方法一： //须添加对System.Web的引用 using System.Web.Security; ... /// <summary> /// SHA1加密字符串 /// </summary> /// <param name="source">源字符串</param> /// <returns>加密后的字符串</returns> public string SHA1(string source) { return FormsAuthentication.HashPasswordForStoringInConfigFile(source, "SHA1"); } /// <summary> /// MD5加密字符串 /// </summary> /// <param name="source">源字符串</param> /// <returns>加密后的字符串</returns> public string MD5(string source) { return FormsAuthentication.HashPasswordForStoringInConfigFile(source, "MD5");; } using System.Security.Cryptography; ... public string Encode(string data) { byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64); byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64); DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider(); int i = cryptoProvider.KeySize; MemoryStream ms = new MemoryStream(); CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write); StreamWriter sw = new StreamWriter(cst); sw.Write(data); sw.Flush(); cst.FlushFinalBlock(); sw.Flush(); return Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length); } public string Decode(string data) { byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64); byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64); byte[] byEnc; try { byEnc = Convert.FromBase64String(data); } catch { return null; } DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider(); MemoryStream ms = new MemoryStream(byEnc); CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read); StreamReader sr = new StreamReader(cst); return sr.ReadToEnd(); }方法三(MD5不可逆)： using System.Security.Cryptography; ... //MD5不可逆加密 //32位加密 public string GetMD5_32(string s, string _input_charset) { MD5 md5 = new MD5CryptoServiceProvider(); byte[] t = md5.ComputeHash(Encoding.GetEncoding(_input_charset).GetBytes(s)); StringBuilder sb = new StringBuilder(32); for (int i = 0; i < t.Length; i++) { sb.Append(t[i].ToString("x").PadLeft(2, ‘0‘)); } return sb.ToString(); } //16位加密 public static string GetMd5_16(string ConvertString) { MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider(); string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)), 4, 8); t2 = t2.Replace("-", ""); return t2; }方法四(对称加密)： using System.IO; using System.Security.Cryptography; ... private SymmetricAlgorithm mobjCryptoService; private string Key; /// <summary> /// 对称加密类的构造函数 /// </summary> public SymmetricMethod() { mobjCryptoService = new RijndaelManaged(); Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7"; } /// <summary> /// 获得密钥 /// </summary> /// <returns>密钥</returns> private byte[] GetLegalKey() { string sTemp = Key; mobjCryptoService.GenerateKey(); byte[] bytTemp = mobjCryptoService.Key; int KeyLength = bytTemp.Length; if (sTemp.Length > KeyLength) sTemp = sTemp.Substring(0, KeyLength); else if (sTemp.Length < KeyLength) sTemp = sTemp.PadRight(KeyLength, ‘ ‘); return ASCIIEncoding.ASCII.GetBytes(sTemp); } /// <summary> /// 获得初始向量IV /// </summary> /// <returns>初试向量IV</returns> private byte[] GetLegalIV() { string sTemp = "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk"; mobjCryptoService.GenerateIV(); byte[] bytTemp = mobjCryptoService.IV; int IVLength = bytTemp.Length; if (sTemp.Length > IVLength) sTemp = sTemp.Substring(0, IVLength); else if (sTemp.Length < IVLength) sTemp = sTemp.PadRight(IVLength, ‘ ‘); return ASCIIEncoding.ASCII.GetBytes(sTemp); } /// <summary> /// 加密方法 /// </summary> /// <param name="Source">待加密的串</param> /// <returns>经过加密的串</returns> public string Encrypto(string Source) { byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source); MemoryStream ms = new MemoryStream(); mobjCryptoService.Key = GetLegalKey(); mobjCryptoService.IV = GetLegalIV(); ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor(); CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write); cs.Write(bytIn, 0, bytIn.Length); cs.FlushFinalBlock(); ms.Close(); byte[] bytOut = ms.ToArray(); return Convert.ToBase64String(bytOut); } /// <summary> /// 解密方法 /// </summary> /// <param name="Source">待解密的串</param> /// <returns>经过解密的串</returns> public string Decrypto(string Source) { byte[] bytIn = Convert.FromBase64String(Source); MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length); mobjCryptoService.Key = GetLegalKey(); mobjCryptoService.IV = GetLegalIV(); ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor(); CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read); StreamReader sr = new StreamReader(cs); return sr.ReadToEnd(); }方法五： using System.IO; using System.Security.Cryptography; using System.Text; ... //默认密钥向量 private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF }; /// <summary> /// DES加密字符串 /// </summary> /// <param name="encryptString">待加密的字符串</param> /// <param name="encryptKey">加密密钥,要求为8位</param> /// <returns>加密成功返回加密后的字符串，失败返回源串</returns> public static string EncryptDES(string encryptString, string encryptKey) { try { byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8)); byte[] rgbIV = Keys; byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString); DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider(); MemoryStream mStream = new MemoryStream(); CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write); cStream.Write(inputByteArray, 