🚀 go-pugleaf

rteasdal@polyslo.csc.calpoly.edu (Rusty) writes:
>
>	A few months ago, in the letters section of the 
>_Communications of the ACM_, there was published a letter which
>commented that, in the opinion of the author, cryptographic	
>efficiency would be greatly enhanced by compressing a message
>before encrypting it, the better to remove repetitive patterns
>from the plaintext.
>
>	I don't see, though, that standard (i.e. LZW) compression
>algorithms actually do remove any of the redundancy from the text;
>they merely encode and substitute for lengthy repetitive patterns
>with smaller ones. Mathematically, the whole of the message is
>still there, is it not?
>

I'm no "crypto wizard", but what I know of cryptology and compression will
probably suffice.  (Correct me if I'm wrong!)...

In general, compressing your data before encrypting it will do *two* things
to increase security.  First, it makes the resulting message SMALLER.
Second, it makes the cleartext more RANDOM.  Both of these modifications
will make your communications more difficult to "crack".

SMALLER:  Less ciphertext means less hard data for the cracker to work with.
	Much of cryptanalysis is *statistical*, and the accuracy of statistical
	data increases with the amount of data to be analyzed.  Less data means
	more *guessing* for the cryptanalyst.

RANDOM:  Patterns in the plaintext can sometimes "show through" some algorithms
	into the ciphertext...  The more random the plaintext, the less chance
	there is of this happening.

	NOTE...  It is *STRONGLY* advised that the compression method used
		*NOT* add a standardized 'header' to its compressed output
		(like PKZIP does), as this will make the cryptanalysts' job
		*much* easier.

Rick Miller   <rick@ee.uwm.edu> | <rick@discus.mil.wi.us>   Ricxjo Muelisto
Occupation:  Husband, Father, WEPCo. WAN Mgr., Discus Sys0p, and  Linux fan