holepunchto / hypercore-crypto Goto Github PK

Hey,

Today we update hypercore-crypto and it seems that b4a is missing some buffer operations for the browser, one of them is writeUInt32BE and it breaks the encodeUInt64 of hypercore-crypto.

index.js?fc28:14 Uncaught (in promise) TypeError: buf.writeUInt32BE is not a function
    at Object.exports.encode (index.js?fc28:14)
    at encodeUInt64 (index.js?4681:184)
    at Object.exports.data (index.js?4681:104)
    at MerkleGenerator.exports.leaf [as _leaf] (index.js?4681:112)
    at MerkleGenerator.next (generator.js?b45a:37)
    at Feed._append (index.js?d11e:1500)
    at work (index.js?d11e:158)
    at Feed.append [as _batch] (index.js?3518:44)
    at Feed.append (index.js?d11e:1404)
    at eval (index.js?44d0:106)

sodium.crypto_generichash expects an input buffer of arbitrary length and an optional key. According to sodium docs the input is hashed, and the optional key "can be used to make sure that different applications generate different fingerprints even if they process the same data." and different keys "are very likely to produce distinct fingerprints". This "very likely" seems to suggest that this is not as reliable as a hash.

The sodium-native docs say the input is the second arg, and key is the third arg, however discoveryKey seems to call the arguments in the wrong order:

exports.discoveryKey = function (tree) {
  var digest = bufferAlloc(32)
  sodium.crypto_generichash(digest, HYPERCORE, tree)
  return digest
}

As far as I understand, HYPERCORE should be the key. I understand from #3 that tree is actually the publicKey. The consequence of this (I think, although I don't know the internals of sodium) is that the hash is not as guaranteed against collisions. It may be that this doesn't matter and changing the key is being hashed with the same algorithm as the input, but it doesn't seem like this was the intended way for this to work.

• https://github.com/mafintosh/hypercore-crypto#hash--cryptodiscoverykeypublickey
• https://github.com/mafintosh/hypercore-crypto/blob/09b09cfc80f6e0aa51e1dee1bab6e948ca5c6a60/index.js#L84

For example, leaf and parent.