Sha256 Hash from Solidity Smart Contract doesn't match web3.js Hash

Question

I'm struggling to match two hashes. I hash a Json in String format in my Smart Contract like this.

   function verifyProof(string calldata _fullProof) public returns(bool r){
        bytes32 hashed = keccak256(abi.encodePacked(_fullProof));
         ....
         ...}

I'm interacting with the Smart Contract via a external Truffle Script that I execute with the command "truffle exec truffle_script.js

In the Script I've been trying various methods to archive the same hash:

    const hashedLocal = web3.utils.soliditySha3(web3.utils.encodePacked(JSON.stringify(proof)));
    console.log("hashed local2", hashedLocal)
    console.log("hashed local3",web3.utils.keccak256(web3.utils.encodePacked(toString(proof))));
   console.log("hashed local3.5", web3.utils.keccak256(proof));
   console.log("hashed local4", web3.utils.keccak256(JSON.stringify(proof)));
   console.log("hashed local4", web3.utils.keccak256(toString(proof)));
   console.log("hashed local5" ,web3.utils.soliditySha3({t: 'string', v: proof}));
   console.log("hashed local6" ,web3.utils.soliditySha3({t: 'string', v: toString(proof)}));
   console.log("hashed local7" ,web3.utils.soliditySha3(web3.utils.toHex(proof) ));

I simply can't produce the same hash.

Does anybody have an idea what the problem might be?

The data to hash looks like this:

{"proof": {
    "a": [
      "0x2010f7ceeb118735d309ff1ab4410d77437d6643270f341f2e5b9b9674f32317",
      "0x11f580342e8543a21365e088ef337079fbd0e73c5cb1ae17d9d291ed042c33bf"
    ],"b": [
      [
        "0x1562eac9e8e36fab1c5784ba2097686c4bdfbfe232ed10cd5efc0eb9f62bee63",
        "0x306098b792f0e79e945a4ff60ae7c5406b0b58850e4ed5bbe42f08b7efc85734"
      ],
      [
        "0x27f016473a580620fc2ef45c0541d35b425de6ebac1c78006a39ba286b6b9afb",
        "0x1ab7506590ee8060b83324b8e71f6db79805d04fa10b949c9cada2692c15b47d"
      ]
    ],"c": [
      "0x2b12f5aa5257e7356cd5aee36950e7af9914efca8eaeeed8958f9fabf9f54032",
      "0x27fd7a495856d6ef3b05c9920b03b5c05f1ac90bfae28f32a8db154cc7f7978d"
    ]
  },
"inputs": [
    "0x00000000000000000000000000000000779d99147b3605d185eb5f9d017ef1ae",
    "0x00000000000000000000000000000000e1c0538dd9730a859f8f2c8ca2001e04"
  ]
}

Answer 1

here is the solidity code:

    function hash(string calldata data) public pure returns(bytes32){
        return keccak256(abi.encodePacked(data));
    }

and here is JS code:

console.log(web3.utils.keccak256("hello"))

these two codes return similar data for "hello" as input. I think you problem is inputs for these two functions, check you inputs and try simple inputs and check for uppercase and lowercase letters.