Diffie Hellman V. ElGamal

David Shaw dshaw at jabberwocky.com
Fri Jun 18 20:48:22 CEST 2004

On Fri, Jun 18, 2004 at 01:53:25PM -0400, Hasnain Mujtaba wrote:
> Hi all,
> When we generate keys in GPG, we have the options of creating a ElGamal
> key pair. With PGP8, the option is DH/DSS. Why doesn't GPG provide a
> DH/DSS option? Isn't DH more common than ElGamal?

DH/DSS (PGP) == DSA and Elgamal (GnuPG).

For historical reasons, PGP calls Elgamal Diffie-Hellman, or DH.
Basically, when PGP 5 was being written, the patent holder on Diffie
Hellman told the company that if they called it DH instead of Elgamal,
they'd give them a free patent licence (there were still a few months
left in the patent).  Anyway, the patent has long since expired, but
the name stuck.


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