方法：
// DES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; } } 示例：
string strEncrypt = Common.EncryptDES( " HelloWord ", " PengShou "); // 加密后：4BmYCZV+CyJBRcUI0LxWng== string strDecrypt = Common.DecryptDES(strEncrypt, " PengShou "); // 解密后：HelloWord