If a yield generator is run with a fidelity bond wallet then the
most-valuable bond will be found and announced.
The announcement includes a proof of a UTXO and its locktime. Also a
proof that the maker's IRC nickname controls the UTXO.
There is also an intermediate signature called the certificate
signature which can later be used when holding fidelity bond UTXOs in
cold storage without the protocol needing to change. Right now this
feature is unused so certificates are generated dynamically on each
request. The certificates have an expiry block height, which is defined
as the number of 2016-block retargeting periods since the genesis
block, so to check if the expiry was passed the taker will check
`current_block_height > cert_expiry*2016`.
chris-belcher
7a50c768da