Jason September 3, 2008 1:54 PM

Apparently this practice was common with early Methodists. They kept daily journals with personal information encrypted, to keep the private things private.

Part of the Methodist ‘method’ was exchanging journals with others to give one another spiritual counsel. Every Methodist would have to be able to read the ciphertext in the others’ journals–a ‘shared secret’ technique.

In a manner of speaking, the early Methodists developed a weak form of symmetric-key cryptography. I don’t know if they drew much on a prior art, but it isn’t bad for the 18th century!

Milan September 3, 2008 2:38 PM

Perhaps the most interesting example of a ‘ciphered’ diary is that of Samuel Peyps.

While it was technically written in shorthand, it nonetheless took The Reverend John Smith three years to translate the diaries into standard English.

Caleb Jones September 3, 2008 6:38 PM

When I read that title I thought to myself:

while (alive == true) {
 String dailyEntry = “”;
 dailyEntry += doMorningRoutine();
 dailyEntry += commute(TO_WORK);
 dailyEntry += work();
 dailyEntry += commute(FROM_WORK);
 dailyEntry += doEveningRoutine();


James Fulford September 4, 2008 1:16 AM

Here’s a description of Stephen Maturin’s diary habits, from THE REVERSE OF THE MEDAL, set during the Napoleonic Wars:

“For many years Stephen Maturin had kept a diary: but diary-writing was not really a suitable habit in an intelligence-agent, and although the code in which it was written had never yet been broken, the book had proved an embarrassment when he was taken prisoner by the Americans. [In the War of 1812, in an earlier book]

Yet just as he had returned to opium when Diana disappeared from his life, so the returning urge to record, to communicate at least with his future self, overcame his scruples now and he indulged himself in the purchase of a comfortable green-bound quarto of blank pages that opened really flat; in this he confined himself to observations on medicine, natural philosophy and personal affairs, so that if by any remote chance the book should fall into an enemy’s hands it would compromise no other agent or network but would rather tend to show that the writer had no concern with such matters. Yet what he did write was perfectly candid and sincere, being intended for his own eye alone; and it was written in the Catalan of his youth, as familiar to him as English and more so than the Irish of his childhood.”

bob September 4, 2008 6:55 AM

I dont understand the British WWII officer piece. According to the article if the Japanese had caught him writing a diary they would have beaten/killed him. But apparently it was OK for him to painstakingly write down page after page of meaningless scribbles every day?

@Peter S: Did she say anything about decrypting them?

bob September 4, 2008 7:03 AM

@Caleb Jones: Shouldn’t you “terminate” the code after the while loop with something like writeDailyJournalEntry(textObituary); ?

TSK September 4, 2008 11:33 AM

A personal question to Bruce:

The officers diary was cracked by a “normal” mathematician, not a cryptoanalysist.
Why are such problems like old diaries, important documents, unknown scripts in languages not almost always transferred to cryptoanalysts, at least to ask for help ?
I got the impression that e.g. in “The Code Book” much more amateurs are cracking such codes than profs.

What is the reason for that ?

B. September 4, 2008 12:36 PM

It seems to me, TSK, that cryptanalysists as a whole in modern times are concerned cheifly with breaking strong encryption; easy or non-standard encryption/concealment does not interest them, but it does interest amateurs.

GCU Prosthetic Conscience September 4, 2008 1:51 PM

It seems we now live in an age where there’s no point to a diary written in cipher by hand, since even the most effective cipher you could use would be trivial to break. To use strong encryption, you’d have to keep your diary on a computer, which takes half the fun out of it.

Davi Ottenheimer September 4, 2008 4:03 PM

@ GCU Prosthetic Conscience

you could still write by hand on a recognition device/tablet and store it with strong encryption.

just glue a feather to your stylus and drip wax around the edges of your tablet for maximum effect.

TSK September 4, 2008 6:15 PM

But cracking those diary/document codes is important. So if cracking is so easy, why don’t cryptanalysists sacrifice one morning to decrypt a dozen documents to do science and humanities a favor ?

If I have a problem with math which I can’t solve, I am going to a mathematician. If I have a technical problem, I will go to an engineer. So why people don’t go to cryptanalysists if they have problems with encoded data, especially if it is so easy ?

Clive Robinson September 5, 2008 11:14 PM

@ Bruce,

Speaking of cryptographers not breaking codes etc. reminded me about your blog…

Do you ever read your 100 Comments page at the weekend or other low traffic times?

Well insomnia being what it is I do (no I’m not saying your blog is capable of inducing a new form of somnambulism in me, but I do 😉 need something to fill the dead hours of unwanted wakefullness so I do.

I have noticed a number of posts to “old pages” that are either extreamly short or so highly styalised they appear to have been machine generated.

At first as they all have “name links” I thought they where just for the placment of “enhancment” style products. However I then noticed that some of the short messages where almost but not quite identical but from differently “named” contributors.

Well I then noticed that a lot of these “funny posts” where to other peoples blogs and I thought “Bruce is being used as a way to improve somebody elses page ranking”

A look at one or two of the linked to blogs likewise showed these odd postings.

Then I remembered the other short messages that get posted that appear to be very short snippits of “in code” and insomnia being what it is I started to think about why.

And being a person who makes odd but correct connections I had been asked by a colleague about how “botnet and other malware operators communicate without getting caught”

I found myself thinking “If I where a botnet or malware operator how would I make a covert channel with good deniability”…

Probably a coincidence but no doubt you can see the way my mind has run with this one it will have a certain ironic flavour to see “Renowned security expert’s blog controls botnet” as a headline…

P.S. I hope I have not induced insomnia in you.

Beowulf September 8, 2008 11:48 PM

In the 19th century, it was very common for people to keep diaries, and they were often kept in some variety of Pitman shorthand, the dominate system at the time. So if you were a historian of the period, you would have to learn Pitman to read original documents written in it. Not a formal code, but — like Shelton’s system used by Pepys — a functional one.

The most famous literary use of shorthand as a code in a diary is probably by Johnathan Harker’s in Dracula. Dracula is totally befuddled by the system. (The book is told as a series of journal entries and letters by all the principle characters — except Dracula himself. Only Dr. Seward uses one of those new-fangled dictation machines invented by that Edison fellow.)

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