Cipher | Intelligence 101

Welcome back Intel Analysts –

This week I stumbled across a little known photograph that took me down a rabbit hole of codes, ciphers and cryptic messages –

Read on to find the hidden code in this image.

For those following me on twitter or FB, I asked the importance of this 1918 image?

View full image here

Turns out, this photo contains a hidden message – a hidden code in plain sight!

Cool huh?

For context, the photo is of U.S. Army code breakers trained by William Friedman and his wife Elizebeth during WW1.

William and Elizebeth Friedman had astonishing careers in cryptanalysis, and William is known today as the father of modern American cryptology (Source).

If you look closely, you’ll note soldiers are either facing forward towards the camera, while others are facing to the side –

Using the Baconian Cipher (or Bacon’s Cipher) the soldiers can be divided into groups of 5, and the secret message decoded using the A/B system.

Before I give away the secret message however, let’s take a quick lesson into how codes, ciphers and cryptography work.

Codes – Codes are used to translate whole words into other words, phrases or numbers.

Ciphers – Change the individual characters into numbers, alternative letters or symbols.

Cryptography – Is the art / science of writing and deciphering codes.

Cryptanalysis – the term used for the study of methods for obtaining the meaning of encrypted information without access to the key normally required to do so. I.e. the study of how to crack encryption algorithms or their implementations.

How Ciphers Work?

Ciphers have three parts,

the plain text – the letters or words revealed after the cipher is decoded
the cover-text – the message used to conceal the plain text
the key – used to decode the cover-text to reveal the plain text.

Famous Ciphers

The most famous of these is the enigma machine – which encoded German communications during WWII.

Bacon’s A/B System

Within the Baconian Cipher each letter of the plain text is replaced by a group of five ‘A’s, or ‘B’s – according to the key below:

In our context, Friedman employed the Baconian cipher with soldiers facing towards the camera, and others facing away.

The crucial part about Bacon’s system is that the a’s, and b’s do not actually need to be represented by the letters explicitly.

In his system, the a’s and b’s could be divided into any two distinct classes – such as fruit (e.g. apples & oranges) or open and shut windows in a photograph.

The secret message, hidden in plain sight was the famous Baconian motto “Knowledge is power,” but there were insufficient people to complete the ‘R’ (and apparently one soldier in the ‘W’ group looked the wrong way) –

William Friedman was particularly fond of this photo and kept this picture on his desk at home and in his office.

Bacon Binary System (Advanced) –

If you check out the Bacon system on Wikipedia it explains about using a binary set of numbers rather than the A/B system as described –

An advanced method of this cipher involves converting your coded message into binary code (1’s and 0’s) and overlaying it with a corresponding block of cover text.

Secret Message: “BACON TAUGHT ME HOW TO THINK”

Becomes:

00001 00000 00010 01110 01101 10011 00000 10100

00110 00111 10011 01100 00100 00111 01110 10110

10011 01110 10011 00111 01000 01101 01010.

Which can be hidden in a sentence of corresponding letters (23 blocks x 5 binary numbers = 115 characters).

I found a corresponding sentence from a random Wikipedia page on Selective Hearing:

“Selective auditory attention is a type of selective attention where ones auditory directed at things people are interested in hearing.” (115 characters)

Which looks like this when it’s broken up the text into blocks of 5 (to match the binary code):

And then overlay the blocks of text with the binary blocks:

00001	00000	00010	01110	01101	10011	00000	10100
Selec	tivea	udito	ryatt	entio	nisat	ypeo	fsele
00110	00111	10011	0110	00100	00111	01110	10110
Ctive	Atten	Tionw	Hereo	Nesau	Ditor	Ydire	cteda
10011	01110	10011	00111	01000	01101	01010
Tthin	Gspeo	Plear	Eninte	Reste	Dinhe	aring

And finally, put it back together making the 1’s boldface within the sentence.

The cover-text is written as:

Selective auditory attention is a type of selective attention where ones auditory directed at things people are interested in hearing.

(Use the Bacon binary method to decipher the plain-text code from the cover-text)

Other Ciphers and Ways to Code Messages

Replacing letters with numbers

or a simple cipher like -e.g. A=1, B=2, etc,

The Pigpen Code

Can you decipher this code?

or perhaps most famous;

Morse Code

International Morse Code, used for communicating via electronic communication, with lights or sound – Morse code is probably the most well-known form of code / cipher.

The length of a dot is one unit, whereas the dash represents three units.
The space between parts of the same letter is one unit.
The space between letters is three units.
The space between words is seven units.

Can you decipher: – .. – / — ..- … – / -… . / …. .- .-. -.. / .-. . — . — -… . .-. .. -. –. / .- .-.. .-.. / – …. . … . / -.. .. – … / .- -. -.. / -.. .- …. …

Want More?

For more on Wiliam Friedman’s Famous Photograph (and analysis) by the GC Marshall Foundation see the below video (5 mins)

Activity

Ok, you’ve got the brief –

You’re now an expert in codes so decipher the Pigpen code above – post in the comments once complete.

Happy code-breaking.