Pr 2

[Al-Kindi-0]

Implementing Rescue prime, with optimizations, in the 64bit prime field in Montgomery form.

[bobbinth]

Looks great! Thank you! A few comments:

1. I think this is not based on the latest version of the codebase which is currently in Winterfell. You should probably update your fork to the latest version and then rebase this (and the other PR) from that.
2. Let's move mds_multiply_freq() and all associated functions/constants into a separate module - e.g., mds_freq.rs. I think this code deserves its own module.
3. Let's also have the fully defined MDS matrix exposed as a constant (this will be needed once you rebase from latest changes).
4. Let's add some tests to make sure naive MDS matrix multiplication (using fully defined MDS matrix) gives the same results as the one using mds_multiply_freq(). These tests could also go into mds_freq.rs file.

[Al-Kindi-0]

Thank you for the feedback!

1. I did that for both. Let me know if that works.
2. Done. Let me know if the documentation is enough and if some of the functions defined there should not be.
3. Did that instead of the old one. Where are these used exactly? I am still getting the "unused" warning.
4. Added a simple one so let me know if it should be changed.