Bacon cipher

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The Bacon cipher is a steganography process that goes back to Francis Bacon . A five-digit code is assigned to each letter of the original text:

Letter code Letter code Letter code
A. aaaaa I, J abaaa R. baaaa
B. aaaab K abaab S. baaab
C. aaaba L. ababa T baaba
D. aaabb M. fig U, V baabb
E. aabaa N abbaa W. babaa
F. aabab O fig X babab
G aabba P abbba Y babba
H aabbb Q fig Z babbb

The word "Wikipedia" would be encoded as:
"babaa abaaa abaab abaaa abbba aabaa aaabb abaaa aaaaa".

This coding is now hidden in a text. There are several procedures for this:

  • Two different fonts can be used for the individual letters of a text. A font stands for the letter a, b and the other for the letter " D i e s is t a f as t u n auff AELL owned N achri ch t, o the not?". Francis Bacon has developed a handwriting made up of 21 characters in which there are two different forms for each uppercase and lowercase letter. This is the original form of the Bacon cipher.
  • Instead of using different fonts, lowercase letters can be used for "a" and uppercase letters for "b": "THIS IS A FASTS OF UNNOTICIAL MESSAGE, OR IS IT?".
  • A sentence is formed in which the first letters of the words stand for the letters "a" and "b". If a word begins with one of the letters AM, it stands for "a". Words that begin with NZ represent a "b". Example: " W inter A m N ordpol i st m eist g . Facilitated N for a m A t the beginning i st e s s . Eltsam A about d ann w ill m at s I d aran g . Ewöhnen G num k old s ind W ater u nd e is. D he e isbär s chwimmt i m m EER. H elp i st m eist n maybe v orhanden. A over n ie a ufgeben. I ch b in d och e rst e inen K ilometer e away . "
  • If you don't want to disguise the transmission of a secret message, the Bacon cipher can also be used for encryption. For each "a" one randomly selects one of the letters AM, for each "b" one of the letters NZ: "SDUAG MTBAH JQCLN EZEBI AVOXK MATHE BACON BXDFH DKCEI".
  • Another possibility is that 'a' and 'b' stand for one- and two-syllable words, respectively. A problem here is that two-syllable words occur less often than monosyllabic ones, which on the one hand makes the construction of the text difficult and on the other hand the application could be verifiable. If you determine, unlike in the linked example, that more than one syllable (including three, four, etc. syllable words) count as 'b', you can present "Wikipedia" with this seemingly harmless SMS among friends of yours: "Although I don't have the time tomorrow to visit you, I'm sure we'll meet during the vacation time, so that there is finally time to play cards like in the year before the new shift schedule. Then there is sure to be time for a drink Beer."

analysis

If the procedure is known, the text can be easily deciphered. If you use a separate word for each letter "a" or "b", the difficulty lies in creating an inconspicuous text that does not attract attention through a conspicuous sentence structure or unusual words. The analysis becomes significantly more difficult if the text is encrypted first, because - with good cryptosystems - it is then an almost evenly distributed, random character string that every text contains, even if it does not contain any steganography. Thus, every text becomes a potential steganogram, the content of which is encrypted, and detection is hardly possible.

Bacon's cipher is one of the first applications of the dual system in Europe.

Bacon and Shakespeare

It has been suggested that the plays that are attributed to William Shakespeare were actually written by Bacon, and that these plays contain steganographic messages. The researchers Ignatius L. Donnelly and Elizabeth Wells Gallup tried to find such steganograms by means of a bar analysis of the early printed editions of Shakespeare's works.

The American cryptologists William and Elizebeth Friedman refuted the claim that the works of Shakespeare contain steganographed cryptograms, which indicate the authorship of Bacon or any other candidate, in their publication The Shakespeare Ciphers Examined (1957).

Individual evidence

  1. ^ Helen Fouché Gaines : Cryptanalysis. A Study of Ciphers and Their Solutions. Dover, New York NY 1989, ISBN 0-486-20097-3 , p. 6.
  2. ↑ sdtp.de.tl ( Memento from September 25, 2015 in the Internet Archive )