UK Friendly for e-commerce?

[Ian G Batten]

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> > Why can't I just use my DSS keys as El Gamal keys?
>=20
> I believe keys have to be more carefully chosen if they are to be
> suitable for use in one direction, as opposed to the other. But I do

There are, to judge from a quick glance at Schneier, more constraints on
a DSS key than an El Gamal key (in other words, you can do El Gamal with
a DSS key, but I'm not sure you can do the reverse).  Since the
constraint operates on `g', which is public anyway, I don't see there
to be an issue here.

> not know which is which, nor whether there is an easy test which can be
> done on a key to determine whether it is the "weak" or "strong" variety.

Yes, there is a test to see if a set of parameters is usable for DSS.
However, since the idea is to use DSS parameters to do El Gamal
encryption, this doesn't prove anything: shockingly, someone's DSS
public key will turn out to be usable for DSS...

ian

PS I've mailed Richard Clayton, but got your address wrong on the cc:,
to point out that the mutterings about your Content-MD5: lines are a bug
in dtmail, which I've wrestled with Sun over the years to fix.

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