Re: [HAM-AG] [IPv6] Request for feedback: draft-evan-amateur-radio-ipv6

How about the most significant bit be labeled the hash bit, when it is set
to 1 it allows for 59 bit hash of the callsign or set to 0 it allows for a
base-36 encoded callsign, with the last nibble being the node ID.

Kind of the best of both worlds.

Just a thought.

On Wed, Feb 15, 2023 at 18:34 Nick Harper <nharper@nharper.org> wrote:

> I had to look up that ITU regulation, so I don't know if there's a max
> length on temporary callsigns.
>
> If you treat the callsign as a base-36 number, you could squeeze up to 11
> characters into 60 bits.
>
> If you really want to handle callsigns of arbitrary length, you could use
> some of the 60-bit space for direct encodings of short (e.g. <=7
> characters) callsigns and the rest of the space for the hash of longer
> callsigns.
>
> On Wed, Feb 15, 2023 at 4:13 PM Evan Pratten <ewpratten@gmail.com> wrote:
>
>> I have personally held temporary callsigns longer than 7 characters,
>> which is why I wanted to handle that.
>>
>> Using a more space efficient encoding scheme is an interesting idea.
>> Do you know if there is a maximum length on temporary callsigns by
>> chance?
>>
>> I'll think about doing away with the hash in favor of space-efficient
>> encoding.
>>
>> On Wed, Feb 15, 2023 at 7:10 PM Nick Harper <nharper@nharper.org> wrote:
>> >
>> > Why hash the callsign at all?
>> >
>> > Article 19 of ITU's Radio Regulations specifies the format of
>> callsigns, and they are at most 7 characters long. The ASCII representation
>> of the callsign could be used to generate 7 bytes (56 bits) to use in the
>> address without needing any hashing. For the exception in 19.68A (on
>> special occasions, for temporary use, callsigns could be longer than 7
>> characters), a 6-bit encoding scheme could be devised so that alphanumeric
>> callsigns up to 10 characters long could be encoded in 60 bits.
>> >
>> > On Wed, Feb 15, 2023 at 3:28 PM Donald Eastlake <d3e3e3@gmail.com>
>> wrote:
>> >>
>> >> Hi,
>> >>
>> >> On Wed, Feb 15, 2023 at 3:03 PM Evan Pratten <ewpratten@gmail.com>
>> wrote:
>> >> >
>> >> > On Wed, Feb 15, 2023 at 2:58 PM Donald Eastlake <d3e3e3@gmail.com>
>> wrote:
>> >> > > I'm not sure the hash even needs to be cryptographic.
>> >> >
>> >> > Agreed. I would call a cryptographic hash *undesierable*. Why waste
>> >> > processing power hiding the callsign when you have to ID yourself
>> >> > anyways?
>> >> >
>> >> > I am admittedly far from an expert on hashing algorithms. Donald, do
>> >> > you have any suggestions that fit the properties you outlined by
>> >> > chance?
>> >>
>> >> Indeed, I would suggest using FNV-64 truncated to the top 60 bits, See
>> >> https://datatracker.ietf.org/doc/draft-eastlake-fnv/
>> >>
>> >> Here is an article on using FNV-32 for IPv6 flow label
>> >>
>> https://researchspace.auckland.ac.nz/bitstream/handle/2292/13240/flowhashRep.pdf
>> >>
>> >> Thanks,
>> >> Donald
>> >> =============================
>> >>  Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
>> >>  2386 Panoramic Circle, Apopka, FL 32703 USA
>> <https://www.google.com/maps/search/2386+Panoramic+Circle,+Apopka,+FL+32703+USA?entry=gmail&source=g>
>> >>  d3e3e3@gmail.com
>> >>
>> >> --
>> >> HAM-AG mailing list
>> >> HAM-AG@ietf.org
>> >> https://www.ietf.org/mailman/listinfo/ham-ag
>>
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