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SKS Protocol

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nicholas.cole at gmail

Aug 16, 2012, 12:42 PM

Post #1 of 5 (161 views)
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SKS Protocol

Is the SKS Synconization protocol documented anywhere? I've found the
links to the theoretical papers that underpin it, but no documentation
of the actual method used.

Apologies, of course, if I have missed something obvious....

Best wishes,

Nicholas

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John at enigmail

Aug 16, 2012, 5:34 PM

Post #2 of 5 (154 views)
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Re: SKS Protocol [In reply to]

Nicholas Cole wrote:
> Is the SKS Synconization protocol documented anywhere? I've found the
> links to the theoretical papers that underpin it, but no documentation
> of the actual method used.

Other than those two papers, every else is in the Ocaml code.
https://bitbucket.org/skskeyserver/sks-keyserver/wiki/Home

> Apologies, of course, if I have missed something obvious....

Is there something specific you're looking for?

Essentially, a hash is made of each key and stored in the PTree (Prefix tree)
database. This is the set used by the reconciliation algorithm described in
the papers.

You may find asking on the the SKS Development list to be more helpful.
mailto://sks-devel [at] nongnu

-John

--
John P. Clizbe Inet: John (a) Gingerbear DAWT net
SKS/Enigmail/PGP-EKP or: John ( @ ) Enigmail DAWT net
FSF Assoc #995 / FSFE Fellow #1797 hkp://keyserver.gingerbear.net or
mailto:pgp-public-keys [at] gingerbear?subject=HELP

Q:"Just how do the residents of Haiku, Hawai'i hold conversations?"
A:"An odd melody / island voices on the winds / surplus of vowels"

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nicholas.cole at gmail

Aug 16, 2012, 10:58 PM

Post #3 of 5 (155 views)
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Re: SKS Protocol [In reply to]

On Friday, August 17, 2012, John Clizbe wrote:

> Nicholas Cole wrote:
> > Is the SKS Synconization protocol documented anywhere? I've found the
> > links to the theoretical papers that underpin it, but no documentation
> > of the actual method used.
>
> Other than those two papers, every else is in the Ocaml code.
> https://bitbucket.org/skskeyserver/sks-keyserver/wiki/Home
>
> > Apologies, of course, if I have missed something obvious....
>
> Is there something specific you're looking for?
>
> Essentially, a hash is made of each key and stored in the PTree (Prefix
> tree)
> database. This is the set used by the reconciliation algorithm described in
> the papers.
>
> You may find asking on the the SKS Development list to be more helpful.
> mailto://sks-devel [at] nongnu <javascript:;>
>

Dear John,

Thank you. Yes, I feared I'd have to learn to read Ocaml! :-)

I was mostly interested in exactly how they made the hash of each key, but
it's also a really interesting and subtle problem they've fixed in getting
such reliable and rapid distribution of the database.

Best wishes,

Nicholas

John at enigmail

Aug 17, 2012, 4:56 PM

Post #4 of 5 (149 views)
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Re: SKS Protocol [In reply to]

Nicholas Cole wrote:
>
> Dear John,
>
> Thank you. Yes, I feared I'd have to learn to read Ocaml! :-)

Reading Ocaml is fairly easy. It's the thinking in a functional manner as
opposed to an imperative one that takes the effort.

The best place to start is the Ocaml Resources page. [0]
It has links to the language manual[1] and the standard library [2].
Version 4.00 of the Ocaml language was just released. We target version 3.11
and greater.

There are many more online. Email me off-list at the top address in my sig
block and I'll supply names and links. Do not bother with the book 'Practical
Ocaml' -- I received that advice too late, but I did not pay full price.

For the SKS source, I would suggest the trunk. There have been a LOT of
changes since 1.1.3. You may either clone it [3] or download a tarball[4] from
the 'get source' link on the project's Source tab (.zip, .gz, & .bz2 are
available).

> I was mostly interested in exactly how they made the hash of each key, but
> it's also a really interesting and subtle problem they've fixed in getting
> such reliable and rapid distribution of the database.

I need to go check before I answer, but I can tell you hashes are 128 bits.

-John

[0] http://caml.inria.fr/resources/index.en.html
[1] http://caml.inria.fr/pub/docs/manual-ocaml-4.00/index.html
[2] http://caml.inria.fr/pub/docs/manual-ocaml-4.00/libref/index.html
[3] hg clone https://bitbucket.org/skskeyserver/sks-keyserver
[4] https://bitbucket.org/skskeyserver/sks-keyserver/get/ac4a7159ca28.tar.bz2

--
John P. Clizbe Inet: John (a) Gingerbear DAWT net
SKS/Enigmail/PGP-EKP or: John ( @ ) Enigmail DAWT net
FSF Assoc #995 / FSFE Fellow #1797 hkp://keyserver.gingerbear.net or
mailto:pgp-public-keys [at] gingerbear?subject=HELP

Q:"Just how do the residents of Haiku, Hawai'i hold conversations?"
A:"An odd melody / island voices on the winds / surplus of vowels"

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John at enigmail

Aug 17, 2012, 5:51 PM

Post #5 of 5 (145 views)
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Re: SKS Protocol [In reply to]

John Clizbe wrote:
> Nicholas Cole wrote:
>
>> I was mostly interested in exactly how they made the hash of each key, but
>> it's also a really interesting and subtle problem they've fixed in getting
>> such reliable and rapid distribution of the database.
>
> I need to go check before I answer, but I can tell you hashes are 128 bits.

hashes are created calling the Ocaml standard library function Digest.string
which is built on MD5.

Exact details are in keyHash.ml [0]

-John

[0] https://bitbucket.org/skskeyserver/sks-keyserver/src/ac4a7159ca28/keyHash.ml

--
John P. Clizbe Inet: John (a) Gingerbear DAWT net
SKS/Enigmail/PGP-EKP or: John ( @ ) Enigmail DAWT net
FSF Assoc #995 / FSFE Fellow #1797 hkp://keyserver.gingerbear.net or
mailto:pgp-public-keys [at] gingerbear?subject=HELP

Q:"Just how do the residents of Haiku, Hawai'i hold conversations?"
A:"An odd melody / island voices on the winds / surplus of vowels"

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