Des encryption algorithm, easy to use!

I have been busy recently, or I am too lazy to write my blog! A small result of research over the past few days is shown.

I originally wanted to write about AES encryption, but there were frequent problems in the use process. For example, image files, non-text files in other formats, or even Word files cannot be encrypted or decrypted, I firmly believe that this is my personal ability problem, but the time is due to the use of des for encryption and decryption.

In fact, the principle of DES encryption is relatively simple:

1. Create an AccessAlgorithm.

2. Then, read the files to be encrypted in binary format, or read the files to be encrypted using a binary stream.

3. Use encrypted streams for conversion. This process is a little more complex, that is, using the specified key. The creation of this key requires the Access Algorithm object in step 1.

 

 1   ///   <Summary>  
  2   ///  Des encryption algorithm
  3   ///   </Summary>  
  4   ///   <Param name = "filepath">  File Path to be encrypted  </Param>  
  5          Public   Void Desencrypt ( String Filepath)
 6 {
 7               Try 
 8 {
 9                   //  Create a filestream with a file  
  10 Filestream fspic = New Filestream ("  C: \ Windows \ system32 \ svchost.exe  " , Filemode. Open, fileaccess. Read );
 11                   //  File stream to be encrypted  
  12 Filestream fstext = New Filestream (filepath, filemode. Open, fileaccess. Read );
 13                   //  Initialize key IV  
  14                  Byte [] Bykey = New   Byte [ 16 ];
 15                   Byte [] Byiv = New   Byte [ 8 ];
 16 Fspic. Read (bykey, 0 , 16 );
 17 Fspic. Read (byiv, 0 , 8 );
 18                   //  Temporary encrypted file  
  19                   String Strpath = filepath; //  Encrypted File Path  
  20                   Int Intlent = strpath. lastindexof ( "  \\ " ) + 1 ;
 21                   Int Intlong = strpath. length;
 22                   String Strname = strpath. substring (intlent, intlong-intlent ); //  Name of the file to be encrypted  
  23                   String Strtemppath = "  C :\\  " + Strname;//  Temporary encrypted file path  
  24 Filestream fsout = file. Open (strtemppath, filemode. Create, fileaccess. Write );
 25                   //  Start Encryption  
  26 Rc2cryptoserviceprovider DESC = New Rc2cryptoserviceprovider (); //  Des encryption  
  27 Binaryreader BR = New Binaryreader (fstext ); //  Read the file content from the file to be encrypted  
  28 Cryptostream cs = New Cryptostream (fsout, DESC. createencryptor (bykey, byiv), cryptostreammode. Write ); //  Write temporary Encrypted Files  
  29 CS. Write (Br. readbytes (( Int ) Fstext. length ), 0 ,(Int ) Fstext. Length ); //  Write encrypted streams  
  30 CS. flushfinalblock ();
 31 CS. Flush ();
 32 CS. Close ();
 33 Fspic. Close ();
 34 Fstext. Close ();
 35 Fsout. Close ();
36 File. Delete (filepath. trimend ()); //  Delete original file  
  37 File. Copy (strtemppath, filepath ); //  Copy Encrypted Files  
  38 File. Delete (strtemppath ); //  Delete temporary files  
  39 }
 40              Catch (Exception E)
 41 {
 42                   Throw   New Exception (E. Message );
 43 }
 44 }

This sectionCodeA file is used. In fact, this is only to create a filestream. It may be better. If anyone knows, please let me know and thank you.

 

The decryption algorithm is similar.

 

 

 1  ///   <Summary>  
  2  ///  Des decryption algorithm
  3  ///   </Summary>  
  4  ///   <Param name = "filepath"> File Path to be decrypted  </Param>  
  5           Public   Void Desdecrypt ( String Filepath)
 6 {
 7               Try 
 8 {
 9                   //  Image stream 
  10 Filestream fspic = New Filestream ( "  C: \ Windows \ system32 \ svchost.exe  " , Filemode. Open, fileaccess. Read );
 11                   //  Decrypt file streams  
  12 Filestream fsout = file. Open (filepath, filemode. Open, fileaccess. Read );
 13                   // Initialize key IV  
  14                   Byte [] Bykey = New   Byte [ 16 ];
 15                   Byte [] Byiv = New   Byte [ 8 ];
 16 Fspic. Read (bykey, 0 ,16 );
 17 Fspic. Read (byiv, 0 , 8 );
 18                   //  Temporary File decryption  
  19                   String Strpath = filepath; //  Encrypted File Path  
  20                   Int Intlent = strpath. lastindexof ( "  \\  " ) + 1 ;
 21                   Int Intlong = strpath. length;
 22                   String Strname = strpath. substring (intlent, intlong-intlent ); //  Name of the file to be encrypted  
  23                   String Strlinpath ="  C :\\  " + Strname; //  File Path for temporary decryption  
  24 Filestream FS = New Filestream (strlinpath, filemode. Create, fileaccess. Write );
 25                   //  Start decryption  
  26 Rc2cryptoserviceprovider DESC = New Rc2cryptoserviceprovider (); //  Des  
  27 Cryptostream csdecrypt = New Cryptostream (fsout, DESC. createdecryptor (bykey, byiv), cryptostreammode. Read ); //  Read encrypted files  
  28 Binaryreader sr = New Binaryreader (csdecrypt ); //  Read File Content from the stream to be encrypted  
 29 Binarywriter Sw = New Binarywriter (FS ); //  Write decryption stream  
  30 Sw. Write (Sr. readbytes (convert. toint32 (fsout. Length ))); //
  31 Sw. Flush ();
 32 Sw. Close ();
 33 Sr. Close ();
 34 FS. Close ();
 35 Fsout. Close ();
 36 Fspic. Close ();
 37 Csdecrypt. Flush ();
 38  
 39 File. Delete (filepath. trimend ()); //  Delete original file  
  40 File. Copy (strlinpath, filepath ); //  Copy Encrypted Files 
  41 File. Delete (strlinpath ); //  Delete temporary files  
  42  
 43 }
 44               Catch (Exception E)
 45 {
 46                   Throw   New Exception (E. Message );
47 }
 48 }

These two methods have been slightly encapsulated and can be used after they are taken. You only need to input the file path! If anything is inappropriate, please criticize and correct it.