. This tiresome research which took months and months in 1900 takes a few hours today.
For the moment, more than 8000 complete texts of English language were tested on C1 and C3, without positive results. It very probable that the key text is not a text running or is published. In spite of the strong presumptions to the Beale cipher is a hoax [KRUH1982] , this research is justified by work of Carl Hammer [HAMMER1971] which concludes that the figures C1 and C3 have all the characteristics of a true cipher.

More details in french.

"Signature Simulation and Certain Cryptographic Codes"
Hammer, Communications of the ACM, 14 (1), January 1971, pp. 3-14.
Washington : Computer Services UNIVAC.

A basic probe of the beale cipher as a bamboozlement - PART I.
Louis Kruh, Cryptologia, 6 (4) 378-382 (1982)

The history of book ciphers
Albert C.Leighton and Stephen M. Matyas

THE Beale Papers,
AND Which Has Never Been Recovered.
LYNCHBURG: Virginian Book and Job Print, 1885.
Entered according to act of Congress, in the year 1885, by J. B. Ward,
in the Office of the Librarian of Congress, at Washington.

Ayrinhac Simon - 2007

Up - Back