From: karn@qualcomm.com (Phil Karn)
Date: Wed, 23 Jun 93 18:19:11 PDT
To: cypherpunks@toad.com
Subject: Re: Weak steganography
Message-ID: <9306240119.AA00555@servo>
MIME-Version: 1.0
Content-Type: text/plain


At 10:45 AM 6/17/93 -0700, Hal Finney wrote:

>Another problem is that encrypted files look different from executable
>files.  Encrypted files have a uniform histogram (that is, all 256 different
>possible byte values are equally frequent), but exe files do not.

Not necessarily. If you use pklite or lzexe, you produce an automatically
self-decompressing executable that will appear to have a much flatter
distribution than an ordinary exe file.

What we need is a crypto version of pklite - instead of (or in addition to)
compressing the executable, it encrypts it and sticks a stub decryptor
on the front of the executable. Each time you run it, it prompts you for
a password, decrypts and decompresses the executable and runs it.

Phil