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 — obtain matrix key
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 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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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
$$ \begin{bmatrix} a_1 & a_2 \\ a_3 & a_4 \end{bmatrix}\begin{...
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1answer
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Unbreakable Hill cipher
Why don't we use hill cipher of 100 × 100? or even bigger. That would be closely unbreakable.
The number of keys possible 2 × 2 hill cipher is 157248. for 100 × 100 number is beyond limits.
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How does hill cipher key exchange takes place?
I am giving a presentation in my college where hill cipher is a part of the presentation. I just wanted to know, how is the hill cipher key matrix is exchanged securely in order to decrypt the message?...
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Clarification on Hill Cipher crib dragging technique
--- this has been edited as I realised the question was silly. replaced with helpful information ---
I want to confirm the following:
Given ciphertext "AGHTDIX... [cont.]" (C)
and crib (a word ...
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cofactor matrix in Hill cipher
I have been reading these slides about Hill cipher.
And there it says that the value of K is the following:
\begin{equation}
K=
\begin{pmatrix}
11&8\\3&7
\end{pmatrix}
\end{equation}
Now I ...
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1answer
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Hill's Cipher - Known Plaintext Attack
I know this question has already been asked few times but I'm struggling a bit on a problem.
I have a plaintext FRIDAY and its ciphertext PQCFKU, using $M = 2$, with corresponding integers $x = fr ...
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Hill-Chiffre - How can I find the Matrix $X$
This is a problem of classical cryptography: Hill-Chiffre
Where the matrix $A$ is the clear message and the matrix $C$ the coded message.
How can I find the Matrix $X$?
Which method I can use?
$$\...
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1answer
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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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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, $...
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what is number of invertible matrix m*m on$ 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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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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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 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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1answer
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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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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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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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1answer
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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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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, 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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2answers
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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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3answers
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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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1answer
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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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1answer
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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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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 ...
