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LeastAuthority / bls-hd-key

Apache License 2.0
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Salt reuse for every Hkdf generated #2

Open lilyannehall opened 4 years ago

lilyannehall commented 4 years ago

https://github.com/LeastAuthority/bls-hd-key/blob/master/src/key-derivation.ts#L9

Salt is hard-coded to the string BLS-SIG-KEYGEN-SALT-. Shouldn't we generate a new unique salt for every Hkdf and return it along with the result?

lilyannehall commented 4 years ago

Using a static salt makes generating a new rainbow table possible and largely defeats the purpose of using a salt at all. While this cases is different than salting passwords - assuming that the entropy source for keygen is not compromised there shouldn't be any key reuse between users (see https://github.com/LeastAuthority/bls-keygen/issues/1), I think we still want to recommend using unique salts.

lilyannehall commented 4 years ago

Backpedaling on this one given a secret key is involved and the implementation matches the RFC,