Open Source Release: js-murmur3-128

As you can imagine from of all of our blog posts about hashing that we hash a lot of things. While the various hashing algorithms may be well-defined, the devil is always in the details especially when working with multiple languages that have different ways of representing numbers. We’re happy to announce the open-source release of AK’s 128bit Murmur3 implementation for JavaScript, js-murmur3-128. We are releasing this code under the Apache License, Version 2.0 matching our other open source offerings.

Details

The goal of the implementation is to produce a hash value that is equivalent to the C++ and Java (Guava) versions for the same input and it must be usable in the browser. (Full disclosure: we’re still working through some signed/unsigned issues between the C++ and Java/JavaScript versions. The Java and JavaScript versions match exactly.)

Usage

Java (Guava):

final int seed = 0;
final byte[] bytes = { (byte)0xDE, (byte)0xAD, (byte)0xBE, (byte)0xEF,
                       (byte)0xFE, (byte)0xED, (byte)0xFA, (byte)0xCE };
com.google.common.hash.HashFunction hashFunction = com.google.common.hash.Hashing.murmur3_128(seed);
com.google.common.hash.HashCode hashCode = hashFunction.newHasher()
       .putBytes(bytes)
       .hash();
System.err.println(hashCode.asLong());

JavaScript:

var seed = 0;
var rawKey = new ArrayBuffer(8);
    var byteView = new Int8Array(rawKey);
        byteView[0] = 0xDE; byteView[1] = 0xAD; byteView[2] = 0xBE; byteView[3] = 0xEF;
        byteView[4] = 0xFE; byteView[5] = 0xED; byteView[6] = 0xFA; byteView[7] = 0xCE;
console.log(murmur3.hash128(rawKey, seed));