Yahoo! UI Library

/**
 * Contains helper methods for Cryptographic functions
 * @module crypto
 */

/**
 * @class Crypto
 */
var _C = Y.Crypto || { };

Y.mix(_C, {
    /**
     * Adds two numerics as if they were 32-bit integers.
     *
     * @method add32Bit
     *
     * @param {int} first operand
     * @param {int} second operand
     *
     * @static
     */
    add32Bit: function (x,y) {
        return (x  + y) & 0xffffffff;
    },
  /**
     * Converts a standard JavaScript string (utf16) to a UTF8 string
     *
     * @method utf16ToUtf8
     *
     * @param {string} The utf16 encoded string to convert to a utf8 array
     *
     * @static
     */
    utf16ToUtf8: function(string) {
        var output = "", cd, pr, i = 0;

        while (i < string.length) {
            cd = string.charCodeAt(i);
            pr = i + 1 < string.length ? string.charCodeAt(i + 1) : 0;

            if (0xd800 <= cd && cd <= 0xdbff && 0xdc00 <= pr && pr <= 0xdfff) {
                // Surrogate Pair
                cd = 0x10000 + ((cd & 0x3ff) + (pr & 0x03ff));
                i += 1;
            }

            if (cd <= 0x007f) {
                output += String.fromCharCode(cd);
            } else if (cd <= 0x07ff) {
                output += String.fromCharCode(0xc0 | ((cd >>> 6) & 15),
                                                                            0x80 |  (cd & 63));
            } else if (cd <= 0xffff) {
                output += String.fromCharCode(0xe0 | ((cd >>> 12) & 15 ),
                                                                            0x80 | ((cd >>>  6) & 63),
                                                                            0x80 |  (cd & 63));
            } else if (cd <= 0x1fffff) {
                output += String.fromCharCode(0xf0 | ((cd >>> 18) & 15),
                                                                            0x80 | ((cd >>> 12) & 63),
                                                                            0x80 | ((cd >>>  6) & 63),
                                                                            0x80 |  (cd & 63));
            }
            i += 1;
        }
        return output;
    },
    /**
     * Converts a utf8 encoded string to a byte array. It's important to use a
     * utf8 encoded string, because otherwise characters with individual bytes
     * greater than 255 will be silently dropped.
     *
     * @method utf8ToByteArray
     *
     * @param {string} The utf8 encoded string to convert to a byte array
     *
     * @static
     */
    utf8ToByteArray: function(string) {
        var output = Array(string.length >> 2), i, j;
        for (i = 0 ; i < output.length ; i += 1) { output[i] = 0; }
        for (i = 0 ; i < string.length ; i += 1) {
            j = i * 8;
            output[j >> 5] |= (string.charCodeAt(i) & 0xff) << (j % 32);
        }
        return output;
    },
    byteArrayToString: function(array) {
        var output = "", i, code;
        for (i = 0 ; i < array.length * 32 ; i += 8) {
            code = (array[i >> 5] >>> (i % 32));
            output += String.fromCharCode(code & 0xff);
        }
        return output;
    },
    utf8ToHex: function(string) {
        var output = "", i, cd, chars = "0123456789abcdef";
        for (i = 0 ; i < string.length ; i += 1) {
            cd = string.charCodeAt(i);
            output += chars.charAt(( cd >>> 4) & 0x0f) +
                              chars.charAt( cd & 0x0f);
        }
        return output;
    },
    /**
     * Converts a standard JavaScript string (utf16) to a Byte Array
     * @method stringToByteArray
     * @param {string} The utf16 encoded string to convert to a byte array
     * @static
     */
    stringToByteArray: function(string) {
        return _C.utf8ToByteArray(_C.utf16ToUtf8(string));
    }
});

Y.Crypto = _C;