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Software components for data protection, secure storage and transfer

Error - Message was tampered

Also by EldoS: CallbackFilter
A component to monitor and control disk activity, track file and directory operations (create, read, write, rename etc.), alter file data, encrypt files, create virtual files.
#8348
Posted: 12/02/2008 12:35:10
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

Hello,
I am using SecureBlackbox.FTPS to make an ftp connection to download a pgp zipped folder, then using SecureBlackbox.PGP to decrypt the folder.

While working with small files, everything works as designed, it's when downloading a large transaction (500meg) that during the decryption process, the error message "Message was tampered" is triggered.

I attempted to decrypt the file with the sample project and also get the same message.

What may be causing this?

Thanks,
Alex
#8349
Posted: 12/02/2008 12:43:28
by Eugene Mayevski (EldoS Corp.)

What is "pgp zipped folder"? Did you first ZIP the folder, then signed/encrypted it with PGP?

What I can offer is double ZIPing. You ned to ZIP the encrypted file with zero compression (just store it). This will provide additional integrity checking. Then you will be able to test ZIP integrity prior to passing the PGP file to the PGP decryptor. This step will let us know whether the problem happens on FTP level or in PGP decryption procedure.



Sincerely yours
Eugene Mayevski
#8350
Posted: 12/02/2008 12:59:17
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

I'm sorry I didn't explain very clearly...

We have a customer that will be sending us a zipped folder that contains multiple files. I believe their intention is to pgp encrypt the zipped folder.

I'm trying to create my own test folder, assuming they will be doing as explained above, as we've yet to get a test transaction from them to be sure.

Thanks,
Alex
#8351
Posted: 12/02/2008 13:09:46
by Eugene Mayevski (EldoS Corp.)

thank you for the details. This corresponds to my ideas expressed in the above message. So if you are having problems with the large file, please follow the described procedure to find out, where the problem is. Then we will be able to help you further.


Sincerely yours
Eugene Mayevski
#8352
Posted: 12/02/2008 13:17:27
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

Thank you, I believe the issue is within my ftp download, as I by-passed this step by using a client to download the file, then the file decrypted as designed with the sample project.

I'll continue troubleshooting, focusing on the ftp download.

Thank you,
Alex
#8364
Posted: 12/03/2008 15:30:14
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

Hello, I am having a time with the proper way to encrypt and decrypt a folder containing multiple files. Could you please instruct me how to? I've tried just about everything, apparently all wrong, the latest is pgp encrypting at the folder level, but when I go to decrypt with the sample, I get the error "Invalid file name".

Thanks,
Alex
#8365
Posted: 12/03/2008 15:37:51
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

Sorry about that post, did not search... found my answer in another post...

"OpenPGP specification doesn't define a way to process multiple files.
PGP Desktop 9.x uses TAR format to gather all files into one file. Then this TAR file is processed (encyrpted or signed)."

From this statement, I am coming to the conclusion that I'm not going to be able to use OpenPGP to decrypt a folder containing multiple files that is submitted by our customer.

We do have PGP Desktop, which appears to be the solution we must go with.

Thanks,
Alex
#8366
Posted: 12/04/2008 01:07:27
by Eugene Mayevski (EldoS Corp.)

SecureBlackbox supports both archiving multiple files to a single PGP file and processing such PGP file with further extraction of all files contained in the embedded TAR. This feature is present in SecureBlackbox since one of 6.0 betas (namely build 132).

Check EncryptFiles() method of ElPGPWriter and OnMultipleFilesFound and OnFileExtractionStart events of TElPGPReader class.


Sincerely yours
Eugene Mayevski
#8435
Posted: 12/10/2008 07:30:08
by Alex Nail (Basic support level)
Joined: 08/27/2008
Posts: 16

Hello, I apologize for posting a new topic for this existing one created....as for the issue, yes, the sample projects produces the same issue.

Using the sample project to FTP download a 625meg file, then attempting to decrypt the transaction with the sample project produces the error of "Tampered".

Thank you,
Alex
#8436
Posted: 12/10/2008 08:10:15
by Ken Ivanov (EldoS Corp.)

Please check if the remote and downloaded files differ. It is necessary to detect on what stage does the problem actually occur (FTP download or PGP decryption).
Also by EldoS: MsgConnect
Cross-platform protocol-independent communication framework for building peer-to-peer and client-server applications and middleware components.

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