# Questions tagged [xor]

XOR, often written ⊕, is one of the basic operations on bits and bit-sequences. It is a building block of many cryptographic primitives (and some higher-level algorithms, like modes of operations).

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### Best *deterministic* scheme (no SSSS) to turn a secret into 6 shards—with any 2 of these rebuilding the secret

What's the best deterministic scheme (i.e. no Shamir Secret Sharing Scheme) to turn a secret into 6 shards—with any 2 of these shards rebuilding the secret?
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1 vote
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### What is the XOR count of AES MixColumn matrix?

I am a beginner and I am learning about XOR counts, (Link to background: https://ia.cr/2014/530). The 4 by 4 matrix used in the MixColumn operation in AES is [2,3,1,1],[1,2,3,1],[1,1,2,3],[3,1,1,2]. I ...
190 views

### How to prove the conclusion " linear operation $\mathsf{XOR}$ does not affect the division property"?

Division property is proposed as a generalized integral property at Eurocrypt 2015 by Yosuke Todo in his paper Structural evaluation by generalized integral property, And in paper Integral ...
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145 views

### Finding good shift operators for XorShift

I'm not certain this is the right place to ask but I'll ask anyway. I've been messing around with XorShift random number generators, I've only implemented a simple one copied almost verbatim from the ...
38 views

### In the context of Hardware Security and Cryptography, how do I calculate the Algebraic Normal Form for sboxes [duplicate]

In our hardware security exercise, I am trying to calculate the ANF function manually (Sboxes) for the given table: And I came up with the result as: I thought I was calculating it correctly using ...
1 vote
54 views

### Differential uniformity of vectorial Boolean function

What could we say about differential uniformity of (a vectorial Boolean function) $F = f+g \pmod 2$ (i.e. XOR) in terms of differential uniformity of $f$ and $g$?
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### Can I recover the seed used to generate the internal state of MT19937 using the state itself?

Is there any way to extract the seed that has been used to generate the state in python or any other language? I tried to find the implementation of the random.seed ...
42 views

1 vote
60 views

### Identified Performance Discrepancy in my AES addRoundKey: Slower than Expected

Problem I'm working on an AES implementation in C++, and I have been testing the performance of my code, and its functions. I've noticed a significant performance slowdown in my 'addRoundKey' function....
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### Advantages of AES vs XOR on a plain text file

Currently, I am using AES-GCM to encode and decode a plain text file. The key is derived from a plain text password using PBKDF2 and a random salt with SHA-256. However, I have been thinking and came ...
37 views

### Solving XOR modular system of equations

I have the following problem. Here's a rephrased version of your problem, keeping the LaTeX commands unchanged: We are given $n \in \mathbb{N}$, $p, q \in \mathbb{N}$, and $y \in \mathbb{N}^{n+2}$. ...
• 111
1 vote
157 views

### Solving equation of xor and mod operation

How do I solve equations like this $$(aX \oplus X+b) \bmod M = c$$ If a,b and c are known? and if i have system of of equation with different b values, is it solvable? I am particularly interested in ...
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1 vote
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### Long Random Key and XOR - How Secure?

I have an application that encrypts files in the following manner (I think I can hear sighs already but bear with me): Start with two byte arrays generated from random strings of lengths l1 and l2 (...
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1 vote
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### Security of keys that are as long as the data

If both communicating sides end up with the same secret 3000-bit key, is it enough to XOR each byte of the messages with each byte of the secret key to make it secure? Wikipedia says it is, but I ...
157 views

• 573
1 vote
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### What is the security of XORing SHAKE256_XOF with itself?

After reading "Can the xor of two RNG outputs ever be less secure than one of them?" I wondered if you can increase security of SHAKE256_XOF by using ...
• 175
2k views

### How can I decode a XOR cipher with a string key I know?

I have a text that has been XORed with the key "77U" (I am sure of this as it is a file created by a code I have, so I have seen every entry getting XORed by 77U. However, none of the online ...
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54 views

### Is multiple encryption with XORs between each encryption operation susceptible to meet-in-the-middle attacks?

Let's suppose I take a cipher with key size equal to the block size (Threefish). I XOR a random block in the ciphertext, encrypt with a key, XOR another random block, encrypt again with another key ...
• 877
142 views

### Hamming distance between product and carry-less product

Motivation. There is a fast approximation to conventional multiplication. It conceptually works like long multiplication except for the fact that the carry is discarded instead of applied to the more ...
430 views

### Why is this code working

I was doing some introductory challenges at CryptoHack and one of the challenges, more precisely it was Favourite Byte, XOR with a single byte. I did my solution with XORing given string and single ...
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