merkle-json
v2.7.0
Published
Compute hash of Javascript object having optional Merkle hash tags
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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