Re^3: Compressing and Encrypting files on Windows

Geez, tachyon, why don't you tell us what you really feel?

It's one thing to say, "sorry, I think you have that backwards, read my post to understand why;" and a completely different thing to use a caustic, abusive tone in every sentence. We've been without Abigail-II for months now, and I like the change in average tone in the community. Let's not blow it.

--
[ e d @ h a l l e y . c c ]

Comment on Re^3: Compressing and Encrypting files on Windows

Replies are listed 'Best First'.
Re^4: Compressing and Encrypting files on Windows by tachyon (Chancellor) on Nov 01, 2004 at 22:42 UTC
, why don't you tell us what you really feel? Because I thought it would get reaped ;-) The OPs post obviously annoyed me. I have no problem with people being wrong. Like most people I spout rubbish from time to time, but I typically have the good grace to add an AFAIK, IMHO, perhaps, maybe or whatever. It was the authoratative presentation of absolutely incorrect information that set me off. cheers tachyon	[reply]
Re^5: Compressing and Encrypting files on Windows by MidLifeXis (Monsignor) on Nov 02, 2004 at 18:18 UTC
Just a point - if you compress and then encrypt, you are encrypting known pieces of data (block headers, dictionaries, etc). Depending on the compression algorithm, this may give a large enough chunk of data to assist an attack against the encrypted data stream. All of this is IIRC, of course ;) --MidLifeXis	[reply]
Re^6: Compressing and Encrypting files on Windows by tachyon (Chancellor) on Nov 02, 2004 at 23:21 UTC
As you say knowing that the first two bytes of a valid decrypt must be say the gzip header bytes 0x1f 0x8b does provide a small chink that can potentially be exploited. If you are that paranoid they are easy to hide. Making two passes with the encryption algorithm is one easy way. cheers tachyon	[reply]