[tor-dev] [RFC] Proposal for the encoding of prop224 onion addresses
Linda Naeun Lee
linda at torproject.org
Tue Jan 24 18:27:52 UTC 2017
On 2017-01-24 08:00, David Goulet wrote:
> On 24 Jan (14:27:43), George Kadianakis wrote:
>> s7r <s7r at sky-ip.org> writes:
>> > Hello George,
>> > George Kadianakis wrote:
>> >> Hello list,
>> >> we've had discussions over the past years about how to encode prop224 onion
>> >> addresses. Here is the latest thread: https://lists.torproject.org/pipermail/tor-dev/2016-December/011734.html
>> >> Bikeshedding is over; it's time to finally pick a scheme! My suggested scheme
>> >> <snip>
>> > The version field is useful and allows room for much stuff that we might
>> > need to do. I think it would be better to place it at the end of the
>> > address. I don't think all addresses should start with the same prefix
>> > tbh - this will make them slightly less distinguishable (as much as
>> > possible users should be able to differentiate onion addresses, which
>> > are re-usable for long term, as opposite to Bitcoin where the
>> > recommended way is to use 1 address 1 time, different one every time and
>> > the users just need to see a string that looks and reads like a Bitcoin
>> > address and just make sure it's copied (scanned) from/to the right place).
>> OK thanks for the useful discussion. I identified at least three
>> feedback points:
>> + Screw base58 it's not gonna work. We stick to base32. Usability will
>> be "restored" with a proper name system.
>> + Move version byte to the end of the address to avoid constant
>> prefix. Moving version byte to the middle as teor suggested would
>> cause forward-compatibility issues.
>> + My checksum calculations were wrong. Checksum is strong! 2 bytes are
>> And given the above, here is the new microproposal:
>> onion_address = base32(pubkey || checksum || version)
>> checksum = SHA3(".onion checksum" || pubkey || version)
>> pubkey is 32 bytes ed25519 pubkey
>> version is one byte (default value for prop224: '\x03')
>> checksum hash is truncated to two bytes
>> Here are a few example addresses (with broken checksum):
>> Checksum strength: The checksum has a false negative rate of
>> Address handling: Clients handling onion addresses first parse the
>> version field, then extract pubkey, then verify checksum.
>> Let me know how you feel about this one. If people like it I will
>> transcribe it to prop224.
> I like this quite a bit! Simple, easy, and trivial to understand. 56
> characters address, after that it will be the time to improve UX/UI
> with all
> sorts of possible tricks to make them easier to remember or copy paste
> visualize or what not.
> Unless some feedback NACK this, I say push that in the proposal soon.
> personally start implementing that scheme this week.
>> Thanks again Ivan, Ian, Linda, teor, s7r, Chelsea :)
>> tor-dev mailing list
>> tor-dev at lists.torproject.org
> tor-dev mailing list
> tor-dev at lists.torproject.org
+1; I like this proposal.
The hyphens help, but I don't think that is the only solution (though I
have no alternatives at the moment, except having short and
pronounceable names, which doesn't have the technical properties we
want) and we should be careful as it can introduce complexity/forward
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