[HAETAE update!] HAETAE version update v2.0

[Hyeongmin Choe]

Dear all, 

As announced during the 7th KpqC workshop, the HAETAE version update (v2.0) is now available!

We mainly focused on correcting the bugs in our reference implementation, e.g., issues raised in the pqc-forum, KpqC-related workshops, and other bugs we identified. 

We drastically reduced the size of the precomputation tables for the rANS encoding by minimizing the symbol space by rejecting *very* rare symbols. Some modifications led to changes in the distributions of the size of the compressed values, we therefore adapted the signature sizes slightly.

The updated reference implementation, an AVX2 optimized version, and an up-to-date specification with more detailed explanations of several implementation aspects can be found at: https://kpqc.cryptolab.co.kr/haetae. 

A version for embedded devices featuring the Cortex-M4 will soon be available via the pqm4 framework.

Best,

The HAETAE Team