Questions tagged [classical-cipher]

Ciphers invented before the era of computers and modern cryptographic theory. Classical ciphers typically operate on letters instead of bits and are usually designed to be implemented by hand or using simple mechanical devices.

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Shannon's Diffusion: classical ciphers vs modern ciphers

Is there an easy to understand and intuitive "one fits all" definition for the concept of diffusion that is applicable to both modern binary cryptosystems as well as classical ciphers? For a ...
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How to cryptanalyze Bifid cipher?

this is my first question. I've been into classical cryptography for about a year or so, but I am getting started with cryptanalysis of these ciphers. I am trying to figure out how to reconstruct the ...
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For fun puzzle has me stumped on a book cipher [closed]

So originally a puzzle was given out to a community i'm a part of and what was given was this. . .. . ... . . . . . . . ... . .. . . . . . .. . ... . . . . . .... . .. . . . . . .. .. .. . . . . . .. ....
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Interesting and fun facts about cryptology [closed]

We are planning to organize a workshop with the participation of academicians, engineers and graduate students working in the field of cryptology. On the first day, we are planning a fun competition ...
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Could this be a cipher or not? [closed]

I am trying to solve a puzzle, and I think have to solve a cipher. But I'm not actually sure what I have to do ... Example : ...
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How to Calculate Digraphic/Trigraphic Index of Coincidence?

How do you calculate the digraphic and trigraphic IOCs and the same expected IOCs? I'm aware of the formula for calculating the single letter IOC which is given at this formula but I can't find the ...
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How do the notch and window positions on an Enigma machine correlate?

I am having difficulty visualizing the stepping process. The permutation of Wheel I of Enigma I is as follows: ...
354 views

Keyless cipher proof

I answered a question on StackOverflow yesterday that was asking why the following keyless encoding/decoding scheme for 16-bit numbers worked: Encoding Note that the "shift" operation is ...
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Is there any known/standard encoding or cipher method that uses a 64-character alphabet from byte 30 (ASCII 0) to byte 6F (ASCII o)?

Is there any known/standard encoding or cipher method that uses a 64-character alphabet from byte 30 (ASCII 0) to byte 6F (ASCII ...
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How do different types of ciphers relate to each other?

I understand that there are symmetric and asymmetric (public-key) cyphers. The first have the same key used for encryption and decryption, while the second use a public key for encryption and a ...
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Mathematical definition of scytale

Most cryptographers know the scytale. It is that cipher where you roll a leather strip around a rod and then write text on it. For encryption you roll it off the stick and for decryption you roll it ...
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Shift cypher, perfectly secure?

I know that if only one character is encrypted using a shift cipher, then the shift cipher is perfectly secure. But what if the space of keys is greater than the space of messages? Would it still be ...
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Analysis of the Vigenere cipher

Im just starting out learning some cryptoanalysis techniques. I came across an idea which analyzes the vigenere cipher. Essentially the video explains that there is a standard english probability ...
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Using ML to detect what classical cipher the ciphertext is encrypted with

I was considering creating an ML project where it is fed some ciphertext by any classical cipher and would return possible ciphers that encrypted the text. I would have to create a sizeable dataset ...
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Does machine cryptography only consist of rotor machines?

For the chronological categorisation of cryptography, I have proceeded as follows: Cryptography by hand (e.g. Caesar, Vigenére, etc., till around 1900/1920) Cryptography using machines (e.g. Enigma, ...
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How to encrypt affine cipher in block?

Assuming the alphabet of capital letters, if an affine linear cipher $v\to Av+b \bmod 26$ with block length $3$ maps plaintext ENCRYPTAGAIN to ciphertext ...
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How are the cipher, the key and the initial message (that is not encrypted) are releted?

Suppose that $m$ is a message that someone player $i$ wants to send to a network of other players $j\neq -i$. The player to prevent his message from cheating by others uses an encyrpstion scheme. Say \$...
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Classic cipher method [closed]

I am struggling with these two cipher texts, I cannot identify which king of cipher was used. First: otnpeetrnneepeufofutisrtrllohcdmetoeheeatyngonrmrm And second: ...