Comments on: Compression and Encryption

By: Synetech

Synetech — Sun, 11 Nov 2012 00:56:26 +0000

I’m glad that you specifically used the words pattern and gibberish. RLE isn’t really used much these days for anything of import, so while it helps demonstrate the issue, it is a bit contrived. Using the terms “pattern” and “gibberish” makes it clear what is actually happening in a more generally applicable way: that compression hinges on finding patterns and that encryption destroys patterns.

By: kelanth

kelanth — Fri, 04 May 2012 11:25:09 +0000

Well, nicely said, but when trying to think a bit out of the box (which is often necessary), you can find out that this definitive answer of yours is not generally true. If you are still interested in this particular question, I recommend you to read an article from Klinc et. al. "On compression of data encrypted with block ciphers" (it is from 2009 btw.). If there is a will, there is a way;).

By: nhinkle

nhinkle — Tue, 22 Mar 2011 04:35:10 +0000

My above comment, now as a Super User question! "Do encrypted compression containers like zip and 7z encrypt or compress first?"

By: nhinkle

nhinkle — Tue, 22 Mar 2011 03:51:06 +0000

Nice post! Thanks for all the awesome info. Do you know then how encrypted ZIP files work? Encryption seems to be built into many encryption formats like zip, rar, 7z, etc. Do these usually compress and then encrypt, or somehow do both at once