public static string sign(string content, string privateKey, string input_charset)

        {

            Encoding code = Encoding.GetEncoding(input_charset);

            byte[] Data = code.GetBytes(content);

            RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);

            SHA1 sh = new SHA1CryptoServiceProvider();

            byte[] signData = rsa.SignData(Data, sh);

            return Convert.ToBase64String(signData);

        }

        /// <summary>

        /// Ñé֤ǩÃû

        /// </summary>

        /// <param name="content">ÐèÒªÑéÖ¤µÄÄÚÈÝ</param>

        /// <param name="signedString">Ç©Ãû½á¹û</param>

        /// <param name="publicKey">¹«Ô¿</param>

        /// <param name="input_charset">±àÂë¸ñʽ</param>

        /// <returns></returns>

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