cfrg/draft-irtf-cfrg-ristretto255

draft-irtf-cfrg-ristretto255's Issues

Mention the identity element and its encoding

The identity element just works with encoding and decoding, and there is a test vector for it in the appendix, but I feel like it might be worth calling out in two other places:

• in Section 4, spelling out its encoding and the fact that it does not require special handling
• in Section 7, to remind implementers that even if there are no invalid or low-order points, protocols might still have to check for equality with the zero element

Call out malleability and uniformity properties

Encodings are unique, not malleable, but not uniform. We should probably say that in Section 4. We might also warn against relying on them being uniform in Section 7.

Relatedly, it might be worth mentioning in Section 4.2.4 that there are multiple one-way map inputs that generate the same output. We might also want to remind implementers of the importance of uniform inputs to the one-way map in Section 7.