JSPM

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  • License MIT

Compute hash of Javascript object having optional Merkle hash tags

Package Exports

    This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (merkle-json) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

    Readme

    merkle-json

    Computing the hash of JSON objects can be tricky because JSON.stringify() does not have a guaranteed string representation of a Javascript object. Specifically, the following are equivalent and valid outputs of JSON.stringify():

    var json = "{size:{w:100,h:200}}";
    var json = "{size:{h:100,w:200}}";

    MerkleJson guarantees a unique hash code for any Javascript object. In addition, MerkleJson is efficient in that it only recalculates object hashes if the object has no Merkle hash tag. If a Merkle hash tag is present, its value is returned as the hash value of that object.

    Serialize JSON object

    Unlike JSON, MerkleJson serializes objects canonically.

    var obj = {
        d:4,
        b:2,
        a:1,
        c:3,
    };
    console.log(JSON.stringify(obj)); // {"d":4,"b":2,"a":1,"c":3}
    var mj = new MerkleJson();
    console.log(mj.stringify(obj)); // {"a":1,"b":2,"c":3,"d":4}

    Compute hash of JSON object

    var mj = new MerkleJson();
    var hash = mj.hash({
        size:{
            w:100,
            h:200
        }
    }); // e77b735125fec27a61c6f54b17fb6221
    
    var hash = mj.hash({
        size:{ // hash is independent of property order
            h:200
            w:100,
        }
    }); // e77b735125fec27a61c6f54b17fb6221

    Do not calculate hash if merkleHash is present

    var mj = new MerkleJson();
    var useMerkleHash = true;
    var hash = mj.hash({
        any1: thing1, 
        any2: thing2, 
        any3: thing3, 
    }, useMerkleHash); // 441e4f8dabdc6cb17dc9500cee73155b
    
    var hash = mj.hash({
        ... // anything
        merkleHash: e77b735125fec27a61c6f54b17fb6221, 
    }, useMerkleHash); // e77b735125fec27a61c6f54b17fb6221
    
    var useMerkleHash = false; // force hash calculation
    var hash = mj.hash({
        any1: thing1, 
        any2: thing2, 
        any3: thing3, 
        merkleHash: e77b735125fec27a61c6f54b17fb6221, // ignored
    }, useMerkleHash); // 441e4f8dabdc6cb17dc9500cee73155b