encryption bloats file

David Shaw dshaw at jabberwocky.com
Fri Jan 9 23:45:37 CET 2009

On Fri, Jan 09, 2009 at 03:33:05PM -0500, Scott Lambdin wrote:
> Hello -
> Someone sends us a big ~700MB pgp encrypted file and when we decrypt it the
> resulting file is about half that size.  Anyone have an idea what they might
> be doing to swell it up like that?

Most OpenPGP programs compress files before they are encrypted.  Some
files (for example, already compressed files) are poison to
compression and actually get bigger.  Doubling in size, however, is
not likely.  In any event, you don't say that program generated this
file, but at least GPG detects common forms of already-compressed data
and will not attempt to compress it further.

If you can send me such an encrypted file (my key is 99242560) I will
look at it and see what is going on.


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