| 最近收到了很多朋友的來信說希望提供DES的C#代碼，但是我個(gè)人認(rèn)為，.NET 提供了很多標(biāo)準(zhǔn)函數(shù)，沒有必要自己寫，所以我也只發(fā)布了C++的代碼，如果大家一定要熟悉加密過程的話，也可以自己動(dòng)手實(shí)現(xiàn)整個(gè)過程，這個(gè)可以參考我博客里的DES 算法介紹，和yxyDES2 Class的代碼，代碼注釋相當(dāng)?shù)那宄? .NET 提供了很多標(biāo)準(zhǔn)加密、解密函數(shù)，我簡(jiǎn)要介紹一下DES，SHA1，RSA的標(biāo)準(zhǔn)函數(shù)的使用。如果你想做一個(gè)網(wǎng)絡(luò)安全模塊，只需將三種算法結(jié)合起來設(shè)計(jì)一個(gè)模型，我相信可以實(shí)現(xiàn)很多復(fù)雜的功能。 示例本身并不復(fù)雜，我也不做過多解釋，我也學(xué)Linus Torvalds一樣吼一句："Read the f**ing code”，哈哈，開個(gè)玩笑，我相信大家肯定能看懂。 注：以下示例需引用命名空間 ： using System.Security.Cryptography; 一. DES 加密、解密 我相信一下注釋相當(dāng)清楚了，加上我博客里關(guān)于DES的文章確實(shí)不少，所以DES不做任何解釋，怎么調(diào)用就更不用解釋了吧，呵呵： //默認(rèn)密鑰向量 private byte[] Keys = { 0xEF, 0xAB, 0x56, 0x78, 0x90, 0x34, 0xCD, 0x12 }; /// <summary> /// DES加密字符串 /// </summary> /// <param name="encryptString">待加密的字符串</param> /// <param name="encryptKey">加密密鑰,要求為8位</param> /// <returns>加密成功返回加密后的字符串，失敗返回源串</returns> public 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">解密密鑰,要求為8位,和加密密鑰相同</param> /// <returns>解密成功返回解密后的字符串，失敗返源串</returns> public string DecryptDES(string decryptString, string decryptKey) { try { byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey.Substring(0, 8)); 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; } } 二. SHA1 加密 （HASH算法沒有解密） 安全哈希算法（Secure Hash Algorithm）主要適用于數(shù)字簽名標(biāo)準(zhǔn)（Digital Signature Standard DSS）里面定義的數(shù)字簽名算法（Digital Signature Algorithm DSA）。對(duì)于長(zhǎng)度小于2^64位的消息，SHA1會(huì)產(chǎn)生一個(gè)160位的消息摘要。當(dāng)接收到消息的時(shí)候，這個(gè)消息摘要可以用來驗(yàn)證數(shù)據(jù)的完整性。在傳輸?shù)倪^程中，數(shù)據(jù)很可能會(huì)發(fā)生變化，那么這時(shí)候就會(huì)產(chǎn)生不同的消息摘要。 SHA1有如下特性：不可以從消息摘要中復(fù)原信息；兩個(gè)不同的消息不會(huì)產(chǎn)生同樣的消息摘要。 代碼如下： /// <summary> /// use sha1 to encrypt string /// </summary> public string SHA1_Encrypt(string Source_String) { byte[] StrRes = Encoding.Default.GetBytes(Source_String); HashAlgorithm iSHA = new SHA1CryptoServiceProvider(); StrRes = iSHA.ComputeHash(StrRes); StringBuilder EnText = new StringBuilder(); foreach (byte iByte in StrRes) { EnText.AppendFormat("{0:x2}", iByte); } return EnText.ToString(); } 三.RSA 加密、解密 （本例來自 MSDN） RSA加密算法是一種非對(duì)稱加密算法。在公鑰加密標(biāo)準(zhǔn)和電子商業(yè)中RSA被廣泛使用。RSA是1977年由羅納德·李維斯特（Ron Rivest）、阿迪·薩莫爾（Adi Shamir）和倫納德·阿德曼（Leonard Adleman）一起提出的。當(dāng)時(shí)他們?nèi)硕荚诼槭±砉W(xué)院工作。RSA就是他們?nèi)诵帐祥_頭字母拼在一起組成的。 RSA算法的可靠性基于分解極大的整數(shù)是很困難的。假如有人找到一種很快的分解因子的算法的話，那么用RSA加密的信息的可靠性就肯定會(huì)極度下降。但找到這樣的算法的可能性是非常小的。今天只有短的RSA鑰匙才可能被強(qiáng)力方式解破。到2008年為止，世界上還沒有任何可靠的攻擊RSA算法的方式。只要其鑰匙的長(zhǎng)度足夠長(zhǎng)，用RSA加密的信息實(shí)際上是不能被解破的。 具體算法過程請(qǐng)參考http://zh.wikipedia.org/wiki/RSA%E5%8A%A0%E5%AF%86%E6%BC%94%E7%AE%97%E6%B3%95 代碼示例如下（來自MSDN）：www.elivn.com using System; using System.Security.Cryptography; using System.IO; using System.Text; namespace Microsoft.Samples.Security.PublicKey { class App { // Main entry point static void Main(string[] args) { // Instantiate 3 People for example. See the Person class below Person alice = new Person("Alice"); Person bob = new Person("Bob"); Person steve = new Person("Steve"); // Messages that will exchanged. See CipherMessage class below CipherMessage aliceMessage; CipherMessage bobMessage; CipherMessage steveMessage; // Example of encrypting/decrypting your own message Console.WriteLine("Encrypting/Decrypting Your Own Message"); Console.WriteLine("-----------------------------------------"); // Alice encrypts a message using her own public key aliceMessage = alice.EncryptMessage("Alice wrote this message"); // then using her private key can decrypt the message alice.DecryptMessage(aliceMessage); // Example of Exchanging Keys and Messages Console.WriteLine(); Console.WriteLine("Exchanging Keys and Messages"); Console.WriteLine("-----------------------------------------"); // Alice Sends a copy of her public key to Bob and Steve bob.GetPublicKey(alice); steve.GetPublicKey(alice); // Bob and Steve both encrypt messages to send to Alice bobMessage = bob.EncryptMessage("Hi Alice! - Bob."); steveMessage = steve.EncryptMessage("How