Subject: Re: NIST publishes new DSA draft

From: <[email-masked]>
Date: Wed, 15 Mar 2006 14:14:02 -0500

On Tue, 14 Mar 2006 10:58:39 -0500 David Shaw 
<[email-masked]> wrote:
>In the OpenPGP context, probably the most interesting bit is that 
>the
>160-bit hash limit has been removed.  The sizes supported are:
>
>* 1024-bit key, 160-bit hash (the current DSA)
>* 2048-bit key, 224-bit hash (presumably aimed at SHA-224)
>* 2048-bit key, 256-bit hash (presumably aimed at SHA-256)
>* 3072-bit key, 256-bit hash (presumably aimed at SHA-256)
>
>It also adds the concept of using a larger hash than will fit by
>taking the leftmost bits.
>
>http://csrc.nist.gov/publications/drafts.html

the draft also refers to a previous draft of August/2005 (SP 800-
57)
which publishes a table of comparable strengths:
http://csrc.nist.gov/publications/nistpubs/800-57/SP800-57-
Part1.pdf
p.63

note that 3-DES is now referred to as TDEA
should this perhaps be included in rfc 2440 when 3-DES is 
mentioned?
i.e.
when 3-DES is first mentioned, 
it should be referred to as 3-DES(also known as TDEA)  

vedaal

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---

From: Jon Callas <[email-masked]>
Date: Sun, 19 Mar 2006 12:02:11 -0800

> it should be referred to as 3-DES(also known as TDEA)

They're not the same. There is DES and DEA, just as there is DSA and  
DSS. In each pair, there is an Algorithm and a Standard. The standard  
is the algorithm plus other stuff. In the case of DES, it specifies  
that the low bit of each byte (excuse me, octet) of the key is a  
parity bit (and possibly other stuff I don't remember). Everyone uses  
DES, not DEA. What we use is 3DES, not TDEA. In the case of DSS, we  
*do* mean DSA because there were people who wanted (for example) to  
use RIPE-MD/160 with DSA, not SHA-1, as DSS.

I suppose we could call it "TDES," but it's been called "3DES" or  
"Triple-DES" for ages. If all of a sudden we start calling it TDES,  
there will be many people who will rightly mutter, "TDES? What the % 
$@! is TDES? Oh, *3DES*, why didn't you say so?"

	Jon