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   简介

                 本文基于.NET的C#实现3DES算法的加密和解密过程。可以用在加密软件、加密狗等。          代码下载链接：https://download.csdn.net/download/C_gyl/88487942

使用

  第一种方法

   加密

1. KeySize：128(16字节)，192（24字节）。
2. Key： TripleDES 算法的密钥。

        public static string Encrypt3DES(string str, string key){try{TripleDESCryptoServiceProvider DES = new TripleDESCryptoServiceProvider();DES.KeySize = 128;DES.Key = Encoding.UTF8.GetBytes(key);DES.Mode = CipherMode.ECB;DES.Padding = PaddingMode.Zeros;ICryptoTransform DESEncrypt = DES.CreateEncryptor();byte[] Buffer = Encoding.UTF8.GetBytes(str);return ToHexString(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length), str.Length);}catch (Exception ex) { return ex.Message; }}

 解密

        public static string Decrypt3DES(string str, string key){try{TripleDESCryptoServiceProvider DES = new TripleDESCryptoServiceProvider();DES.Key = Encoding.UTF8.GetBytes(key);DES.Mode = CipherMode.ECB;DES.Padding = PaddingMode.Zeros;ICryptoTransform DESDecrypt = DES.CreateDecryptor();byte[] Buffer = HexGetBytes(str);byte[] Destxt = DESDecrypt.TransformFinalBlock(Buffer, 0, Buffer.Length);return Encoding.UTF8.GetString(Destxt, 0, Destxt.Length);}catch (Exception ex) { return ex.Message; }}

  转换

        // byte[]转16进制格式string 0xae00cf => "AE00CF "private static string ToHexString(byte[] bytes, int length){string hexString = string.Empty;if (bytes != null){StringBuilder strB = new StringBuilder();if (length == 0) { length = bytes.Length; }for (int i = 0; i < length; i++){strB.Append(bytes[i].ToString("X2"));}hexString = strB.ToString();} return hexString;}//16进制转byte[]   0x0a => 10private static byte[] HexGetBytes(string hexString){int discarded = 0;string newString = "";char c;// remove all none A-F, 0-9, charactersfor (int i = 0; i < hexString.Length; i++){c = hexString[i];if (Uri.IsHexDigit(c))newString += c;elsediscarded++;}// if odd number of characters, discard last characterif (newString.Length % 2 != 0){discarded++;newString = newString.Substring(0, newString.Length - 1);}int byteLength = newString.Length / 2;byte[] bytes = new byte[byteLength];string hex;int j = 0;for (int i = 0; i < bytes.Length; i++){hex = new String(new Char[] { newString[j], newString[j + 1] });bytes[i] = HexToByte(hex);j = j + 2;}return bytes;}private static byte HexToByte(string hex){byte tt = byte.Parse(hex, System.Globalization.NumberStyles.HexNumber);return tt;}

  第二种方法

1. 第一种方法有个弊端是.Net会对密钥Key进行判断，例如key="0000000000000000"，会有报警"指定密钥是“TripleDES”的已知弱密钥，不能使用。" .Net方法（TripleDES.IsWeakKey），它检查3DES密钥的弱点。
2. 解释弱密钥参考：Decrypting TripleDES：指定的密钥是已知的弱密钥，不能使用 - VoidCC
3. 破解若密钥参考：https://www.cnblogs.com/jintianhu/archive/2011/11/26/2264375.html

  加密

        public static string DESEncrypt(string str, string key){try{TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();des.Padding = PaddingMode.Zeros;byte[] keyByte = Encoding.UTF8.GetBytes(key);Type t = Type.GetType("System.Security.Cryptography.CryptoAPITransformMode");object obj = t.GetField("Encrypt", BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly).GetValue(t);MethodInfo mi = des.GetType().GetMethod("_NewEncryptor", BindingFlags.Instance | BindingFlags.NonPublic);ICryptoTransform desCrypt = (ICryptoTransform)mi.Invoke(des, new object[] { keyByte, CipherMode.ECB, null, 0, obj });byte[] Buffer = Encoding.UTF8.GetBytes(str);byte[] result = desCrypt.TransformFinalBlock(Buffer, 0, Buffer.Length);return BitConverter.ToString(result).Replace("-", "");}catch (Exception ex) { return ex.Message; }}

  解密

        public static string DESDecrypt(string str, string key){try{TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();des.Padding = PaddingMode.Zeros;byte[] keyByte = Encoding.UTF8.GetBytes(key);Type t = Type.GetType("System.Security.Cryptography.CryptoAPITransformMode");object obj = t.GetField("Decrypt", BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly).GetValue(t);MethodInfo mi = des.GetType().GetMethod("_NewEncryptor", BindingFlags.Instance | BindingFlags.NonPublic);ICryptoTransform desCrypt = (ICryptoTransform)mi.Invoke(des, new object[] { keyByte, CipherMode.ECB, null, 0, obj });byte[] Buffer = HexGetBytes(str);byte[] Destxt = desCrypt.TransformFinalBlock(Buffer, 0, Buffer.Length);return Encoding.UTF8.GetString(Destxt, 0, Destxt.Length);}catch (Exception ex) { return ex.Message; }}

结果 

        static void Main(string[] args){string str = "12345678";//长度是8的倍数string key = "1234567812345678"; //长度是16或24//第一种方法//有密钥检测//"指定密钥是“TripleDES”的已知弱密钥，不能使用。"string strEncrypt1 = Encrypt3DES(str, key);System.Console.WriteLine("加密结果1：" + strEncrypt1);string strDecrypt1 = Decrypt3DES(strEncrypt1, key);System.Console.WriteLine("解密结果1：" + strDecrypt1);//第二种方法//无弱密钥检测string strEncrypt2 = DESEncrypt(str, key);System.Console.WriteLine("加密结果2：" + strEncrypt2);string strDecrypt2 = DESDecrypt(strEncrypt2, key);System.Console.WriteLine("解密结果2：" + strDecrypt2);Console.ReadKey();}

 key = "1234567890123456"

 key = "1234567812345678"