New vs Old (was Snake Oil)

Jill.Ramonsky at Aculab.com Jill.Ramonsky at Aculab.com
Tue Jun 3 08:58:14 EDT 2003


I confess to being confused - though admittedly part of the blame for this
is my own ignorance.

I remember a time when PGP was a command line application. The only
algorithms it used were IDEA (symmetric), RSA (assymetric) and MD5 (hash). I
came to trust these algorithms.

Now these once-'standard' algorithms are no longer encouraged. The new
versions of PGP seem to prefer CAST instead of IDEA, DH/DSS instead of RSA,
and SHA-1 instead of MD5.

So, could someone please tell me:

(1) What is the justification for using these "new" algorithms instead of
the old ones? (A cynic might suggest that, since the "powers that be"
couldn't break the old algorithms, they encouraged the use of new ones that
they could. This probably isn't true, but I'm sure you can understand why
someone might think that).

(2) What actually _IS_ DH/DSS? (I don't mean what do the initials it stand
for, I mean what actually is the algorithm?). I ask because I can understand
RSA, and implement it myself relatively straightforwardly, but I have not
been able to find an explanation, simple or otherwise, of what the DH/DSS
algorithm actually is, or of why it's hard to break.

(3) Ditto CAST and SHA-1.

Thanks

Jill



-----Original Message-----
From: Amir Herzberg [mailto:amir at herzberg.name]
Sent: Monday, June 02, 2003 5:25 PM
To: cryptography at metzdowd.com
Subject: Re: Maybe It's Snake Oil All the Way Down


Erik is right: there must be very strong motivation to consider using a 
cryptographic mechanism/protocol which is not `standard` (de-facto 
standards are Ok). 


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