Questions tagged [hill-cipher]
The Hill cipher is a historic polygraphic substitution cipher invented by Lester S. Hill in 1929.
39
questions
0
votes
0answers
32 views
Hill cipher. Any way around the not invertible matrices [duplicate]
Question: The plaintext JULY is encrypted using Hill Cipher with m = 2, to give the ciphertext DELW, then determine the encryption and decryption matrix
My approach: We will form a 2x2 matrix of ...
0
votes
0answers
38 views
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 ...
4
votes
2answers
98 views
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 ...
1
vote
1answer
92 views
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 ...
1
vote
1answer
144 views
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 ...
0
votes
1answer
124 views
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:
...
1
vote
2answers
157 views
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.
2
votes
1answer
194 views
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 ...
0
votes
2answers
264 views
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 ...
0
votes
1answer
118 views
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 ...
2
votes
0answers
319 views
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:
...
-1
votes
1answer
248 views
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
$$ \begin{bmatrix} a_1 & a_2 \\ a_3 & a_4 \end{bmatrix}\begin{...
2
votes
1answer
250 views
Unbreakable Hill cipher
Why don't we use hill cipher of 100 × 100? or even bigger. That would be closely unbreakable.
The number of keys possible 2 × 2 hill cipher is 157248. for 100 × 100 number is beyond limits.
1
vote
1answer
71 views
How does hill cipher key exchange takes place?
I am giving a presentation in my college where hill cipher is a part of the presentation. I just wanted to know, how is the hill cipher key matrix is exchanged securely in order to decrypt the message?...
1
vote
1answer
508 views
Clarification on Hill Cipher crib dragging technique
--- this has been edited as I realised the question was silly. replaced with helpful information ---
I want to confirm the following:
Given ciphertext "AGHTDIX... [cont.]" (C)
and crib (a word ...
0
votes
2answers
84 views
cofactor matrix in Hill cipher
I have been reading these slides about Hill cipher.
And there it says that the value of K is the following:
\begin{equation}
K=
\begin{pmatrix}
11&8\\3&7
\end{pmatrix}
\end{equation}
Now I ...
4
votes
1answer
5k views
Hill's Cipher - Known Plaintext Attack
I know this question has already been asked few times but I'm struggling a bit on a problem.
I have a plaintext FRIDAY and its ciphertext PQCFKU, using $M = 2$, with corresponding integers $x = fr ...
-1
votes
2answers
141 views
Hill-Chiffre - How can I find the Matrix $X$
This is a problem of classical cryptography: Hill-Chiffre
Where the matrix $A$ is the clear message and the matrix $C$ the coded message.
How can I find the Matrix $X$?
Which method I can use?
$$\...
2
votes
1answer
448 views
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?
1
vote
0answers
128 views
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, $...
0
votes
1answer
304 views
what is number of invertible matrix m*m on$ 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 ...
1
vote
1answer
545 views
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?
1
vote
1answer
1k views
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 ...
1
vote
0answers
3k views
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,......
2
votes
1answer
513 views
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 ...
2
votes
1answer
860 views
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 ...
1
vote
0answers
733 views
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: ...
1
vote
0answers
3k views
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 $p$, ...
2
votes
1answer
7k views
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.
2
votes
1answer
1k views
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 $...
1
vote
2answers
434 views
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 ...
1
vote
1answer
529 views
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 ...
1
vote
2answers
652 views
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 ...
4
votes
1answer
1k views
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 ...
5
votes
2answers
2k views
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 ...
4
votes
3answers
8k views
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 -...
4
votes
2answers
3k views
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-...
2
votes
1answer
5k views
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 ...
2
votes
1answer
605 views
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 ...
