The Book Cipher Explained - Encryption & Decryption Using a Book
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- Опубліковано 30 вер 2024
- #cryptology, #cryptography, #cryptanalysis
In this video, we explain how a book cipher works. First, we have a short look at the background of the book cipher and three famous examples, where book ciphers were used in history. Then, we explain how the cipher works. Finally, we encrypt and decrypt using the book cipher component of CrypTool 2.
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Book ciphers are the best to use in spy stories as the heroes have something to chase after and the audience can easily understand. Nils, have you heard of the telegraph code books used for cheating telegraph rates? Find "The Universal Telegraph Code Book" and the Chinese "CCC" book.
Yes, I have heard :-)
Hallo Nils,
I have been reading the memoirs of Leo Marks and Hermann Giskes.
I think a video about the "Poem Codes" used by S.O.E. agents would interest other viewers. The topic is of historic interest and is also quite a romantic notion in a normally very dry procedure.
"While I nodded nearly napping, suddenly there came a tapping...
di-DA-DA-dit DA-DA-DA dit"
Thx for the tip,
will put it on my list. Right now, I have so many different things to do, so it will take some time until I have time to look :-)
Greetings,
Nils
Thanks for a great detailed explanation!
You are welcome :-)
Njstar has a Chinese ccc lookup tool and Archive has cassell's 1889 telegraph phrasebook
Question for you…do you know if Cryptool 2 can run on a Mac using an emulation layer?
Hiho,
It only runs in Windows. The only possible solution for Mac right now is to install a virtual machine with Windows :-/
Greetings,
Nils
What is the strength of a book cipher ?
Hiho,
Very difficult, but hard to put into a number. It depends on your method of encryption, how likely it is to find the correct book, etc. But in general it is very hard to solve even "unsolvable" without a copy of the used book.
Greetings,
Nils
difficult to quantify but you usually talk about security of encryption schemes. Is there any consensus?
Good question: I know that the German BSI predecessor "Zentralstelle für das Chiffrierwesen" (ZfCh) deciphered book ciphers of East German spies, because the spies used poems and books that the ZfCh found/knew. So the problem in this case was the (more or less easy) availability of the keys used.
In contrast, look at the Beale ciphers, where we only know the solution to one of the three messages...
So I would argue that the security is based on the secrecy (and/or availability) of the "books" (the keys) used for encryption. If used carefully, the book ciphers can come close to the security of a one-time pad, I would argue.
I Hope you do the same with the book of OTP from russian guys.
Can you pinpoint me to what you exactly mean :-) ?
Ah, what if you used a book as a OTP pad?
Yeah, each letter would represent a number.
Then just follow the OTP procedure.
Then have your agents subscribe to a “book club”. So mailing them their pads wouldn’t be so incriminating.