Document domain points determinism in DKG instances

[piotr-roslaniec]

Type of PR:

• Other

Required reviews:

• 1

What this does:

• Documents deterministic behavior of domain points.
  • Determinism is based on the generator derived from rounding selected domain size. As long as the domain size remains the same, so does the generator. Hence, for certain sizes of the domain, the domain points generated are deterministic
  • The domain size is based on the validators_num parameter of the DKG. validators_num is rounded up to the nearest power of two. So as long as our validators_num is rounded to the same domain size size as validators_num of a different DKG instance, our domain points are the same.
  • See tests for examples of that behavior

Issues fixed/closed:

• Fixes #...

Why it's needed:

Explain how this PR fits in the greater context of the NuCypher Network.
E.g., if this PR address a nucypher/productdev issue, let reviewers know!

Notes for reviewers:

• Only the last commit is relevant to this PR
• Based on Key share refreshing ceremony refactor #175 - Please review it first

[codecov-commenter]

Codecov Report

Attention: 121 lines in your changes are missing coverage. Please review.

Comparison is base (72b8484) 78.28% compared to head (2161c1c) 79.96%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
ferveo/src/bindings_python.rs	63.15%	49 Missing ⚠️
ferveo/src/api.rs	92.81%	47 Missing ⚠️
ferveo-tdec/src/decryption.rs	26.31%	14 Missing ⚠️
ferveo/src/bindings_wasm.rs	0.00%	5 Missing ⚠️
ferveo/src/refresh.rs	98.67%	3 Missing ⚠️
ferveo/src/dkg.rs	98.62%	2 Missing ⚠️
ferveo-common/src/keypair.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #182      +/-   ##
==========================================
+ Coverage   78.28%   79.96%   +1.67%     
==========================================
  Files          24       24              
  Lines        5066     5914     +848     
==========================================
+ Hits         3966     4729     +763     
- Misses       1100     1185      +85     

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[cygnusv]

This test demonstrates that we'll have to deal with an existing restriction on domain set selection that implies that node replacement has to be implemented using domain point reuse, or in other words, not by assigning new domain points. See the plan laid out in #160 (comment)