are you? - Steve"); // Alice can decrypt and read both messages alice.DecryptMessage(bobMessage); alice.DecryptMessage(steveMessage); Console.WriteLine(); Console.WriteLine("Private Key required to read the messages"); Console.WriteLine("-----------------------------------------"); // Steve cannot read the message that Bob encrypted steve.DecryptMessage(bobMessage); // Not even Bob can use the Message he encrypted for Alice. // The RSA private key is required to decrypt the RS2 key used // in the decryption. bob.DecryptMessage(bobMessage); } // method Main } // class App class CipherMessage { public byte[] cipherBytes; // RC2 encrypted message text public byte[] rc2Key; // RSA encrypted rc2 key public byte[] rc2IV; // RC2 initialization vector } class Person { private RSACryptoServiceProvider rsa; private RC2CryptoServiceProvider rc2; private string name; // Maximum key size for the RC2 algorithm const int keySize = 128; // Person constructor public Person(string p_Name) { rsa = new RSACryptoServiceProvider(); rc2 = new RC2CryptoServiceProvider(); rc2.KeySize = keySize; name = p_Name; } // Used to send the rsa public key parameters public RSAParameters SendPublicKey() { RSAParameters result = new RSAParameters(); try { result = rsa.ExportParameters(false); } catch (CryptographicException e) { Console.WriteLine(e.Message); } return result; } // Used to import the rsa public key parameters public void GetPublicKey(Person receiver) { try { rsa.ImportParameters(receiver.SendPublicKey()); } catch (CryptographicException e) { Console.WriteLine(e.Message); } } public CipherMessage EncryptMessage(string text) { // Convert string to a byte array CipherMessage message = new CipherMessage(); byte[] plainBytes = Encoding.Unicode.GetBytes(text.ToCharArray()); // A new key and iv are generated for every message rc2.GenerateKey(); rc2.GenerateIV(); // The rc2 initialization doesnt need to be encrypted, but will // be used in conjunction with the key to decrypt the message. message.rc2IV = rc2.IV; try { // Encrypt the RC2 key using RSA encryption message.rc2Key = rsa.Encrypt(rc2.Key, false); } catch (CryptographicException e) { // The High Encryption Pack is required to run this sample // because we are using a 128-bit key. See the readme for // additional information. Console.WriteLine("Encryption Failed. Ensure that the" + " High Encryption Pack is installed."); Console.WriteLine("Error Message: " + e.Message); Environment.Exit(0); } // Encrypt the Text Message using RC2 (Symmetric algorithm) ICryptoTransform sse = rc2.CreateEncryptor(); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, sse, CryptoStreamMode.Write); try { cs.Write(plainBytes, 0, plainBytes.Length); cs.FlushFinalBlock(); message.cipherBytes = ms.ToArray(); } catch (Exception e) { Console.WriteLine(e.Message); } finally { ms.Close(); cs.Close(); } return message; } // method EncryptMessage public void DecryptMessage(CipherMessage message) { // Get the RC2 Key and Initialization Vector rc2.IV = message.rc2IV; try { // Try decrypting the rc2 key rc2.Key = rsa.Decrypt(message.rc2Key, false); } catch (CryptographicException e) { Console.WriteLine("Decryption Failed: " + e.Message); return; } ICryptoTransform ssd = rc2.CreateDecryptor(); // Put the encrypted message in a memorystream MemoryStream ms = new MemoryStream(message.cipherBytes); // the CryptoStream will read cipher text from the MemoryStream CryptoStream cs = new CryptoStream(ms, ssd, CryptoStreamMode.Read); byte[] initialText = new Byte[message.cipherBytes.Length]; try { // Decrypt the message and store in byte array cs.Read(initialText, 0, initialText.Length); } catch (Exception e) { Console.WriteLine(e.Message); } finally { ms.Close(); cs.Close(); } // Display the message received Console.WriteLine(name + " received the following message:"); Console.WriteLine(" " + Encoding.Unicode.GetString(initialText)); } // method DecryptMessage } // class Person } // namespace PublicKey |
