function (opt) {

        if (!opt.SecretId) return console.error('missing param SecretId');
        if (!opt.SecretKey) return console.error('missing param SecretKey');

        if (opt.Version === '4.0') {
            return CosAuthV4(opt);
        }

        opt = opt || {};

        var SecretId = opt.SecretId;
        var SecretKey = opt.SecretKey;
        var method = (opt.Method || 'get').toLowerCase();
        var query = opt.Query || {};
        var headers = opt.Headers || {};
        var pathname = opt.Pathname || '/';
        var expires = opt.Expires;

        var getObjectKeys = function (obj) {
            var list = [];
            for (var key in obj) {
                if (obj.hasOwnProperty(key)) {
                    list.push(key);
                }
            }
            return list.sort(function (a, b) {
                a = a.toLowerCase();
                b = b.toLowerCase();
                return a === b ? 0 : (a > b ? 1 : -1);
            });
        };

        var obj2str = function (obj) {
            var i, key, val;
            var list = [];
            var keyList = getObjectKeys(obj);
            for (i = 0; i < keyList.length; i++) {
                key = keyList[i];
                val = (obj[key] === undefined || obj[key] === null) ? '' : ('' + obj[key]);
                key = key.toLowerCase();
                key = camSafeUrlEncode(key);
                val = camSafeUrlEncode(val) || '';
                list.push(key + '=' + val)
            }
            return list.join('&');
        };

        // 签名有效起止时间
        var now = parseInt(new Date().getTime() / 1000) - 1;
        var exp = now + (expires === undefined ? 900 : (expires * 1 || 0)); // 默认签名过期时间为当前时间 + 900s

        // 要用到的 Authorization 参数列表
        var qSignAlgorithm = 'sha1';
        var qAk = SecretId;
        var qSignTime = now + ';' + exp;
        var qKeyTime = now + ';' + exp;
        var qHeaderList = getObjectKeys(headers).join(';').toLowerCase();
        var qUrlParamList = getObjectKeys(query).join(';').toLowerCase();

        // 签名算法说明文档：https://www.qcloud.com/document/product/436/7778
        // 步骤一：计算 SignKey
        var signKey = CryptoJS.HmacSHA1(qKeyTime, SecretKey).toString();

        // 步骤二：构成 FormatString
        var formatString = [method, pathname, obj2str(query), obj2str(headers), ''].join('\n');

        // 步骤三：计算 StringToSign
        var stringToSign = ['sha1', qSignTime, CryptoJS.SHA1(formatString).toString(), ''].join('\n');

        // 步骤四：计算 Signature
        var qSignature = CryptoJS.HmacSHA1(stringToSign, signKey).toString();

        // 步骤五：构造 Authorization
        var authorization = [
            'q-sign-algorithm=' + qSignAlgorithm,
            'q-ak=' + qAk,
            'q-sign-time=' + qSignTime,
            'q-key-time=' + qKeyTime,
            'q-header-list=' + qHeaderList,
            'q-url-param-list=' + qUrlParamList,
            'q-signature=' + qSignature
        ].join('&');

        return authorization;

    }