1993-10-30 - Re: Paranoid

Header Data

From: Karl Lui Barrus <klbarrus@owlnet.rice.edu>
To: cypherpunks@toad.com
Message Hash: 6e582e03717379a08f9eef613d5d5d2e6452132f47a2c91250fd9303dc5670d6
Message ID: <9310301553.AA00702@elf.owlnet.rice.edu>
Reply To: N/A
UTC Datetime: 1993-10-30 15:53:27 UTC
Raw Date: Sat, 30 Oct 93 08:53:27 PDT

Raw message

From: Karl Lui Barrus <klbarrus@owlnet.rice.edu>
Date: Sat, 30 Oct 93 08:53:27 PDT
To: cypherpunks@toad.com
Subject: Re: Paranoid
Message-ID: <9310301553.AA00702@elf.owlnet.rice.edu>
MIME-Version: 1.0
Content-Type: text/plain


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I'm not exactly sure what this thread is about :-) but I do have some
numbers:

Differential cryptanalysis of DES requires 2^47 = 140737488355328 =
1.4 10^14 known plaintexts.

The complexity of a brute force DES attack (keysearch) is 2^56 =
72057594037927936 = 7.2 10^16, or 2^55 = 36028797018963968 = 3.6 10^16
if you are efficient.

Similary, brute forcing IDEA is 2^128 =
340282366920938463463374607431768211456 = 3.4 10^38

The best factoring algorithm (gopher plug: check in Misc/ for
a recent "bits and difficulty factoring post") for a 1024 bit key is 
a complexity of 4.42 10^29.

Somewhere around 1600 bits comes a point where it is "easier" to
attack IDEA than factor the resulting number.

Karl Barrus
<klbarrus@owlnet.rice.edu>

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