28 Jun 2013 pabs3   » (Master)

OpenPGP keysigning: alternate encodings for fingerprint exchange

I think that hexadecimal is a fairly poor pre-encoding for information exchange via data to speech and speech to data engines (aka voice boxes, brains and fingers). Reading out and typing long strings of hexadecimal digits at OpenPGP keysignings is tedious and annoying.

There have been some experiments using photography and QR codes for this, which I think is pretty cool but not always practical since not everyone has a camera and QR code software installed.

An alternative to this might be to pre-encode using a different scheme that encodes to less words in English speech. Diceware is one possibility that I recently experimented with. Diceware is a password generation scheme that encodes data from a random number generator (aka some dice) using a list of 7776 words. Each word thus represents a 5 digit number in base 6. Diceware is mainly used for generating strong and easier to remember passwords. So Diceware is the coupling between a non-digital random number generator and an interesting encoding scheme.

Below are my fingerprints in Diceware and Hexadecimal form. The Diceware form is longer to type at 69 characters, 40 for hex. The Diceware form has the advantage that it is only 16 words to say while the hexadecimal form is 40. I don't know if this will be more practical than hex but I can almost remember my entire fingerprint after reading it a few times so hopefully that will translate to practical use. A rough script for encoding your fingerprint in the Diceware encoding is available but I haven't implemented the reverse yet. I would be glad if someone could check it for correctness.

  Diceware:    frame maze bear usgs deter wag prissy bush hoyt mayo upton child indy
Hexadecimal: 610B 28B5 5CFC FE45 EA1B  563B 3116 BA5E 9FFA 69A3

If you want to discuss this topic and try it out in person and attempt to understand my accent, I'll be at DebConf13 and OHM2013. Some downsides that I can think of are accents, multiple spellings and the inclusion of non-words and special characters in the wordlist. These can be solved by using a different wordlist created specifically for OpenPGP fingerprint exchange that only includes suitable words.

This post was inspired by the screenshots for RedPhone. You can comment on this post on debian-project.

Syndicated 2013-06-28 05:42:59 from Advogato

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