This repository contains the source code of reference implementations for various versions of Poseidon [1]. The source code is available in Sage. Moreover, scripts to calculate the round numbers, the round constants, and the MDS matrices are also included.
We fixed several bugs in the implementation. First, the linear layer was computed as state = state * M instead of state = M * state, and secondly the final matrix multiplication was missing. The test vectors were also changed accordingly.
[1] Poseidon: A New Hash Function for Zero-Knowledge Proof Systems. Cryptology ePrint Archive, Report 2019/458. https://eprint.iacr.org/2019/458. Accepted at USENIX'21.