# Questions tagged [hill-cipher]

The Hill cipher is a historic polygraphic substitution cipher invented by Lester S. Hill in 1929.

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### Hill cipher, unknown letter value

I've been struggling on this problem for a while now : the Hill cipher is well-known to be vulnerable to known-plaintext attack due to its linearity. Given a key matrix $K$ of size $n\times n$, one ...
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### Hill Cipher known plaintext attack

I know a plaintext - ciphertext couple of length 6 for a hill cipher where its key is a [3x3] matrix. Based on what I've read and learned, to attack and crack keys of [n x n], if we know a plaintext -...
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### Are there ready-to-use software that can try many decryption techniques on a ciphertext, with no information?

Let's say I receive a 1 MB encrypted file, but I get no information about the encryption method, and no password. The only thing I can guess is that the person probably used a weak encryption method ...
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### Hill Cipher question

Recently, I was given three ciphers to crack for my cryptography class. At this point, I have guessed that one of them is likely a Hill cipher (probably 3x3, as that is the most complex we have done ...
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### Hill cipher cryptanalysis - known plaintext known key size

Hello I want to know how to go about this problem I know the plaintext "abcdef" and the ciphertext. The key size is 2. I really can't figure out how to find the key for decrypting and encrypting.
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### Security analysis of a "one-time pad" type hill cipher

Suppose the Hill cipher were modified to something like a one-time pad cipher, where Alice wants to send a message to Bob, and she chooses a key matrix randomly everytime a new message is sent (and ...
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### Block cipher linearity (in relation to hill ciphers)

So while I knew hill ciphers were a form of block cipher (I'm assuming all the ones I have solved to date were ECB or something similar), so that got me thinking. Is it possible to use hill ciphers in ...
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### Hill cipher: How to find an unknown key of unknown size

How would you tackle the problem of finding the key (you don't know the length) to a Hill cipher when knowing only one 12-letter word of plaintext and its corresponding ciphertext? CONVERSATION has ...
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### Security of the iterated Hill Cipher

I can understand that the basic Hill Cipher is susceptible to known plaintext attacks, but suppose the Hill Cipher is modified into the Iterated Hill Cipher. For a plaintext $x_0=m_0$ and an ...
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### What are some statisitcal characteristics of a hill cipher?

Given a ciphertext, after performing a frequency analysis on it, how would you identify it as a hill cipher? What should i expect to see in the statistics?
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### How can I determine the Hill cipher key in this case?

I have been struggling with a Hill cipher problem for many days, without any luck. I have the following ciphertext, which I know is an encrypted excerpt from an Edgar Allan Poe story: ...
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### Z superscript confusion

I was practicing some questions on cryptography (newbie) and came across this question: I know that Z26 means modulo-n arithmetic is used, but what does the superscript (3) denote? My guess is that ...
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### Hill Cipher with unequal matrix

How can we encrypt a text in Hill Cipher with a key matrix that is 3x3 when the plaintext is even like "ATTACKS"? Do we need to add padding like "x" or "z" to make the matrix equal? Thanks.
1 vote
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### How does hill cipher key exchange takes place?

I am giving a presentation in my college where hill cipher is a part of the presentation. I just wanted to know, how is the hill cipher key matrix is exchanged securely in order to decrypt the message?...
1 vote
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### How to encrypt letters less than block n using Hill Cipher

I am learning about Hill Cipher and know that it is a block cipher where each block of n letters (considered as an $n$-component vector) is multiplied by an invertible $n \times n$ matrix, again ...
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### Are there any hand ciphers not obsoleted by computer cryptanalysis? [duplicate]

Computerized cryptanalysis has obviously made formerly "secure" hand ciphers like Playfair, Four Square, and the Hill Cipher obsolete because they can be defeated in seconds. But is there a hand ...
1 vote
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### Hill cipher concepts

I have some questions about the Hill cipher. There is a rule for key K: Determinant of matrix and number of characters of the alphabet must be coprime. What does ...
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### Hill Cipher Plaintext Attack: Dealing with Non-uniqueness of Matrix Inverses?

I'm following along with my book. Here is an example of a plaintext attack from it: It is known that: plaintext = 'friday' ciphertext= 'pqcfku' $m$ = 2 We will use this to form the following matrix ...
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### Clarification on Hill Cipher crib dragging technique

--- this has been edited as I realised the question was silly. replaced with helpful information --- I want to confirm the following: Given ciphertext "AGHTDIX... [cont.]" (C) and crib (a word ...
1 vote
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### Hill Cipher the point of a known plaintext attack question

Is the point of a known plaintext attack on a Hill Cipher to get the matrix key?
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### hill cipher encryption way 1x3 plaintext matrix

Can someone help me with a Hill cipher? When do I have to use: 1x3 plain text matrix (p1, p2, p3) * 3x3 key matrix 3x3 key matrix * 3x1 plain text matrix Or they are both correct? I tried to ...
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### Hill Cipher - Unknown plaintext attack, known key [duplicate]

I was wondering if I have the key and the encrypted Hill Cipher message(s). I can definitely figure out the charset involved. But the order is missing. Assuming that I use 37 modulo or higher. How ...
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### How to uncover keys from using double encryption schemes such as Hill and Vernam Cipher

I have a quick question. How would you decrypt an encryption scheme, involving both Hill and Vernam Cipher. The order of encryption is Hill Cipher then Vernam Cipher. Problem is that only final cipher ...
1 vote
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### Calculate the key of a Hill-cipher using known plain- and ciphertext

I know I should calculate the multiple inverse of plaintext with ciphertext $\pmod {26}$. However, the problem I have is that the plaintext is a $3 \times 4$ matrix which is not square, so how would I ...
1 vote