proof-of-hodl

proof-of-hodl is a command line tool to time-lock and release bitcoins using OP_CHECKSEQUENCEVERIFY - and - a web voting system where votes are weighted by amount of coins * lock duration.

NOTE: this is early hackathon-grade software, currently running on testnet.

Why lock?

Proving the sacrifice of some limited resource is a common technique in a variety of cryptographic protocols. In the case of locking coins, the option to trade and invest them is being temporarily sacrificed.

However, unlike similar forms of sacrifice such as sacrifice to miners fees or proof of burn, the time-lock sacrifice leaves the coins under one's control and thus implying confident and skin in the future value of bitcoin. This property makes HODL voting especially interesting for questions relevant to the future of bitcoin such as protocol changes.

CHECKSEQUENCEVERIFY

OP_CHECKSEQUENCEVERIFY is a new opcode in the bitcoin scripting language (activated July 2016) that allows to create time-locked outputs that cannot be spent until a pre-determined amount of time passes.

See BIP 112 and BIP 68 for more details.

CLI

The hodl lock command takes a lock-duration (in number of blocks), a refund address and a message (which the lock commits to), creates an address where funds to be locked can be deposited and once a payment was received, present the redeeming transaction so it can be saved and broadcast when the time arrives. It also provides a proof that can be shared and verified using the hodl verify command.

$ npm install -g hodl

$ hodl --help

$ hodl lock --duration [lock duration in blocks] --refund [addr] 'I support SegWit'

$ hodl verify [proof]

HODL.voting

HODL.voting is a web voting system based on proof-of-HODL sacrifices.

The code is at /web, and a live version is available at HODL.voting.

Votes over multiple choice questions are weighted by Bitcoin Days Locked (BDL) - the amount of coins multiplied by the number of days locked. The voter is prompted for an amount, lock duration and a refund address and presented with a QR code of a deposit address. Once a payment is received, a refund transaction is presented to be kept and broadcast later, as well as kept on the server for backup, and the vote is cast. Keys never leave the browser.

Technical

1. generate a random parentPrivkey, calculate parentPubkey = G*parentPrivkey
2. calculate seq = HMAC-SHA256(msg, parentPubkey)
3. derive childPrivkey = parentPrivkey+seq, childPubkey = G*childPrivkey
4. redeemScript = [childPubkey] OP_CHECKSIG [rlocktime] OP_CHECKSEQUENCEVERIFY OP_DROP
5. outputScript = RIPEMD160(SHA256(redeemScript))

License (ISC)

Copyright (c) 2017, Nadav Ivgi

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.