crypto: fix base58 encoding for BlsSignature

[emturner]

The current base58 module incorrectly had a 128 char limit set on decoding hashes - too small for bls sigs. We raise this limit to the length of BlsSigs hashes, which are the longest hashes we support.

fixes #49

[lierdakil]

The current base58 dep has a 128 byte limit

This is true, but 128 bytes is not the same as 128 base58 characters.

which is not long enough for bls sigs

This is false, base58 will happily accept about 175-176 base58 characters, which corresponds to around 128 bytes. Bls signatures are mere 96 bytes, which corresponds to 142 characters (with prefix) in base58.

So this was never a problem with dependencies. I thought I explained it in the issue.

[emturner]

The current base58 dep has a 128 byte limit

This is true, but 128 bytes is not the same as 128 base58 characters.

which is not long enough for bls sigs

This is false, base58 will happily accept about 175-176 base58 characters, which corresponds to around 128 bytes. Bls signatures are mere 96 bytes, which corresponds to 142 characters (with prefix) in base58.

So this was never a problem with dependencies. I thought I explained it in the issue.

Ah thanks, apologies for the misunderstanding. Have updated

[lierdakil]

Hmm. I did some testing, and apparently I was under a few misconceptions. Apologies.

So while this works fine for bona fide Tezos hashes, there's an unfortunate landmine in the base58 library related to handling zero data: it will panic if there are more than 128 leading characters 1 in the input (which translate to zero bytes). So that explains why the check in from_base58check was so strict.

Hence, it turns out, the library switch was a better overall fix.

Can you revert back to f625864? Again, sorry for this.

[lierdakil]

LGTM with a couple suggestions.