Questions tagged [hill-cipher]

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

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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 ...
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Help With Weird Hill Cipher On Phone After Network Intrusion [closed]

Hackers Left a Hill Cipher on My Phone. I found the cipher below after experiencing a network intrusion. Decode.fr identifies it as a hill cipher. It was typed out on my phone when I was not looking. ...
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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 ...
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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 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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An unbreakable Hill cipher?

Why don't we use a Hill cipher of 100 × 100? Or even bigger? That would be close to unbreakable. The number of possible keys in a 2 × 2 Hill cipher is 157248. For 100 × 100 the number is beyond limits....
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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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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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Impossible hill cipher question

I've been trying to solve this question from Forouzan's book ("Cryptography And Network Security") and haven't been able to wrap my head around how to solve it. The plaintext “letusmeetnow” ...
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Where can I find standardized implementations of lightweight cryptographic ciphers?

I am working on a project that requires encrypting messages with different ciphers. I am looking for the following ciphers: PRESENT, CLEFIA, LEA, Hill cipher, Affine cipher, Elliptic Curve ...
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Figuring out key in hill cipher (chosen-plaintext attack)

I have been wondering what approach to take in order to figure out what key was used to encrypt a message using the hill cipher. I know it is possible to obtain it even if it were just a known-...
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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 -- obtain matrix key [closed]

I have to solve Hill's cipher. I have only cipher text: CGQIYN and key: CFDG. I don't know how to decrypt it, because in all ...
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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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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.
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Problem while decrypting Hill cipher

I have a plaintext "monday" and ciphertext "IKTIWM" and $m=2$. I want to find the key of the Hill cipher. I made a matrix $$ \begin{bmatrix} a_1 & a_2 \\ a_3 & a_4 \end{bmatrix}\begin{...
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Hill Cipher how to encrypt and decrypt when both "I" and "J" are in plaintext

In Hill Cipher, let's assume the key is "KEYWORD" and I want to encrypt "JUICE", so after encryption, I get "GXLBWU", and when decrypt ciphertext I get back "IUICEX" not "JUICE". So my questions are: ...
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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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Hill Cipher if the length of the string is not divisible by the Key Dimensions

For a project, I want to encode the word "MEMBRANOPHONES" with the key "MULTITONE". I try spliting "MEMBRANOPHONES" into groups of 3, but then I get "MEM", "BRA", "NOP", "HON", leaving me with a 2 ...
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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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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?...
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cofactor matrix in Hill cipher

I have been reading these slides about Hill cipher. And there it says that the value of K is the following: \begin{equation} K= \begin{pmatrix} 11&8\\3&7 \end{pmatrix} \end{equation} Now I ...
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what is number of invertible matrix m*m on$ z_n$? [closed]

‎ ‎‎please help me what is number of invertible matrix $‎m*m$‎‎‎ on Group $\mathbb{z}_n$ ?‎‎‎, assuming we know‎ this number in $\mathbb{Z}_p \quad$ (‎p is prime‎‎) is $‎(p^{n}-1)(p^{n}-p) \cdots ...
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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 ...
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Can Hill Cipher be considered as Asymmetric?

I know hill cipher is a block chipher ,We produce decryption key by inverse of key matirx but we still use different key for decryption. Therefore Can we say that Hill cipher is asymmetric chipher?
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Hill's Cipher - Known Plaintext Attack

I know this question has already been asked few times but I'm struggling a bit on a problem. I have a plaintext FRIDAY and its ciphertext PQCFKU, using $M = 2$, with corresponding integers $x = fr ...
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Hill-Chiffre - How can I find the Matrix $X$

This is a problem of classical cryptography: Hill-Chiffre Where the matrix $A$ is the clear message and the matrix $C$ the coded message. How can I find the Matrix $X$? Which method I can use? $$\...
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Security of a custom non linear hill cipher

Initially let me state that this is an atypical type of cryptographic encoding. First I break up my key into three parts $k = {W,\overrightarrow{b},\alpha}$. the $W$ is simply a $n \times n$ matrix, $...
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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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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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how to find key matrix in hill cipher

I want to solve this problem but there are 3 known plaintext-ciphertext pairs. The key of Hill cipher is a 3*3 matrix as k=[k1,k2,3; k4,k5,k6; k7,k8,k9] where the unknown ki={0,1,...25}={A,B,......
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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 key space

Key space is the set of all possible keys that can be used to generate a key. We using the number of valid key to describe it. I've given a hill cipher of block size $k$ over alphabet of size $p$, ...
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Hill cipher is not perfectly secure

I am on cryptography course and there is a homework question to show that Hill cipher doesn't have perfect security. So assume we have an cryptosystem $(P,C,K)$, where $P = C = \mathbb Z_{26}^N$ and $...
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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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How can I decode a Hill Cipher without a key? [duplicate]

On my exam, we had to solve this problem: message matrix is: [20, 19, 14; 17, 0 10] and the ciphertext matrix is: ...
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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 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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Calculating the inverse modularity of the determinant for Hill cipher

I'm trying to decrypt a message encrypted with Hill Cipher, but I don't understand how to find the determinant so it solves the equation $det * 1/det = 1 mod 26$. The determinant for my key matrix is ...
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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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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 ...
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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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Hill-cipher, disordered alphabet

I am going to apply a simple substitution cipher to my input, then encrypt the result with a Hill cipher. How can this be broken, in a chosen-plaintext threat model? In other words, instead of the ...
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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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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 ...