npmcomponent / satazor-sparkmd5

This repository is a mirror of the component module satazor/sparkmd5. It has been modified to work with NPM+Browserify. You can install it using the command npm install npmcomponent/satazor-sparkmd5. Please do not open issues or send pull requests against this repo. If you have issues with this repo, report it to npmcomponent.

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.

Improvements over the JKM md5 library

• 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(),
        frOnload = 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
            }
        },
        frOnerror = function () {
            console.warn("oops, something went wrong.");
        };

    function loadNext() {
        var fileReader = new FileReader();
        fileReader.onload = frOnload;
        fileReader.onerror = frOnerror;

        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, handling UTF8 automatically.

SparkMD5#appendBinary(str)

Appends a binary string.

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#destroy()

Releases memory used by the incremental buffer and other aditional 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, 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 aditional resources.

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)