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reducing size of encrypted file possible?

Posted: 08/06/2010 01:52:41
by Frank Munsberg (Standard support level)
Joined: 06/04/2009
Posts: 49

Hi there,

A colleague just told me that some batch that encrypted zip files had roundabout 40 - 50% increase in file size compared to the unencrypted zips.
The last thing we crypted was some 5gb zip file that must have resulted in some 7.5gb encrypted file.

Is there some sort of way to reduce the file size and still stay PGP compatible? We have to archive the encrypted files for 30 years or so and god knows what software will be around then to decrypt it. Would enabling compression be a valid way?

I'm using SBB 8.0.176 and TElPGPWriter.Encrypt(...) here to encrypt files with a public key. Upgrading to the latest version is possible of course.

The settings are basically

pgpWriter.Compress = false;
pgpWriter.EncryptionType = SBPGP.TSBPGPEncryptionType.etPublicKey;
pgpWriter.Filename = sourceFile.Name;
pgpWriter.InputIsText = false;
pgpWriter.Protection = SBPGPConstants.TSBPGPProtectionType.ptNormal;
pgpWriter.SignBufferingMethod = SBPGP.TSBPGPSignBufferingMethod.sbmRewind;
pgpWriter.SymmetricKeyAlgorithm = SBPGPConstants.Unit.SB_PGP_ALGORITHM_SK_AES256;
pgpWriter.UseNewFeatures = false;
pgpWriter.UseOldPackets = false;

Posted: 08/06/2010 01:58:40
by Eugene Mayevski (Team)

First of all, are you talking about ZIP or PGP? These are two unrelated technologies.

Sincerely yours
Eugene Mayevski
Posted: 08/06/2010 02:19:03
by Ken Ivanov (Team)

It is likely that armoring is turned on (armoring results in encrypted file size increase by 25%). Please ensure that the Armor property is off.



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