C#-XML文件及字符串的加密解密代码

先看XML文件的加解密，例如在桌面有个Student.xml文档，包含学生信息，需进行加密处理：

开始代码，添加命名空间引用：

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1 2	using System.Security.Cryptography; using System.Security.Cryptography.Xml;

建立一个静态类，并声明变量：

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const string path = @"C:\Users\HKL\Desktop\Student.xml";//文件路径 static XmlDocument doc; static XMLEncypt() {      doc = new XmlDocument(); }

编写创建算法函数，用以解加密：　　

        /// <summary>
        /// 返回加密算法及类型
        /// </summary>
        /// <param name="method"></param>
        /// <returns></returns>
        static SymmetricAlgorithm Create(out string method)
        {
            RijndaelManaged TDESKey = new RijndaelManaged();
            TDESKey.Key = Encoding.Unicode.GetBytes("0123456789012345");
            TDESKey.Mode = CipherMode.ECB;
            TDESKey.Padding = PaddingMode.PKCS7;
            switch (TDESKey.KeySize)
            {
                case 128: method = EncryptedXml.XmlEncAES128Url; break;
                case 256: method = EncryptedXml.XmlEncAES256Url; break;
                case 192: method = EncryptedXml.XmlEncAES192Url; break;
                default: method = EncryptedXml.XmlEncAES128Url; break;
            }
            return TDESKey;
        }

文件加密方法：

        public static void Encrypt()
        {
            doc.Load(path);
            XmlElement element = (doc.FirstChild is XmlDeclaration ? doc.FirstChild.NextSibling : doc.FirstChild) as XmlElement;
            if (element == null || element.Name == "EncryptedData")
                return;
            EncryptedXml eXML = new EncryptedXml(doc);
            string method;
            byte[] outPut = eXML.EncryptData(element, Create(out method), false);
            EncryptedData eData = new EncryptedData()
            {
                Type = EncryptedXml.XmlEncElementUrl,
                EncryptionMethod = new EncryptionMethod(method),
                CipherData = new CipherData()
                {
                    CipherValue = outPut,
                }
            };
            EncryptedXml.ReplaceElement(element, eData, false);
            doc.Save(path);
        }

文件解密方法：

        public static void Decrypt()
        {
            doc.Load(path);
            XmlElement element = doc.GetElementsByTagName("EncryptedData")[0] as XmlElement;
            if (element == null)
                return;
            EncryptedData eData = new EncryptedData();
            eData.LoadXml(element);
            EncryptedXml eXML = new EncryptedXml();
            string method;
            byte[] outPut = eXML.DecryptData(eData, Create(out method));
            eXML.ReplaceData(element, outPut);
            doc.Save(path);
        }

*若只是读取加密文件，不对文件进行修改，则解密函数中不要执行doc.Save(path)即可；

*若要对加密文件进行修改，需先Load文件->解密内容->修改内容->加密内容->保存；

*若新增加密文件，先生成成XmlDoc结构，再进行加密并保存。

        public static void Modify()
        {
            //*****************************************解密
            doc.Load(path);
            XmlElement element = doc.GetElementsByTagName("EncryptedData")[0] as XmlElement;
            if (element == null)
                return;
            EncryptedData eData = new EncryptedData();
            eData.LoadXml(element);
            EncryptedXml eXML = new EncryptedXml();
            string method;
            byte[] outPut = eXML.DecryptData(eData, Create(out method));
            eXML.ReplaceData(element, outPut);
            //******************************************修改
            XmlNodeList nodes = doc.SelectNodes("Students/Student");
            foreach (XmlNode node in nodes)
            {
                foreach (XmlAttribute attr in node.Attributes)
                {
                    if (attr.Name == "Age")
                        attr.Value = (Convert.ToSingle(attr.Value) + 1).ToString();
                }
            }
            //*****************************************加密
            element = (doc.FirstChild is XmlDeclaration ? doc.FirstChild.NextSibling : doc.FirstChild) as XmlElement;
            if (element == null || element.Name == "EncryptedData")
                return;
            eXML = new EncryptedXml(doc);
            outPut = eXML.EncryptData(element, Create(out method), false);
            eData = new EncryptedData()
            {
                Type = EncryptedXml.XmlEncElementUrl,
                EncryptionMethod = new EncryptionMethod(method),
                CipherData = new CipherData()
                {
                    CipherValue = outPut,
                }
            };
            EncryptedXml.ReplaceElement(element, eData, false);
            doc.Save(path);
        }

效果：

下面记录字符串文本的加解密功能，ReadStr函数将txt文件中文本读出：

        static string ReadStr()
        {
            sr = new StreamReader(path);
            StringBuilder sb = new StringBuilder();
            while (true)
            {
                string str = sr.ReadLine();
                if (str == null)
                    break;
                sb.Append(str + "\r\n");
            }
            sr.Close();
            return sb.ToString();
        }

加密解密方法：

        public static void Encrypt()//加密
        {
            string val = ReadStr();
            ICryptoTransform crypt = Create().CreateEncryptor();
            byte[] old = Encoding.Default.GetBytes(val);
            byte[] cur = crypt.TransformFinalBlock(old, 0, old.Length);
            string curStr = Convert.ToBase64String(cur);
            sw = new StreamWriter(path, false);
            sw.Write(curStr);
            sw.Close();
        }

        public static void Decrypt()//解密
        {
            string val = ReadStr();
            ICryptoTransform crypt = Create().CreateDecryptor();
            byte[] old = Convert.FromBase64String(val);
            byte[] cur = crypt.TransformFinalBlock(old, 0, old.Length);
            string curStr = Encoding.Default.GetString(cur);
            sw = new StreamWriter(path, false);
            sw.Write(curStr);
            sw.Close();
        }