javascriptcryptographysjcl

Good Stanford Javascript Crypto Library (SJCL) examples? (JS cryptography)


I am looking at a way to do client-side cryptography in Javascript (keeping http://www.matasano.com/articles/javascript-cryptography/ in mind) and have found SJCL. But I seem unable to find good code examples for it. Any pointers?


Solution

  • I did a presentation last year titled Developer's Guide to JavaScript and Web Cryptography and have the demo site online at https://jswebcrypto.azurewebsites.net/

    This includes simple Hash, HMAC, PBKDF2 and AES examples for OpenSSL command line (as a baseline) SJCL, CryptoJS, Node.js Crypto, and even W3C Web Cryptography API

    Here are the SJCL examples:

    Hash

    var out = sjcl.hash.sha1.hash("The quick brown fox jumps over the lazy dog");
    var hash = sjcl.codec.hex.fromBits(out)
    // "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12"
    

    HMAC

    var key = sjcl.codec.utf8String.toBits("key");
    var out = (new sjcl.misc.hmac(key, sjcl.hash.sha256)).mac("The quick brown fox jumps over the lazy dog");
    var hmac = sjcl.codec.hex.fromBits(out)
    // "f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8"
    

    PBKDF2

    var hmacSHA1 = function (key) {
        var hasher = new sjcl.misc.hmac( key, sjcl.hash.sha1 );
        this.encrypt = function () {
            return hasher.encrypt.apply( hasher, arguments );
        };
    };
    
    var passwordSalt = sjcl.codec.hex.toBits( "cf7488cd1e48e84990f51b3f121e161318ba2098aa6c993ded1012c955d5a3e8" );
    var derivedKey = sjcl.misc.pbkdf2( "password", passwordSalt, 100, 256, hmacSHA1 );
    var hexKey = sjcl.codec.hex.fromBits( derivedKey );
    // c12b2e03a08f3f0d23f3c4429c248c275a728814053a093835e803bc8e695b4e
    

    Note: This requires you in include sha1.js in addition to sjcl.js.