Before bitcoin Alice and Bob needed a middleman to pay each other
With bitcoin they can pay each other directly
You can require multiple signatures too
But the world is full of trust problems that have needed courts or middlemen
Transactions are connected to reality
But bitcoin nodes don't know what reality is
The internet used to have the same problem with identity
We solved it with the Certificate Authority
The Certificate Authority for facts
The Certificate Authority for facts
The network looks after the money
The result is known, the winner unlocks funds
m of n
www.realitykeys.com
Trust (Ew)
Transparency
Redundancy helps - but watch out for correlated risk!
SchellingCoin and TruthCoin
SchellingCoin
https://blog.ethereum.org/2014/03/28/schellingcoin-a-minimal-trust-universal-data-feed/TruthCoin
https://github.com/psztorc/Truthcoin
People much cleverer than me working on this
They'll have to be - it's crazy hard
Leibniz and Svabo
Leibniz
Turn human language into formal grammar
Then let's calculate!
Turn human language into formal grammar
Then let's calculate!
Nick Svabo
Crypto-systems that manage assets can enforce contract logic
http://szabo.best.vwh.net/formalize.html
Crypto-systems that manage assets can enforce contract logic
http://szabo.best.vwh.net/formalize.html
Trusted parties could do more than just data
| Manage assets | Contract logic | External data | ||||
|---|---|---|---|---|---|---|
| Traditional trust-based systems | ||||||
| Bitcoin / Ripple | Codius | |||||
| Bitcoin / Ripple | Orisi | |||||
| Bitcoin / Ripple | Reality Keys | |||||
| Counterparty, Ethereum etc | Feed Providers | |||||
| TruthCoin | ||||||
Bit-thereum: http://gavintech.blogspot.jp/2014/06/bit-thereum.html
Using Reality Keys: The API
https://www.realitykeys.com/api/v1/runkeeper/400/?accept_terms_of_service=current
{"no_pubkey": "024e31a070c2c9dff13fbbeccc7ebe394caf3e82eae7092caf5602b55283c98bda", "user_profile": "edochan", "settlement_date": "2014-09-12", "objection_period_secs": 86400, "human_resolution_scheduled_datetime": null, "measurement": "cumulative_distance", "evaluation_method": "ge", "is_user_authenticated": true, "objection_fee_satoshis_paid": 0, "machine_resolution_scheduled_datetime": "2014-09-12 00:00:00", "user_id": "29908850", "goal": "1000", "created_datetime": "2014-09-05 23:14:02", "winner": "No", "value": "1000", "id": 400, "source": "runkeeper", "yes_pubkey": "02c4ec9347fa2cf7ab347a35f9816d4481e18811dfacfce9812b9896b0b4c34c89", "activity": "walking", "objection_fee_satoshis_due": 1000000, "user_name": "edochan", "winner_privkey": "L17zZNj1qfpSNMzRNK7FcfVeza6kwLUsmKA5uuLAChx6dxTnCgNw"}
Using Reality Keys: Multi-multi-sig
Traditional multi-sig
2 A-pub B-pub 2 OP_CHECKMULTISIG
Multi-sig branches
OP_IF
2 A-pub Yes-pub 2 OP_CHECKMULTISIG
OP_ELSE
2 B-pub No-pub 2 OP_CHECKMULTISIG
OP_ENDIF
Add a flag when you sign
0 A-sig Yes-sig 1 [p2sh-script]
0 B-sig No -sig 0 [p2sh-script]
Standard scripting with ECC math
ECC addition
| Private key | produces | Public key |
|---|---|---|
| x-priv | G(x) | x-pub |
| y-priv | G(y) | y-pub |
| x-priv + y-priv | G(x-priv+y-priv) | x-pub+y-pub |
Alice:
A-pub + Yes-pub = A-Yes-pub
Bob:
B-pub + No-pub = B-No-pub
1 A-Yes-pub B-No-pub 2 OP_CHECKMULTISIG
Alice wins:
A-priv + Yes-priv = A-Yes-priv
But be careful...
How stealth addresses work
Handy ECC fact
x-priv * Y-pub
==
y-priv * X-pub
Make a secret key that only participants know, eg
shared-secret-x-priv = Hash(x-priv * Y-pub)
Derive shared-secret-x-pub and pay it.
Whover knows x-priv can derive shared-secret-x-priv
For stealth addresses, this is the payee
https://wiki.unsystem.net/en/index.php/DarkWallet/Stealth
Same operations on Reality Keys keys make them private to participants.
(Other methods to make the shared secret work too.)
Multiple funders? You can fund atomically.
|
Create transaction:
2 BTC out But only 1 BTC in Sign transaction (If you don't know what coins the other party wants to spend, use SIGHASH_ANYONECANPAY) Publish / send / tweet transaction (Can't broadcast yet) |
|
|
Get transaction, recreate and check
Add funds 1 BTC + 1 BTC = 2 BTC Add signatures Broadcast transaction |
|
