Problems with DecryptFile Function
Printed From: Debenu Quick PDF Library - PDF SDK Community Forum
Category: For Users of the Library
Forum Name: I need help - I can help
Forum Description: Problems and solutions while programming with the Debenu Quick PDF Library and Debenu PDF Viewer SDK
URL: http://www.quickpdf.org/forum/forum_posts.asp?TID=1296
Printed Date: 05 May 24 at 7:41AM
Software Version: Web Wiz Forums 11.01 - http://www.webwizforums.com
Topic: Problems with DecryptFile Function
Posted By: Shotgun Tom
Subject: Problems with DecryptFile Function
Date Posted: 19 Dec 09 at 8:13PM
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I have spent the last two days trying to implement a decrypt file routine using, primarily, the QuickPDF DecryptFile function.
The function looks like it works in that it returns a success code and actually writes the file... but there is no PDF reader on the planet that will open the file. I thought for sure it must something I was doing. I tried securing several different files... some with just a user password some with user and owner passwords... different levels of encryption. I set the security in Adobe Pro 9.2.
Then I tried using Debenu's QuickPDF Tools. Lo and behold, the same thing. It writes the file but I can't open it in any PDF Reader... not Adobe, Acrobat, Fox-It, PCX View... they all give the same error. The file is corrupted. I assume that Debenu is using the DecryptFile routine in 7.17 which is what I've been dealing with.
Anyone else run into this problem? Is this a known issue?
Tom
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Replies:
Posted By: Michel_K17
Date Posted: 19 Dec 09 at 11:16PM
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Actually, I have been using this function (successfully) for the last 4 years. Here is my VB code. Note: make sure you use the "Owner" password. It will definitely not work with the "User" password. I hope it helps. '--------------------------------------------------------------------------------------- ' Procedure : PDF_Decrypt_File ' DateTime : 11/26/2005 10:41 ' Author : Michel_K17 ' Purpose : This function will take an encrypted/locked PDF, and save it unencrypted. '--------------------------------------------------------------------------------------- ' Private Function PDF_Decrypt_File(MyFile As String, pwd As String) As Boolean ' Trap Errors On Error GoTo Error_Handler ' Remove the Extension If Right$(MyFile, 4) = PDF Then MyFile = Left$(MyFile, Len(MyFile) - 4) ' Rename the file to process to an intermediate file Name MyFile & PDF As MyFile & "_D4W" & PDF ' Decrypt it rtn = oPDF.DecryptFile(MyFile & "_D4W" & PDF, MyFile & PDF, Decrypt(pwd, fUnicodeUser)) If rtn = 1 Then PDF_Decrypt_File = True ' Delete the intermediate file Kill MyFile & "_D4W" & PDF Exit Function Error_Handler: ' An unexpected error occured. Log it. (MUST have this line first, or the Err object gets reset). olog.LogError False, Err.Number, Err.Description, Err.LastDllError, "PDF_Decrypt_File" End Function ------------- Michel |
Posted By: Shotgun Tom
Date Posted: 20 Dec 09 at 2:03AM
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Hi Michel:
Thank you for your reply. I will try this code.
However, many, many files are encrypted only with a User Password. In other words, there are no permission's encryption, just a password for the User. If I can't use the User password, how can I decrypt those successfully?
Tom
BTW, I'm talking about permanently decrypting... that is... re-saving the file with no passwords, no security.
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Posted By: Ingo
Date Posted: 20 Dec 09 at 12:03PM
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Hi Tom! We're talking about main and user passwords. The user password is the one you have to insert while opening the pdf in a reader. The main password the user won't see ... it's only to make the pdf-settings a little bit saver. It's not possible to set only a user password. If the creator of a pdf determines a user- and not a main password the user password will be the main password, too. There's no problem to analyze the structure of a pdf if there are user- and/or main-passwords. If you want to decrypt AND SAVE a pdf which has a main- and a user-password it's okay to insert only the main-password. If there's a user-password you can't do things like previews and textextractions without the user password... and i think that's good ;-) This behavior doesn't belong only to the QuickPDF-sdk... that's normal for all libraries. Cheers, Ingo BTW: To all readers and writers here... Merry Christmas and a Happy New Year 2010! |
Posted By: Shotgun Tom
Date Posted: 20 Dec 09 at 2:52PM
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Hi Ingo (and Michel):
Thank you for the reply, Ingo. Just to let you guy's know... I finally went to bed and slept for a few hours. Woke up and found out what I was doing wrong. It had to do with having the document open in a viewer in the same program I was working on. Sometimes sleep helps your brain
 A very Merry Christmas and Happy New Year to you as well. Enjoy the holidays!
Tom
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