how to decrypt pdf by using a key RSS

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  dileepkumark...

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  how to decrypt pdf by using a key

  Apr 06, 2012 10:06 AM|LINK

  Hello,

  I have a different requirement, pdf is encrypted by using a key and that encrypted pdf will be sent to client, when anybody opens

  that pdf, it asks for key, if right key applied pdf should be decrypted and displayed.

  I have used RijndaelManaged Algorithm for encrypting pdf file, pdf is getting encrypted, but when i double click on that

  encrypted pdf its not asking for key. It should ask for key and pdf will be decrypted and will be opened.

  I have two programs , one for encryption , one for decryption. I am successfully encrypting and decrypting by using those

  prg's. but for decrypting i cannot use program, when we double click on file then only decryption program runs and check

  for right key, should be decrypted. 

  I have been really searching for this specific thing for the past 48 hours. I did not find any solution. 

  Please help me out from this problem...

  This is my code to encrypt pdf by using a key

  UnicodeEncoding UE = new UnicodeEncoding();
  byte[] key = UE.GetBytes(password);

  string cryptFile = outputFile;

  FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

  RijndaelManaged RMCrypto = new RijndaelManaged();

  CryptoStream cs = new CryptoStream(fsCrypt,
  RMCrypto.CreateEncryptor(key, key),
  CryptoStreamMode.Write);

  FileStream fsIn = new FileStream(inputFile, FileMode.Open);

  int data;
  while ((data = fsIn.ReadByte()) != -1)
  cs.WriteByte((byte)data);

  
  fsIn.Close();
  cs.Close();
  fsCrypt.Close();

  This is my decryption program.

  UnicodeEncoding UE = new UnicodeEncoding();
  byte[] key = UE.GetBytes(password);

  FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

  RijndaelManaged RMCrypto = new RijndaelManaged();

  CryptoStream cs = new CryptoStream(fsCrypt,
  RMCrypto.CreateDecryptor(key, key),
  CryptoStreamMode.Read);

  FileStream fsOut = new FileStream(outputFile, FileMode.Create);

  int data;
  while ((data = cs.ReadByte()) != -1)
  fsOut.WriteByte((byte)data);

  fsOut.Close();
  cs.Close();
  fsCrypt.Close();

  Thanks in Advance...

  • Moved by XIII on Apr 12, 2012 07:34 AM
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  dileepkumark...

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  7 Posts

  Re: how to decrypt pdf by using a key

  Apr 10, 2012 06:35 AM|LINK

  hi dev-guru,

  Thanx for advise. 

  your above lines of code will only do password protection for pdf, but it will not encrypt text in pdf.

  I want something which encrypts data in pdf file using a password or key, and any body can view that pdf provided same key.

  any advises are greatly welcome

  Dileep kumar.

• • Reply
  

  dileepkumark...

  0 Points

  7 Posts

  Re: how to decrypt pdf by using a key

  Apr 13, 2012 05:14 AM|LINK

  Hi,

  I have earlier used ITextSharp.dll , but i didnot get the solution. I finally findout solution in someother way.

  string outputFile = @"E:\javascript6secure.pdf";
  string inputFile = @"E:\javascript6.pdf";

  using (Stream input = new FileStream(inputFile, FileMode.Open, FileAccess.Read, FileShare.Read))
  {
  using (Stream output = new FileStream(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
  {
  PdfReader reader = new PdfReader(input);
  PdfEncryptor.Encrypt(reader, output, true, "secret", "secret", PdfWriter.ENCRYPTION_AES_128);

  }
  }

  As you said ITextSharp.DLL is used here. Pdf is converted and even search engines cannot access these pdf's meta data.

  • Marked as answer by Young Yang - MSFT on Apr 30, 2012 02:25 PM