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Questions tagged [arx]

Design philosophy for ciphers. ARX solely relies on additions, rotations and XORs to build ciphers and similar algorithms. This usually constructs ciphers that are highly resistant against side-channel attacks. Well-known examples are Threefish and Salsa20/ChaCha.

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74 views

Countermeasures to prevent integral cryptanalysis against 4-rounds AES

Integral cryptanalysis against 4-rounds AES is practical (Security of the AES with a Secret S-box). I did two experiments in order to find the impact and remove the integral distinguisher of 4 rounds:...
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Differential probability of modular subtraction $xdp^-$

The modular addition has been a main component in block cipher. The use of modular subtraction in block cipher is not common but there are some cipher such as Bel-T cipher which uses both modular ...
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1answer
229 views

Selection of rotation constants in ARX design

My question is about choosing the rotation values in ARX design such as SIMON-like or SPECK-like ciphers to provide optimal differential and linear immunity. According to this, the selection of $a$ ...
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2answers
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Achieving non-linearity in a block cipher using only, rotations, shifts, AND, OR, and XOR

It is supposedly difficult to introduce enough non-linearity in block ciphers based on modular addition, data-independent bitwise rotations, and XOR to make them secure against certain kinds of ...
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3answers
585 views

Weaknesses in ARX block ciphers

What are the weaknesses in a block cipher that uses modular addition, rotations with fixed amounts, and XOR? Can substitution boxes or permutation boxes be replicated with these three operations? ...
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1answer
114 views

Would modifying the key of an arbitrary ARX cipher make it harder to break?

Consider a simple ARX block cipher in which after each block is encrypted, the key is rotated and/or XORed by some variable value. Would this make the key any more secure, or just be a waste of time? ...
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How well do ARX algorithms preform (in terms of diffusion)?

I have been researching ARX algorithms, but I would like to know how well does ARX (both single or multiple rounds of) provide diffusion compared to an s-box or an SP network. Also, are there any ...
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1answer
283 views

Role of xor in ARX construction

In ARX construction like Salsa 20, why xor operation is required? That is why AR is not sufficient? Note that xor is a linear operation.
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Algebraic Attacks against ARX

I have not seen much about algebraic attacks against ARX ciphers. How would ARX ciphers compare in algebraic security to AES or Present or Simon?
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1answer
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How are boolean functions used in cryptography?

I recently started becoming interested in Boolean functions. Because they are defined as $f: \{0, 1\}^n \rightarrow \{0, 1\}$, or in other words only over $\{0, 1\}$, I guessed they can somehow be ...
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1answer
137 views

ChaCha20 core vs ideal unkeyed PRP

I know that the ChaCha20 core (without the initial constant) is not an ideal PRP and must not be used as such. I also know that $\text{ChaChaCore}(0) = 0$. Are there any other differences?
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1answer
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Which precautions to protect against side-channel attacks on ARX ciphers?

In recent crypto there has been a trend to design ciphers using only the ARX set of instructions - i.e. additions (modulo $2^{32}$ or $2^{64}$), rotations (by a fixed constant) and XORs, examples ...
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1answer
300 views

rotational cryptanalysis on modulo multiplication?

I saw the paper 'Rotational Cryptanalysis of ARX', it is effective against design primitives using XOR, addition, and rotation. http://www.iacr.org/archive/fse2010/61470339/61470339.pdf However ...
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1answer
404 views

Do data-dependent rotations have any advantage over fixed rotations?

There are many ARX ciphers, however most use fixed rotations. I know data-dependent compared to fixed rotations are: patented harder to implement constant time more expensive in hardware harder to ...