md4.cs

独立完成考勤管理软件加打卡系统（C＃） 是打卡加管理系统软件

using System;

namespace WindowsApplication
{
	/// <summary>
	/// MD4 的摘要说明。
	/// </summary>
	public class MD4
	{
		public MD4()
		{
			//
			// TODO: 在此处添加构造函数逻辑
			//
		}
		public static string EncryptString(string str)
		{
			char[] Base64Code=new char[]{'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5','6','7','8','9','+','/','='};
			byte empty=(byte)0;
			System.Collections.ArrayList byteMessage=new  System.Collections.ArrayList(System.Text.Encoding.Default.GetBytes(str));
			System.Text.StringBuilder outmessage;
			int messageLen=byteMessage.Count;
			int page=messageLen/3;
			int use=0;
			if((use=messageLen%3)>0)
			{
				for(int i=0;i<3-use;i++)
					byteMessage.Add(empty);
				page++;
			}
			outmessage=new System.Text.StringBuilder(page*4);
			for(int i=0;i<page;i++)
			{
				byte[] instr = new byte[3];
				instr[0]=(byte)byteMessage[i*3];
				instr[1]=(byte)byteMessage[i*3+1];
				instr[2]=(byte)byteMessage[i*3+2];
				int[] outstr=new int[4];
				outstr[0]=instr[0]>>2;
 
				outstr[1]=((instr[0]&0x03)<<4)^(instr[1]>>4);
				if(!instr[1].Equals(empty))
					outstr[2]=((instr[1]&0x0f)<<2)^(instr[2]>>6);
				else
					outstr[2]=64;
				if(!instr[2].Equals(empty))
					outstr[3]=(instr[2]&0x3f);
				else
					outstr[3]=64;
				outmessage.Append(Base64Code[outstr[0]]);
				outmessage.Append(Base64Code[outstr[1]]);
				outmessage.Append(Base64Code[outstr[2]]);
				outmessage.Append(Base64Code[outstr[3]]);
			}
			return outmessage.ToString();
		}
		/**************************************************字符串解密算法**************************************************/
		public static string DecryptString(string str)
		{
			if((str.Length%4)!=0)
			{
				throw new ArgumentException("不是正确的BASE64编码，请检查。","str");
			}
			if(!System.Text.RegularExpressions.Regex.IsMatch(str,"^[A-Z0-9/+=]*$",System.Text.RegularExpressions.RegexOptions.IgnoreCase))
			{
				throw new ArgumentException("包含不正确的BASE64编码，请检查。","str");
			}
			string Base64Code="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+/=";
			int page=str.Length/4;
			System.Collections.ArrayList outMessage=new System.Collections.ArrayList(page*3);
			char[] message=str.ToCharArray();
			for(int i=0;i<page;i++)
			{
				byte[] instr=new byte[4];
				instr[0]=(byte)Base64Code.IndexOf(message[i*4]);
				instr[1]=(byte)Base64Code.IndexOf(message[i*4+1]);
				instr[2]=(byte)Base64Code.IndexOf(message[i*4+2]);
				instr[3]=(byte)Base64Code.IndexOf(message[i*4+3]);
				byte[] outstr=new byte[3];
				outstr[0]=(byte)((instr[0]<<2)^((instr[1]&0x30)>>4));
				if(instr[2]!=64)
				{
					outstr[1]=(byte)((instr[1]<<4)^((instr[2]&0x3c)>>2));
				}
				else
				{
					outstr[2]=0;
				}
				if(instr[3]!=64)
				{
					outstr[2]=(byte)((instr[2]<<6)^instr[3]);
				}
				else
				{
					outstr[2]=0;
				}
				outMessage.Add(outstr[0]);
				if(outstr[1]!=0)
					outMessage.Add(outstr[1]);
				if(outstr[2]!=0)
					outMessage.Add(outstr[2]);
			}
			byte[] outbyte=(byte[])outMessage.ToArray(Type.GetType("System.Byte"));
			return System.Text.Encoding.Default.GetString(outbyte);
   
		}
	}
}