Match web3py hashing function to solidity hashing function

Question

If I am using web3py to hash some data, like so,

msgHash = w3.soliditySha3(['bytes32','bytes32'], [dataBytes, saltBytes]);

What would be the correct way to hash inside of a Solidity contract and expect the same resultant hash?

In Solidity (v0.4.24) I have tried,

keccak256(abi.encodePacked(data, salt))

sha3(data, salt)

and a few other ways but no luck. I believe there is a specific way to do this and the exact hashing algorithms don't always match. In Solidity the data type I am using is,

bytes32

Could the text= prefix be messing this up? Also is there a specific prefix that Solidity uses?

dataBytes = w3.toBytes(text=data);
saltBytes = w3.toBytes(text=salt);

Answer 1

The issue is how you manage the text. You can do:

data = 'some data';
salt = 'some salt data';      
msgHash = w3.soliditySha3(['bytes32','bytes32'], [bytes(data.encode()), bytes(salt.encode())]);

In solidity:

string memory data = 'some data';
string memory salt = 'some salt data';
hash = keccak256(abi.encodePacked(data,salt));

This will produce the same hash.

If you have for instance int256 there should be no problem:

data = 'some data';
salt = 1234567;      
msgHash = w3.soliditySha3(['bytes32','int256'], [bytes(data.encode()), salt]);

Hope this helps