Questions tagged [affine-cipher]
A type of monoalphabetic substitution cipher, wherein each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple function `(ax + b) mod m`.
47 questions
1 vote
0 answers
64 views
Affine Transformation for "Securly" Comparing Integers
I just got into homomorphic encryption and multiparty computation. I thought about the following protocol for number comparison. We use a treshold homomorphic encryption scheme (like the treshold ...
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2 votes
1 answer
95 views
Conceal time-based GUIDs with an affine-cipher?
I'd like to create a custom type of sortable GUID by concatenating an 8-byte nanosecond timestamp, 6 random bytes, a 1-byte node number, and a 1-byte counter. But, such a precise timestamp can be used ...
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1 vote
1 answer
1k views
Where did affine cipher get its name from?
I was wondering where did affine cipher get its name from. I am curious to know its origin and how it is related to the cipher. The Affine Transformation page on Wikipedia states: In Euclidean ...
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0 votes
0 answers
121 views
How to encrypt affine cipher in block?
Assuming the alphabet of capital letters, if an affine linear cipher $v\to Av+b \bmod 26$ with block length $3$ maps plaintext ENCRYPTAGAIN to ciphertext ...
1 vote
2 answers
286 views
Can all affine cyphers be expressed with this formula
There are $26!$ permutations of the English alphabet. In Modern Cryptography textbook, William Easttom states that the basic formula for any affine cipher is $ax + b \equiv \pmod{26}$. I'm wondering ...
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0 votes
1 answer
247 views
Affine Cipher: what to do if the number isnt invertible over mod n? [duplicate]
I am currently solving a simple cryptanalysis problem where I need to decrypt a text file using frequency analysis. The text has been encrypted using an affine cipher over a 68 character alphabet ...
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0 votes
0 answers
94 views
decode Vigenere cipher that was encoded with Affine cipher
How do I decode some text that has been encoded like this: affine(vigenere(text, vigenere_key), *affine_key)? I don't know keys to either of them. At first I ...
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3 votes
2 answers
2k views
Text cipher option that can decrypt the same ciphertext to two DIFFERENT and DESIRED outputs given DIFFERENT keys (and/or alphabet)
I have a pen pal that I discuss with. In our latest discussion it was proposed to write a short message that is ciphered and have the other one find what it is, given some clues. I would like to ask ...
0 votes
3 answers
675 views
Linear subspace and Affine subspace
I am currently reading a paper titled "Another view of division property" and encountered the terms "Affine subspace" and "Linear subspace". I am new to the field and having some difficulties to ...
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0 votes
0 answers
78 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 ...
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0 votes
0 answers
35 views
How would you decrypt an affine cipher with only the ciphertext? [duplicate]
If I have only the ciphertext but the alphabet and the value of a and b are all unknown ... how would I go about this? I understand decryption with the key and alphabet, that is fairly easy but if we ...
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1 vote
0 answers
54 views
Proving at most one affine permutation mapping $x$ to $u$ and $y$ to $v$ with $x,y \in \mathbb{Z}_n$ and $\gcd(x−y,n) = 1$
Suppose that $x,y \in \mathbb{Z}_n$ with $\gcd(x−y,n) = 1$. Prove that for any $u,v \in \mathbb{Z}_n$ there is at most one affine permutation mapping $x$ to $u$ and $y$ to $v$.
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0 votes
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54 views
What choices of $a$ and $b$ of the affine cipher lead to proper encryption functions [duplicate]
Suppose I consider the affine cipher defined by $E(x) = ax + b \bmod n$ on the standard alphabet of 26 letters. Which choices of $a$ and $b$ lead to proper encryption functions? Using the ...
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-1 votes
1 answer
147 views
use of encryption of plain text from 1 instead of 0
while encrypting the plaintext in an affine cipher we encrypt the alphabets with a=0,b=1,c=2,......z=25 and then use the modulo of 26. Can we instead use to encrypt the plaintext with a=1,b=2,c=3,....,...
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2 votes
1 answer
1k views
AES with linear S-Box
If the AES S-Box is replaced with a linear or affine transformation, for instance the identity mapping $\sigma(x)=x$, does the cipher become entirely affine and hence trivially weak?
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