multicodec

I've used LEB128 (with canonicalisation) extensively and... this looks so much nicer for most use-cases (length prefixed, supports the full uint64 range without that extra 10th byte). The downside is the encoding size. LEB128 quickly grows to 2 bytes, but stays at 2 bytes all the way to 2^14. This is important if you're using these numbers as tags/identifiers as we were in the multicodec [1] project, or for network message lengths. bijou64 only gives you 500 <= 2 byte numbers. [1]: https://github.com/multiformats/multicodec

Codes reserved for app-specific things should satisfy your concerns. coming soon: https://github.com/multiformats/multicodec/issues/39 One thing you should consider about using full names (like "sha2-256") is that you still have to keep a table. What does "sha2-256" even mean? you know from context. you know that maps to a particular algorithm and particular set of implementations from context. Writing a table and distributing is cheaper than writing a new implementation of a new hash function and distributing. The "distributing code" part still has to happen. I think what you would like is if some body (NIST + all others who make hash functions) was maintaining the registry. That's fine, we can give this table onto IANA (though that's harder to update than a PR on Github).

Also see the multicodec table for codes of ethereum/bitcoin/zcash/stellar https://github.com/multiformats/multicodec/blob/2725f3c5cd7b...