[LeoPanthera]

"But, let’s say you have to do this without access to coins, computers, radioactive material, or other such access to traditional (pseudo) random number generators. All you have is a room of people."

Can you do a SHA1 in your head?

[guan]

Not quite in his head, but Ken Shirriff did SHA-256 with pencil and paper:

http://www.righto.com/2014/09/mining-bitcoin-with-pencil-and...