No way to encode a digest directly?

[leavehouse]

Problem

If you have a hash digest digest: &[u8] and you want to encode that into multihash bytes, you're out of luck if you're using rust-multihash currently. This is because encode expects un-hashed data as input. Instead, you must do something like this manually:

    let hash_alg = multihash::Hash::SHA1; 
    let mut mh = Vec::with_capacity(digest.len() + 2); 
    mh.push(hash_alg.code()); 
    mh.push(hash_alg.size()); 
    mh.extend_from_slice(digest); 

In contrast, go-multihash's Encode function does not hash your data for you, so you can directly pass in a digest.

Potential solutions

This could be remedied with a new encoding function that expects a hash digest, maybe something named encode_digest? However, perhaps we should consider changing the way encode works. It would be a breaking change, but it would bring it in-line with how go-multihash works.

[vmx]

There is now a function called multihash::wrap() where you can encode a multihash from an existing digest.