How to make file password protect using c#

gunuti rajesh

How to make file password protect using c# , after download the image , while opening the image should ask password to open

4 Replies

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Rajkiran Swain9y ago
https://www.aspsnippets.com/Articles/Encrypt-and-Decrypt-Word-Excel-PDF-Text-or-Image-Files-using-C-and-VBNet-in-ASPNet.aspx
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Mukil Vendhan9y ago
hi friend kindly check this following link:https://youtu.be/dZJ_xWgdLqg
for encryption:
private const int SaltSize = 8;

public static void Encrypt( FileInfo targetFile, string password )
{
  var keyGenerator = new Rfc2898DeriveBytes( password, SaltSize );
  var rijndael = Rijndael.Create();

  // BlockSize, KeySize in bit --> divide by 8
  rijndael.IV = keyGenerator.GetBytes( rijndael.BlockSize / 8 );
  rijndael.Key = keyGenerator.GetBytes( rijndael.KeySize / 8 );

  using( var fileStream = targetFile.Create() )
  {
    // write random salt
    fileStream.Write( keyGenerator.Salt, 0, SaltSize );

    using( var cryptoStream = new CryptoStream( fileStream, rijndael.CreateEncryptor(), CryptoStreamMode.Write ) )
    {
      // write data
    }
  }
}
for decrypt:
public static void Decrypt( FileInfo sourceFile, string password )
{
  // read salt
  var fileStream = sourceFile.OpenRead();
  var salt = new byte[SaltSize];
  fileStream.Read( salt, 0, SaltSize );

  // initialize algorithm with salt
  var keyGenerator = new Rfc2898DeriveBytes( password, salt );
  var rijndael = Rijndael.Create();
  rijndael.IV = keyGenerator.GetBytes( rijndael.BlockSize / 8 );
  rijndael.Key = keyGenerator.GetBytes( rijndael.KeySize / 8 );

  // decrypt
  using( var cryptoStream = new CryptoStream( fileStream, rijndael.CreateDecryptor(), CryptoStreamMode.Read ) )
  {
    // read data
  }
}
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Manikandan Murugesan9y ago
Refer the following Link : https://www.codeproject.com/Articles/696528/Csharp-Password-Protected-File
You can not protect a text file with a password out of the box. You would need to encapsulate it, with an other application to do so.

The simplest way, would be to use a Zip File.

As taken form this post by Cheeso using DotNetZip:

using (var zip = new ZipFile()) { zip.Password= "VerySecret!!"; zip.AddFile("test.txt"); zip.Save("Archive.zip"); }

This results in 2 steps.

Create your files
Zip them and choose a password.
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Gokhul Varman9y ago
If you rhttps://stackoverflow.com/questions/19090282/protecting-a-file-by-a-passwordefer the link you can get a clear solution about it:
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