SparkMD5

SparkMD5 is a fast md5 implementation of the MD5 algorithm. This script is based in the JKM md5 library which is the fastest algorithm around. This is most suitable for browser usage, because nodejs version might be faster.

NOTE: Please disable Firebug while performing the test! Firebug consumes a lot of memory and CPU and slows the test by a great margin.

Demo

Install

npm install --save spark-md5

Improvements over the JKM md5 library

• Strings are converted to utf8, like most server side algorithms
• Fix computation for large amounts of data (overflow)
• Incremental md5 (see below)
• Support for array buffers (typed arrays)
• Functionality wrapped in a closure, to avoid global assignments
• Object oriented library
• CommonJS (it can be used in node) and AMD integration
• Code passed through JSHint and JSCS

Incremental md5 performs a lot better for hashing large amounts of data, such as files. One could read files in chunks, using the FileReader & Blob's, and append each chunk for md5 hashing while keeping memory usage low. See example below.

Usage

Normal usage

var hexHash = SparkMD5.hash('Hi there');        // hex hash
var rawHash = SparkMD5.hash('Hi there', true);  // OR raw hash (binary string)

Incremental usage

var spark = new SparkMD5();
spark.append('Hi');
spark.append(' there');
var hexHash = spark.end();                      // hex hash
var rawHash = spark.end(true);                  // OR raw hash (binary string)

Hash a file incrementally

NOTE: If you test the code bellow using the file:// protocol in chrome you must start the browser with -allow-file-access-from-files argument. Please see: http://code.google.com/p/chromium/issues/detail?id=60889

document.getElementById('file').addEventListener('change', function () {
    var blobSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice,
        file = this.files[0],
        chunkSize = 2097152,                             // Read in chunks of 2MB
        chunks = Math.ceil(file.size / chunkSize),
        currentChunk = 0,
        spark = new SparkMD5.ArrayBuffer(),
        fileReader = new FileReader();

    fileReader.onload = function (e) {
        console.log('read chunk nr', currentChunk + 1, 'of', chunks);
        spark.append(e.target.result);                   // Append array buffer
        currentChunk++;

        if (currentChunk < chunks) {
            loadNext();
        } else {
            console.log('finished loading');
            console.info('computed hash', spark.end());  // Compute hash
        }
    };

    fileReader.onerror = function () {
        console.warn('oops, something went wrong.');
    };

    function loadNext() {
        var start = currentChunk * chunkSize,
            end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize;

        fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));
    }

    loadNext();
});