最近收到了很多朋友的來信說希望提供DES的C#代碼，但是我個人認為，.NET 提供了很多標準函數(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，也可以自己動手實現(xiàn)整個過程，這個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?shù)那宄?.NET 提供了很多標準加密、解密函數(shù)，我簡要介紹一下DES，SHA1，RSA的標準函數(shù)的使用。如果你想做一個網(wǎng)絡安全模塊，只需將三種算法結合起來設計一個模型，我相信可以實現(xiàn)很多復雜的功能。 示例本身并不復雜，我也不做過多解釋，我也學Linus Torvalds一樣吼一句："Read the f**ing code”，哈哈，開個玩笑，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清楚了，加上我博客里關于DES的文章確實不少，所以DES不做任何解釋，怎么調用就更不用解釋了吧，呵呵： ????????//默認密鑰向量
????????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)字簽名標準（Digital Signature Standard DSS）里面定義的數(shù)字簽名算法（Digital Signature Algorithm DSA）。對于長度小于2^64位的消息，SHA1會產生一個160位的消息摘要。當接收到消息的時候，這個消息摘要可以用來驗證數(shù)據(jù)的完整性。在傳輸?shù)倪^程中，數(shù)據(jù)很可能會發(fā)生變化，那么這時候就會產生不同的消息摘要。

SHA1有如下特性：不可以從消息摘要中復原信息；兩個不同的消息不會產生同樣的消息摘要。

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稱加密算法。在公鑰加密標準和電子商業(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。當時他們三人都在麻省理工學院工作。RSA就是他們三人姓氏開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。只要其鑰匙的長度足夠長，用RSA加密的信息實際上是不能被解破的。 具體算法過程請參考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

轉載于:https://www.cnblogs.com/seoxs/archive/2011/04/21/2023149.html

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