[zapps-wg] My Powers of Tau Attestation

[Josh Cincinnati]

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Date: March 12th, 2018
Time: 6:00pm to 8:00pm PDT
Location: San Francisco, CA

For the compute node of my Powers of Tau contribution, I used a
refurbished late-2011 15" MacBook Pro, hardware which I've owned for
2.5 years, running Tails 3.5 off a USB stick.

I downloaded and compiled Filo Sottile's Golang implementation
(https://github.com/FiloSottile/powersoftau) using Go 1.10 in Ubuntu
17.10 on a separate desktop computer. I wiped another random USB stick
in my possession and copied the 'taucompute' executable and the
challenge file. Every time I copied the executable (on/off USB sticks,
onto computers, etc.) I checked the SHA256 hash, which stayed the same
throughout the process:

79c56ad4f1422ec134adac02857dc168a98e663041ca65e88ee903712eaf489d

This executable is available for inspection here:

https://drive.google.com/file/d/1Dl_avSDNR1A1lcWH8oEmWp-VNsGvNQkp/view?usp=sharing

I always wanted to use the coolest Faraday Cage I could find, so I set
up my compute node in the top shelf of my apartment's fridge. Prior to
initiating computation, I disconnected and powered down my apartment's
wireless access point and manually turned off every device within 10
feet of the fridge that had a radio. (note that I used my phone in
airplane mode to take pictures after Tails booted...but I turned it
off before computation began)

I added randomness in an undisclosed manner before beginning
computation. Computation began around 6:20pm PDT and finished at
7:10pm PDT--no doubt my cool Fridge-aday Cage sped things up a bit.
The fridge door was closed most of the time, but I periodically opened
it (every 15 minutes) to check on computation. I never left the fridge
out of my sight--and yes, there's definitely a "running fridge" joke
here somewhere.

Afterwards, I copied the response file onto another USB stick (along
with the 'taucompute' executable) and copied them both back onto my
desktop. The BLAKE2b hash of my response is:

822885fe 28daad52 2ff771fc 849eaa1c
c0cd5004 8249640e bf17560c e50cbc4a
13b7669d 6091b671 bec0c57e 3997b600
62198990 e74ef5c0 d739d3b3 ba58d3ab

I tweeted the BLAKE2b hash of my response file here as well:
https://twitter.com/acityinohio/status/973386393069105152

My PGP public key is available via Keybase:

https://keybase.io/cin/pgp_keys.asc

I plan on destroying the Macbook Pro in a manner that will be revealed
in a future blog post. Until then it remains powered off in my fridge
except when I transport it for destruction.

Thanks to Sean Bowe and everyone at the Zcash Company for building
this incredible MPC, Jason Davies for organizing, and all the other
participants in Powers of Tau! Glad I could contribute and make my
first full-time day at the Zcash Foundation memorable. :)
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