随笔4

随笔4 2009-02-12 16:23 (分类:工作资料)

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2月12  加密算法；数据的序列化;元数据 反射；元数据
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加密算法

·对称加密
算法公开，计算量小，加密速度快，效率高，但是交易双方使用同样的密钥。安全性得不到保障。
此加密算法有：DES和IDEA
DES：8位校验码，56位数据信息
命名空间
 System.Security.Cryptography
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Security.Cryptography;

namespace Console3
{
    class Encryption
    {
        static void Main(string[] args)
        {
            string key="12345678";
            //>8
            string desIV="hello123456";
            //将字符串转换为流字节
            byte[] bKey=ASCIIEncoding.ASCII.GetBytes(key);
            byte[] bdesIV=ASCIIEncoding.ASCII.GetBytes(desIV);
            EncryptData("a.txt", "b.txt", bKey, bdesIV);
            DecryptData("b.txt", "c.txt", bKey, bdesIV);
        }
        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);//路径，方式，可读
            FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);//流对象为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);

            Console.WriteLine("Encrypting...");

            //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;
                Console.WriteLine("{0} bytes processed", rdlen);
            }

            encStream.Close();
            fout.Close();
            fin.Close();
        }
        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);//路径，方式，可读
            FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);//流对象为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);

            Console.WriteLine("Decrypting...");

            //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;
                Console.WriteLine("{0} bytes processed", rdlen);
            }

            encStream.Close();
            fout.Close();
            fin.Close();
           
        }
    }
}
C:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\Console1\Console1\bin\Debug
（明文+密钥+向量）Key+IV
string desIV="hello123456";
//string--->byte[]
 byte[] bdesIV=ASCIIEncoding.ASCII.GetBytes(desIV);
//string<---byte[]
String str = UnicodeEncoding.Unicode.GetString(bKey);
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MD5加密：存储Hash值
 public string MD5Encrypt(string strCipher)
        {
            byte[] data = ASCIIEncoding.ASCII.GetBytes(strCipher);
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] result = md5.ComputeHash(data);
            return UnicodeEncoding.Unicode.GetString(result);
        }
三重Md5加密
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·非对称加密
两个密钥：公开密钥和私有密钥
加密解密使用的是不同的密钥
DSA RSA
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** 数据的序列化**

将对象序列化为二进制或者SOAP格式
##
在异构网络中使用。SOAP：简单对象访问协议 是基于XMl（跨平台）的
在同构网络中可以使用二进制流，不需要跨平台
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通过 XmlSerializer 类、 IXmlSerializable接口及 XML 序列化属性和委托，将对象序列化为自定义 XML 格式

对象:
     DataTable dt = getDTa();
            BinaryFormatter BinForm = new BinaryFormatter();
            FileStream fs = File.Create("test.txt");
            BinForm.Serialize(fs, dt);
            fs = File.Open("test.txt", FileMode.Open);
            dt = (DataTable)BinForm.Deserialize(fs);
            fs.Close();
Xml:

     string filename = "c:\\Company.xml";

            XmlSerializer serializer = new XmlSerializer(typeof(Company));

            TextWriter writer = new StreamWriter(filename);

            Company com = new Company();
            com.CompanyName = "ABC InfoSystems";

            Employee emp1 = new Employee();
            Employee emp2 = new Employee();

            emp1.Name = "John";
            emp2.Name = "Peter";

            com.Employees = new Employee[2] { emp1, emp2 };

            serializer.Serialize(writer, com);

            writer.Close();

            FileStream fs = new FileStream(filename, FileMode.Open);

            Company cmp = (Company)serializer.Deserialize(fs);
            Console.WriteLine(cmp.CompanyName);
            foreach (Employee e in cmp.Employees)
            {
                Console.WriteLine(" {0}", e.Name);
            }
            Console.Write("\nPress ENTER to exit...");
            Console.ReadLine();

在一个类的前面加[Serializable]，说明该类可以被序列化和反序列化，并且该类不可以被继承
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Chapter 11 元数据
Assembly（程序集）包含若干个模块，模块包含若干类。
反射：在运行时检查程序集清单中的元数据的功能
为了更好的说明.Net反射的作用，先看两个殊途同归的例子：
//The conventional way to call an object.
BusinessObject bo=new BusinessObject();
bo.DoWork();

//The .Net reflection way to call an object.1、加载程序集 参数是namespace
Assembly assm=Assembly.Load("TestApp");
//2、获取类的类型
Type objType=assm.GetType("TestApp.BusinessObject");
//3、创建该类的实例
object objInstance=Activator.CreateInstance(objType);
//4、调用该实例中的方法
objType.InvokeMember("DoWork",BindingFlags.InvokeMethod,null,objInstance,null);

通过反射机制来调用一个方法，包括一下四步：
1、加载程序集
2、获取类的类型
3、创建该类的实例
4、调用该实例中的方法

应用：分布式网络编程中使用，系统的升级，只升级部分插件就可以
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多线程：
命名空间：System.Threading
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 public static void ThreadProc()
        {
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine("ThreadProc: {0}", i);
                // Yield the rest of the time slice.
                Thread.Sleep(0);
            }
        }

public static void Main()
        {
            Console.WriteLine("Main thread: Start a second thread.");
            // The constructor for the Thread class requires a ThreadStart
            // delegate that represents the method to be executed on the
            // thread.  C# simplifies the creation of this delegate.
            Thread t = new Thread(new ThreadStart(ThreadProc));

            // Start ThreadProc.  Note that on a uniprocessor, the new
            // thread does not get any processor time until the main thread
            // is preempted or yields.  Uncomment the Thread.Sleep that
            // follows t.Start() to see the difference.
            t.Start();
            Thread.Sleep(1000);

            for (int i = 0; i < 4; i++)
            {
                Console.WriteLine("Main thread: Do some work.");
                Thread.Sleep(0);
            }

            Console.WriteLine("Main thread: Call Join(), to wait until ThreadProc ends.");
            t.Join();
            Console.WriteLine("Main thread: ThreadProc.Join has returned.  Press Enter to end program.");
            Console.ReadLine();
        }

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SynchronizationContext类控制同步
委托的同步和异步操作