随机生成字符串

    function EncodingAESKeyGen() {
        var letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
        var token = '';
        for(var i = 0; i < 43; i++) {
            var j = parseInt(Math.random() * 61 + 1);
            token += letters[j];
        }
        return token;
    }