Integration of mimc hashing for root calculation

MirandaWood commented 4 years ago

This PR enables timber to look out for a hash switch (HASH_TYPE) defined in nightfall (or another application) and calculates sibling paths accordingly. Shouldn't be any breaking changes since if HASH_TYPE is not defined, Timber will revert to using SHA as normal. Can be tested by changing the HASH_TYPE in docker-compose.pull for deployer.

Key changes:

ConcatenateThenHash now uses mimc hashing iff HASH_TYPE is set to mimc
Config changes length of zero hex depending on the HASH_TYPE (sha uses 27 bytes, mimc 32)
Small changes to avoid bugs when the frontier is empty

iAmMichaelConnor commented 4 years ago

Many thanks for this @MirandaWood

(To any other reviewers): I'll definitely need to review this before it is merged.

iAmMichaelConnor commented 4 years ago

@MirandaWood I've done a few small bug fixes:

rebased relative to a recent commit to master
added a missing dependency to package.json
fixed the deployer test
made the mimc.sol compile with solidity v0.5.8

I've tested, and all your changes work perfectly.

MirandaWood commented 4 years ago

@MirandaWood I've done a few small bug fixes:

Fab, thanks so much!

github-actions[bot] commented 4 years ago

:tada: This PR is included in version 2.1.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket:

EYBlockchain / timber

Integration of mimc hashing for root calculation #6