0, inputByteArray.Length); cStream.FlushFinalBlock(); return Convert.ToBase64String(mStream.ToArray()); } catch { return encryptString; } } /// <summary> /// DES解密字符串 /// </summary> /// <param name="decryptString">待解密的字符串</param> /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param> /// <returns>解密成功返回解密后的字符串，失败返源串</returns> public static string DecryptDES(string decryptString, string decryptKey) { try { byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey); byte[] rgbIV = Keys; byte[] inputByteArray = Convert.FromBase64String(decryptString); DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider(); MemoryStream mStream = new MemoryStream(); CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write); cStream.Write(inputByteArray, 0, inputByteArray.Length); cStream.FlushFinalBlock(); return Encoding.UTF8.GetString(mStream.ToArray()); } catch { return decryptString; } }方法六(文件加密)： using System.IO; using System.Security.Cryptography; using System.Text; ... //加密文件 private static void EncryptData(String inName, String outName, byte[] desKey, byte[] desIV) { //Create the file streams to handle the input and output files. FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read); FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write); fout.SetLength(0); //Create variables to help with read and write. byte[] bin = new byte[100]; //This is intermediate storage for the encryption. long rdlen = 0; //This is the total number of bytes written. long totlen = fin.Length; //This is the total length of the input file. int len; //This is the number of bytes to be written at a time. DES des = new DESCryptoServiceProvider(); CryptoStream encStream = new CryptoStream(fout, des.CreateEncryptor(desKey, desIV), CryptoStreamMode.Write); //Read from the input file, then encrypt and write to the output file. while (rdlen < totlen) { len = fin.Read(bin, 0, 100); encStream.Write(bin, 0, len); rdlen = rdlen + len; } encStream.Close(); fout.Close(); fin.Close(); } //解密文件 private static void DecryptData(String inName, String outName, byte[] desKey, byte[] desIV) { //Create the file streams to handle the input and output files. FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read); FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write); fout.SetLength(0); //Create variables to help with read and write. byte[] bin = new byte[100]; //This is intermediate storage for the encryption. long rdlen = 0; //This is the total number of bytes written. long totlen = fin.Length; //This is the total length of the input file. int len; //This is the number of bytes to be written at a time. DES des = new DESCryptoServiceProvider(); CryptoStream encStream = new CryptoStream(fout, des.CreateDecryptor(desKey, desIV), CryptoStreamMode.Write); //Read from the input file, then encrypt and write to the output file. while (rdlen < totlen) { len = fin.Read(bin, 0, 100); encStream.Write(bin, 0, len); rdlen = rdlen + len; } encStream.Close(); fout.Close(); fin.Close(); }using System;using System.Security.Cryptography;//这个是处理文字编码的前提using System.Text;using System.IO;/// <summary>/// DES加密方法/// </summary>/// <param name="strPlain">明文</param>/// <param name="strDESKey">密钥</param>/// <param name="strDESIV">向量</param>/// <returns>密文</returns>public string DESEncrypt(string strPlain,string strDESKey,string strDESIV){ //把密钥转换成字节数组 byte[] bytesDESKey=ASCIIEncoding.ASCII.GetBytes(strDESKey); //把向量转换成字节数组 byte[] bytesDESIV=ASCIIEncoding.ASCII.GetBytes(strDESIV); //声明1个新的DES对象 DESCryptoServiceProvider desEncrypt=new DESCryptoServiceProvider(); //开辟一块内存流 MemoryStream msEncrypt=new MemoryStream(); //把内存流对象包装成加密流对象 CryptoStream csEncrypt=new CryptoStream(msEncrypt,desEncrypt.CreateEncryptor(bytesDESKey,bytesDESIV),CryptoStreamMode.Write); //把加密流对象包装成写入流对象 StreamWriter swEncrypt=new StreamWriter(csEncrypt); //写入流对象写入明文 swEncrypt.WriteLine(strPlain); //写入流关闭 swEncrypt.Close(); //加密流关闭 csEncrypt.Close(); //把内存流转换成字节数组，内存流现在已经是密文了 byte[] bytesCipher=msEncrypt.ToArray(); //内存流关闭 msEncrypt.Close(); //把密文字节数组转换为字符串，并返回 return UnicodeEncoding.Unicode.GetString(bytesCipher);}/// <summary>/// DES解密方法/// </summary>/// <param name="strCipher">密文</param>/// <param name="strDESKey">密钥</param>/// <param name="strDESIV">向量</param>/// <returns>明文</returns>public string DESDecrypt(string strCipher,string strDESKey,string strDESIV){ //把密钥转换成字节数组 byte[] bytesDESKey=ASCIIEncoding.ASCII.GetBytes(strDESKey); //把向量转换成字节数组 byte[] bytesDESIV=ASCIIEncoding.ASCII.GetBytes(strDESIV); //把密文转换成字节数组 byte[] bytesCipher=UnicodeEncoding.Unicode.GetBytes(strCipher); //声明1个新的DES对象 DESCryptoServiceProvider desDecrypt=new DESCryptoServiceProvider(); //开辟一块内存流，并存放密文字节数组 MemoryStream msDecrypt=new MemoryStream(bytesCipher); //把内存流对象包装成解密流对象 CryptoStream csDecrypt=new CryptoStream(msDecrypt,desDecrypt.CreateDecryptor(bytesDESKey,bytesDESIV),CryptoStreamMode.Read); //把解密流对象包装成读出流对象 StreamReader srDecrypt=new StreamReader(csDecrypt); //明文=读出流的读出内容 string strPlainText=srDecrypt.ReadLine(); //读出流关闭 srDecrypt.Close(); //解密流关闭 csDecrypt.Close(); //内存流关闭 msDecrypt.Close(); //返回明文 return strPlainText;}原文：http://www.cnblogs.com/liuyl/p/4276451.html