Editing Bacon's cipher

{{short description|Steganography method}}
[[File:FBacon alfa1.jpg|thumb|Image of Bacon's cipher.]]
'''Bacon's cipher''' or the '''Baconian cipher''' is a method of [[steganography|steganographic]] message encoding devised by [[Francis Bacon]] in 1605.<ref name="Bacon_1605">{{cite book |author-last=Bacon |author-first=Francis |author-link=Francis Bacon |title=The Proficience and Advancement of Learning Divine and Humane |year=1605}}</ref><ref name="Bacon_1640">{{cite book |author-last=Bacon |author-first=Francis |author-link=Francis Bacon |title=Of the Advancement and Proficience of Learning |year=1640 |translator-first=Gilbert |translator-last=Wats |publisher=Oxford University |pages=257–271}}</ref><ref name="Dupuy">{{cite web |author-last=Dupuy, Jr. |author-first=Paul J. |work=An Authorship Analysis – Francis Bacon as Shake-speare |publisher=Shake-n-Bacon |orig-year=May 1996 |title=The Advancement of Learning |volume=6 |location=London |at=Chapter 1 |url=http://home.hiwaay.net/~paul/bacon/advancement/book6ch1.html |access-date=2017-03-18 |url-status=live |archive-url=https://web.archive.org/web/20170318232428/http://home.hiwaay.net/~paul/bacon/advancement/book6ch1.html |archive-date=2017-03-18}}</ref> In steganography, a message is concealed in the presentation of text, rather than its content. Baconian ciphers are categorized as both a [[Substitution cipher|substitution]] cipher (in plain code) and a [[Null cipher|concealment]] cipher (using the two typefaces).

==Cipher details ==
To encode a message, each letter of the [[plaintext]] is replaced by a group of five of the letters 'A' or 'B'. This replacement is a 5-bit [[binary number|binary]] encoding and is done according to the alphabet of the Baconian cipher (from the Latin Alphabet), shown below: 
{|
|
{| class="wikitable"
|-
! Letter !! Code !! Binary
|-
| A || aaaaa || 00000
|-
| B || aaaab || 00001
|-
| C || aaaba || 00010
|-
| D || aaabb || 00011
|-
| E || aabaa || 00100
|-
| F || aabab || 00101
|-
| G || aabba || 00110
|-
| H || aabbb || 00111
|-
| I, J|| abaaa || 01000
|-
| K || abaab || 01001
|-
| L || ababa || 01010
|-
| M || ababb || 01011
|}
|
{| class="wikitable"
|-
! Letter !! Code !! Binary
|-
| N || abbaa || 01100
|-
| O || abbab || 01101
|-
| P || abbba || 01110
|-
| Q || abbbb || 01111
|-
| R || baaaa || 10000
|-
| S || baaab || 10001
|-
| T || baaba || 10010
|-
| U, V|| baabb || 10011
|-
| W || babaa || 10100
|-
| X || babab || 10101
|-
| Y || babba || 10110
|-
| Z || babbb || 10111
|}
|}

A second version of Bacon's cipher uses a unique code for each letter. In other words, ''I'', ''J'', ''U'' and ''V'' each have their own pattern in this variant:

{|
|
{| class="wikitable"
|-
! Letter !! Code !! Binary
|-
| A || aaaaa || 00000
|-
| B || aaaab || 00001
|-
| C || aaaba || 00010
|-
| D || aaabb || 00011
|-
| E || aabaa || 00100
|-
| F || aabab || 00101
|-
| G || aabba || 00110
|-
| H || aabbb || 00111
|-
| I || abaaa || 01000
|-
| J || abaab || 01001
|-
| K || ababa || 01010
|-
| L || ababb || 01011
|-
| M || abbaa || 01100
|}
|
{| class="wikitable"
|-
! Letter !! Code !! Binary
|-
| N || abbab || 01101
|-
| O || abbba || 01110
|-
| P || abbbb || 01111
|-
| Q || baaaa || 10000
|-
| R || baaab || 10001
|-
| S || baaba || 10010
|-
| T || baabb || 10011
|-
| U || babaa || 10100
|-
| V || babab || 10101
|-
| W || babba || 10110
|-
| X || babbb || 10111
|-
| Y || bbaaa || 11000
|-
| Z || bbaab || 11001
|}
|}

