Questions tagged [unicity-distance]

The unicity distance is the average amount of ciphertext a computationally unlimited attacker needs to obtain in order to uniquely determine the correct decryption.

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Unicity Distance redundancy clarification

I have an example of an exam question here: The open message source is a language with an alphabet represented by an 8-bit ASCII code stored in a byte (=8 bits). The relative redundancy of the ...
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How can I calculate the unicity distance as a function of the number of bits encrypted?

I know that the unicity distance of some encryption algorithm with a given key entropy $H_K$ encrypting a message with per-character redundancy of $D$ is $\frac{H_K}{D}$, and that the per-character ...
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What is the easiest encryption/cipher to brute force?

This is just a casual exploration of what could be effectively the worst possible block cipher, but I think it has some educational value on how ciphers work. I've been reading about unicity distance ...
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How to calculate the redundancy of a language

I originally asked this question on the information security stack exchange but I think it's better suited here. I'm trying to calculating the unicity distance for a cipher applied to a language I ...
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Exercise: recognizing Hawaiian plaintext

I was given the following exercise to solve: The Hawaiian language consists of 12 letters. There are 7 consonants: HKLMNP and W and there are five vowels: AEIO and U. In a word, no two consecutive ...
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Unicity-distance of Playfair

Given the classical scheme Playfair, say, for 5*5 matrices, I am interested to determine its unicity-distance. How should one proceed to properly do that? I should appreciate it, if I could obtain a ...
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Unicity Distance - AES

I am quite confused calculating the unicity distance and I was hoping that someone can clarify some things for me. My main issue comes from somewhat a difference of the calculation given by our ...
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How to accurately calculate Unicity Distance for English?

The Unicity Distance for the DES cipher is around $8.6$ characters, and can be calculated using the $U=H(k)/D$ formula, where $D = R - r$, and where $R = 8$ is the number of bits in a byte (ASCII is 7 ...
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Which characters to take into account when calculating unicity distance?

I need to calculate the unicity distance of a block cipher. Assuming I know that the plaintext is an English message I considered using 53 as the size of the alphabet, since the message could contain ...
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