Why did they say Beale Cipher

Question

In the Film Imitation Game, Commander Denniston has found news of a Soviet Spy working at Bletchley Park, which they've managed to track back to Hut 8, the room in which Alan Turing works, so he has the guards search Turing's desk, thinking that he is the spy, but they find nothing. When Turing asks what this is about:

Denniston hands Alan a TELEGRAM — it’s a LONG STRING OF LETTERS, running down the entire page.

ALAN TURING: This is a Beale Cypher. It’s encrypted with a key phrase, from a book or a poem or...

And then later in the film:

HUGH ALEXANDER: Denniston gave me the Beale Cypher. And guess what? I broke it. “Ask and it shall be given you; seek and ye shall find.” Matthew 7:7. That was the key. Far too simple for you. Pity Denniston disagrees.

Why do they refer to a Beale Cipher? The Beale Cipher or Beale Papers are a specific set of coded messages reportedly created by Thomas Beale.

While it is always possible, even likely, that both accomplished mathematicians would have heard of the Beale Papers, what they are referring to seems more like a Vigenere Cipher. This is definitely something that Alan and Hugh would know of and would be unlikely to use the incorrect name.

I know it's unlikely that anyone would know the 100% truth as to what was said at the time in real life so...

Is there a known reason they called it a Beale Cipher in the film? Was it a small joke or easter egg? Or is there a mysterious Cipher called a Beale Cipher I'm not aware of?

Answer 1

Because movies are notoriously bad when it comes to facts:

Let me mention two small but interesting miscues among many inaccuracies. After Turing’s arrest, a newspaper article sports the headline, “Cambridge Professor Convicted of Indecent Acts.” Actually, Turing was a professor at the University of Manchester.

There was a Soviet spy at Bletchley Park, and the movie references him. However, the film shows the spy unmasked because he used an insecure “Beale cipher” when passing secrets to the Soviets. In reality, the Beale cipher refers to a specific encrypted message from early 18th century Virginia that is reputed to hide the location of a fabulous buried treasure; it is not a particular kind of cipher.

Answer 2

Well I found a « reference » describing something that is called a Baele cipher.

https://en.m.wikibooks.org/wiki/Cryptography/Beale_cipher

It’s consistent with the Wikipedia article on the Baele papers https://en.m.wikipedia.org/wiki/Beale_ciphers

It describes how the 2nd cipher text was encrypted using a variation of a book cipher.

https://en.m.wikipedia.org/wiki/Book_cipher

From what I understand, a book cipher uses an agreed upon version of a book as a key. Let’s call it the key text. The cipher text is a list of numbers to be interpreted as locations of words in the key text. So to decipher the text, you just look up the words in the key text. And the secret is to know what is the exact key text.

So typically a specific edition of the bible could be the key for a book cipher.

For his 2nd paper, Baele used a variation of this cipher using the Declaration of Independence as key text. The cipher numbers point towards words of the key text, but you have to take only the first letter of the pointed word, which makes one letter of the clear text.

So there’s is a « Baele cipher » but the key to such a cipher needs to be a long text, like the Bible. Not just one sentence of it.

The movie indeed made a mishmash of book cipher, Baele cipher and bible.