sgmenda / cpp-scrypt Goto Github PK

Block mixing can be parallelized, implement it.

Balloon hashing looks really cool---implement it.

It would be nice to make this repo kinda self-contained. To do this, we need to implement PBKDF2_HMAC_SHA256. At minimum, this requires us to implement the following.

1. PBKDF2 (RFC 8018)
2. HMAC (RFC 2104)
3. SHA256 (RFC 4634)

I am lying a little here, we don't really need to implement HMAC in all its generality, we just need to implement SHA-HMAC (RFC 2104), but that doesn't seem much easier.

When I first started writing this, I had different goals in mind than I do now. Hence I think it's best to use a more appropriate license.

ChaCha20 (RFC 8439) is a refinement of Salsa20 (which is currently implemented in this repo). In the scrypt paper Percival mentioned (see footnote 15) that they chose Salsa20 over ChaCha20 because ChaCha20 was new at the time and hence less studied. Today, ChaCha20 has been studied and widely implemented. So, it makes sense to replace the Salsa20 in scrypt with ChaCha20.