Re: [openpgp] Proposal to include AEAD OCB mode to 4880bis

Derek Atkins <> Mon, 30 October 2017 15:17 UTC

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From: Derek Atkins <>
To: Paul Wouters <>
Cc: Ronald Tse <>, "openpgp\" <>
References: <> <>
Date: Mon, 30 Oct 2017 11:16:15 -0400
In-Reply-To: <> (Paul Wouters's message of "Wed, 25 Oct 2017 12:27:30 -0400 (EDT)")
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Subject: Re: [openpgp] Proposal to include AEAD OCB mode to 4880bis
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Paul Wouters <> writes:

> On Wed, 25 Oct 2017, Ronald Tse wrote:
>> Since bis-02 now formally defines the AEAD packet and an AEAD
>> algorithm registry, I’d like to bring up the topic again of
>> adding OCB to the draft given its clear benefits. There have been
>> previous mentions of patent concerns, but OCB is freely
>> licensed for open source tools and has been included in libraries
>> like OpenSSL and Botan.
> What is the advantage of adding more and more algorithms and variants?

Different requirements in different use-cases.

> If OCB is clearly a winner over another algorithm candidate to be added,
> is the inferior other candidate removed?

Not necessarily.  Just because one is a "winner" does not necessarily
mean the other is "inferior".  Again, different use-cases have different
requirements that could result in different preferred choices.

> Adding algorithms is easy. Removing them is hard. That should raise the
> bar for adding new ones.

Historically the OpenPGP group has been relatively inviting and open to
addition (non-mandatory) algorithms.  I see no reason today that this
decades-old practice be changed.

> Paul

       Derek Atkins                 617-623-3745   
       Computer and Internet Security Consultant