The writer must make use of two different [[typeface]]s for this cipher. After preparing a false message with the same number of letters as all of the ''As'' and ''Bs'' in the real, secret message, two typefaces are chosen, one to represent ''As'' and the other ''Bs''. Then each letter of the false message must be presented in the appropriate typeface, according to whether it stands for an ''A'' or a ''B''.<ref>Helen Fouché Gaines, ''Cryptanalysis: a Study of Ciphers and Their Solutions'' (1989), page 6]</ref>

To decode the message, the reverse method is applied. Each "typeface 1" letter in the false message is replaced with an ''A'' and each "typeface 2" letter is replaced with a ''B''. The Baconian alphabet is then used to recover the original message.

Any method of writing the message that allows two distinct representations for each character can be used for the Bacon Cipher.
Bacon himself prepared a ''Biliteral Alphabet''<ref>Biliteral can mean: "written in two different scripts", ''Oxford English Dictionary''</ref> for handwritten capital and small letters with each having two alternative forms, one to be used as ''A'' and the other as ''B''. This was published as an illustrated plate in his ''De Augmentis Scientiarum'' (The Advancement of Learning).

Because any message of the right length can be used to carry the encoding, the secret message is effectively hidden in plain sight. The false message can be on any topic and thus can distract a person seeking to find the real message.

==Baconian cipher example==
The word 'steganography', encoded with quotation marks, where standard text represents "typeface 1" and text in boldface represents "typeface 2":

{{quote|'''T'''o en'''co'''de '''a''' mes'''s'''age e'''ac'''h letter '''of''' the '''pl'''a'''i'''nt'''ex'''t '''i'''s replaced b'''y a g'''rou'''p of f'''i'''ve''' o'''f t'''he l'''et'''te'''rs 'A' or 'B'.'''|author=|title=|source=}}

The pattern of standard and boldface letters is:

{{quote|ba aabbaa b aaabaaa abba aaaaaa bb aaa bbabaabba ba aaaaaaaa ab b baaab bb babb ab baa abbaabb 'b' bb 'b'.|author=|title=|source=}}

This decodes in groups of five as

{{quote|baaab(S) baaba(T) aabaa(E) aabba(G) aaaaa(A) abbaa(N) abbab(O) aabba(G) baaaa(R) aaaaa(A) abbba(P) aabbb(H) babba(Y) bbaaa bbaab bbbbb|author=|title=|source=}}

where the last three groups, being unintelligible, are assumed not to form part of the message.

==Bacon and Shakespeare==

Some proponents of the [[Baconian theory of Shakespeare authorship]], such as [[Elizabeth Wells Gallup]], have claimed that Bacon used the cipher to encode messages revealing his authorship in the [[First Folio]]. However, American [[Cryptography|cryptologists]] [[William F. Friedman|William]] and [[Elizebeth Friedman]] refuted the claims that the works of Shakespeare contain hidden ciphers that disclose Bacon's or any other candidate's secret authorship in their ''The Shakespeare Ciphers Examined'' (1957). Typographical analysis of the First Folio shows that a large number of typefaces were used, instead of the two required for the cipher, and that printing practices of the time would have made it impossible to transmit a message accurately.<ref>{{cite book|last1=Kahn|first1=David|title=The Code-breakers|date=1996|publisher=Scribner|location=New York|isbn=0-684-83130-9|pages=882–888|edition=2nd}}</ref>

The [[William F. Friedman|Friedmans]]' tombstone included a message in Bacon's cipher not spotted for many years.<ref>{{cite news|last1=Dunin|first1=Elonka|title=Cipher on the William and Elizebeth Friedman tombstone at Arlington National Cemetery is solved|url=http://elonka.com/friedman/FriedmanTombstone.pdf|work=Elonka.com|date=17 April 2017}}</ref>

==See also==
*[[Baudot code|Baudot]], a set of 5-bit codes for the English alphabet, used world-wide for teleprinter communications during most of the 20th century.
*[[Null cipher|Null Cipher]], a related cipher.

==References==
{{Reflist}}

==Further reading==
* [[William Friedman]] and [[Elizebeth Friedman]], ''The Shakespearean Ciphers Examined'', [[Cambridge University Press]], 1957

==External links==
*[http://www.cabinetmagazine.org/issues/40/sherman.php How to Make Anything Signify Anything]
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