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GNU Not able to Decrypt

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#1786
Posted: 12/05/2006 16:25:25
by Barry Dalton (Basic support level)
Joined: 12/05/2006
Posts: 5

Hi,

I have been using the PGP class to encrypt and decrypt files but I have a problem with a client not being able to decrypt files sent via a GNU PGP client. If I send them a file encrypted via the command line they are able to decrypt.

The error is as follows:

gpg: WARNING: potentially insecure symmetrically encrypted session key
gpg: CAST5 encrypted session key
gpg: gpg-agent is not available in this session
gpg: encrypted with 1 passphrase
gpg: encrypted with 2048-bit ELG-E key, ID F6FF9100, created 2006-12-05
"idms_zh (RBS Key) <contribution-ch@interactivedata.com>"
gpg: encrypted with ELG-E key, ID FEDD6941
gpg: encrypted with ELG-E key, ID DBFDF961
gpg: encrypted with RSA key, ID 6EB52DE3
gpg: decryption failed: unknown cipher algorithm

I have tested a decryption through PGP 8.5 and find no problems.

Are there known issues with GNU?

Thanks

Barry
#1788
Posted: 12/06/2006 01:30:43
by Eugene Mayevski (EldoS Corp.)

Well, the error message clearly states -- unknown cipher algorithm. Probably the algorithm you used to encrypt the data, is not supported by your version of GPG. You need to change the encryption algorithm.


Sincerely yours
Eugene Mayevski
#1790
Posted: 12/06/2006 02:33:43
by Barry Dalton (Basic support level)
Joined: 12/05/2006
Posts: 5

My apologies, I forgot to mention that we have tried CAST5 and Triple DES both of which are supported by GPG
#1791
Posted: 12/06/2006 02:51:03
by Ken Ivanov (EldoS Corp.)

Would you be so kind to encrypt some arbitrary file with SecureBlackbox sample keys (%SBB%\PGPKeys\secbbox.pkr) using your code and post it to the ticket so that we could try to reproduce the issue in our conditions?
#1792
Posted: 12/06/2006 04:37:46
by Barry Dalton (Basic support level)
Joined: 12/05/2006
Posts: 5

File attached


[ Download ]
#1793
Posted: 12/06/2006 06:15:57
by Ken Ivanov (EldoS Corp.)

GnuPG (1.4.2 for Win32) successfully decrypts the file you attached. So the problem might be caused by some particular GnuPG version.

Please also note, that the file is encrypted with 2 public keys and one password (!). Is this correct? I.e. do you really want to use both public key and password encryption?
#1794
Posted: 12/07/2006 04:51:15
by Barry Dalton (Basic support level)
Joined: 12/05/2006
Posts: 5

Well we found that a password was being set which would probably explain the double encryption but we are still having problems decrypting files encrypted with your software. This has been highlighted by 2 different clients using 2 different version of PGP.

We have implemented a temporary fix which takes black box out of the equation but this is not ideal. Do you know of any problems with the software that would cause this? Do you have any recommendations on the settings we use to encrypt files?
#1796
Posted: 12/07/2006 08:31:06
by Eugene Mayevski (EldoS Corp.)

Please ask the clients about the version of software they use.

You can also try setting

UseNewFeatures = false
UseOldFormat = true

This turns off new additions to OpenPGP format, not understood by some old software.


Sincerely yours
Eugene Mayevski
#1831
Posted: 12/12/2006 09:16:00
by Barry Dalton (Basic support level)
Joined: 12/05/2006
Posts: 5

We have clients using GPG v1.4.2 and PGP v6.5.1

We cannot find a setting called UseOldFormat but can find UseOldPackets....
#1832
Posted: 12/12/2006 09:28:02
by Eugene Mayevski (EldoS Corp.)

Yes, UseOldPackets.

"UseOldFormat" name is used in Generate method of the key classes.


Sincerely yours
Eugene Mayevski
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