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 (see: http://jsperf.com/md5-shootout/7). 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

Improvements over the JKM md5 library

• Fix computation for large amounts of data (overflow)
• Functionality wrapped in a closure
• Object oriented library
• Incremental md5 (see bellow)
• Support for array buffers (typed arrays)
• CommonJS (it can be used in node) and AMD integration
• Validates using jshint

Incremental md5 performs a lot better for hashing large ammounts 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 bellow.

Usage

Normal usage

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

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

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();
});

You can see some more examples in the test folder.

Documentation

SparkMD5 class

SparkMD5#append(str)

Appends a string.

SparkMD5#appendBinary(str)

Appends a binary string (e.g.: string returned from the deprecated readAsBinaryString).

SparkMD5#end(raw)

Finishes the computation of the md5, returning the hex result. If raw is true, the raw result will be returned instead.

SparkMD5#reset()

Resets the internal state of the computation.

SparkMD5#getState()

Returns an object representing the internal computation state. You can pass this state to setState(). This feature is useful to resume an incremental md5.

SparkMD5#setState(state)

Sets the internal computation state. See: getState().

SparkMD5#destroy()

Releases memory used by the incremental buffer and other additional resources.

SparkMD5.hash(str, raw)

Hashes a string directly, returning the hex result. If raw is true, the raw result will be returned instead. Note that this function is static.

SparkMD5.hashBinary(str, raw)

Hashes a binary string directly (e.g.: string returned from the deprecated readAsBinaryString), returning the hex result. If raw is true, the raw result will be returned instead. Note that this function is static.

SparkMD5.ArrayBuffer class

SparkMD5.ArrayBuffer#append(arr)

Appends an array buffer.

SparkMD5.ArrayBuffer#end(raw)

Finishes the computation of the md5, returning the hex result. If raw is true, the raw result will be returned instead.

SparkMD5.ArrayBuffer#reset()

Resets the internal state of the computation.

SparkMD5.ArrayBuffer#destroy()

Releases memory used by the incremental buffer and other additional resources.

SparkMD5.ArrayBuffer#getState()

Returns an object representing the internal computation state. You can pass this state to setState(). This feature is useful to resume an incremental md5.

SparkMD5.ArrayBuffer#setState(state)

Sets the internal computation state. See: getState().

SparkMD5.ArrayBuffer.hash(arr, raw)

Hashes an array buffer directly, returning the hex result. If raw is true, the raw result will be returned instead. Note that this function is static.

Credits

Joseph Myers (http://www.myersdaily.org/joseph/javascript/md5-text.html)