# Eaglesong: an ARX Hash with Fast Diffusion

* Eaglesong is a hash function designed for CKB proof-of-work.
    
* It is designed with hardware-acceleration in mind, as we believe specialized mining hardware can boost the network's security.
    
* The detailed design is described in [this paper](https://acad.ro/sectii2002/proceedings/doc2020-1/09-Szepieniec.pdf).
    

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## **Abstract**

This paper proposes a hash function based on three design principles: the sponge construction, ARX operations, and the wide trail strategy. While the sponge construction applies generically to any sufficiently strong permutation, the wide trail strategy and the ARX operations are naturally somewhat incompatible. We show that while the ARX operations provide only very weakly nonlinear S-boxes, it is possible to build very strong linear diffusion layers with them. As a result, the wide trail argument, which bounds the attacker’s success probability in terms of the minimum number of active S-boxes across two rounds, survives. The proposed hash function is one of a very select group of ARX ciphers featuring rigorous bounds against differential and linear cryptanalysis.

## **Authors**

[Alan Szepieniec](https://twitter.com/aszepieniec) , [Tomer Ashur](https://twitter.com/tomerashur)

## **Published in**

Romanian Cryptology Days / Proceedings of the Romanian Academy, Series A, Volume 21, September 2019

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*By the same author:*

* [Polynomial IOPs for Linear Algebra Relations](https://blog.cryptape.com/polynomial-iops-for-linear-algebra-relations)
    

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