Buffer error with keccak256 related to abi.encodePacked about ethereumjs-util

[alcuadrado]

This issue caught my attention, as I thought that maybe the new keccack version was broken. This is the first release with an N-API based dependency, so something may have been wrong.

The problem comes from using keccakFromString here: https://github.com/naszam/oz-merkle-support/blob/master/test/merkleTree.js

That function is intended to hash utf8 encoded strings. What you want to do is transform hex encoded data into buffers, and then hash that. keccak(toBuffer(data)) would do it.

I tried this change in your repo and it fixed it.

[holgerd77]

//cc @ryanio @cgewecke

[ryanio]

hey @naszam, thanks for sharing. could you let us know exactly what error you are encountering, and a minimal case to reproduce the issue?

[cgewecke]

@naszam Read the OZ thread and I see that the maintainer responding to your question says

I had to use the v6.2 release of ethereumjs-util rather than the v7 as I was getting errors that I didn’t explore

.. and then links to the release notes.

Do you have an example stack-trace for the error?

In v7, the methods are type-strict - it's possible you just need to input parameters with the correct data type for the method you're calling. For example, keccak256 now requires a buffer input by default. And there are convenience methods like keccakFromString that will hash a string.

[naszam]

This is a repo I've created to reproduce the issue:

https://github.com/naszam/oz-merkle-support

[cgewecke]

@naszam

• cloned https://github.com/naszam/oz-merkle-support
• npm i
• launched ganache-cli separately
• npx truffle test

Error: Could not find @openzeppelin/contracts/cryptography/MerkleProof.sol from any sources; imported from /Users/cgewecke/code/oz-merkle-support/contracts/MyContract.sol
    at /usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-resolver/index.js:76:1
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/async/internal/onlyOnce.js:12:1
    at next (/usr/local/lib/node_modules/truffle/build/webpack:/~/async/whilst.js:68:1)
    at /usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-resolver/index.js:64:1
    at /usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-resolver/fs.js:85:1
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/async/internal/once.js:12:1
    at replenish (/usr/local/lib/node_modules/truffle/build/webpack:/~/async/internal/eachOfLimit.js:61:1)
    at iterateeCallback (/usr/local/lib/node_modules/truffle/build/webpack:/~/async/internal/eachOfLimit.js:50:1)
    at /usr/local/lib/node_modules/truffle/build/webpack:/~/async/internal/onlyOnce.js:12:1
    at ReadFileContext.callback (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-resolver/fs.js:81:1)
    at FSReqCallback.readFileAfterOpen [as oncomplete] (fs.js:256:13)

Would be helpful if you could show an error stack trace referencing ethereumjs-util in this issue and indicate which part of your reproduction case triggers it.

[naszam]

Sorry OpenZeppelin wasn't included.
Just committed!

[naszam]

Thanks @alcuadrado! 🙌