View source for Identity protocol v1



==Design goals==

Decentralized identity.

A SIN ("System Identification Number") is the unique record identifier by which this identity will be known.

Attributes:
* Has some creation cost
* Sacrifice may be digitally proven, bootstrapping root of trust from blockchain data
* Start as anonymous; opt out of anonymity by attaching identifying key-value pairs (real.name = "John Smith", gov.us.ssn = "123-45-6789").
* Forms the basis of distributed reputation systems
* Third parties may offer digital attestions:  Identity Verification, Inc. digitally signs a SIN as passing their Not A Criminal/Level-1 check.
* Controlled by the SIN's owner (key holder) at all times.

==Creating sacrifice transactions==

An implementation of [https://en.bitcoin.it/wiki/Fidelity_bonds#Announce.2FCommit_Sacrifices Announce/Commit Sacrifices].  That author's feedback on this protocol was very helpful.

# MPK = master public key
# TM = current block height
# Create and sign transaction T2. Broadcast if desired.
## must include Hash160(MPK) OP_TRUE anyone-can-spend output with value >= 0.001BTC
## nlocktime = TM + 144 blocks
## no more than 1000 bytes in size
# Create, sign and broadcast transaction T1
## must include OP_RETURN serialized(T2) output as last txout

==Creating a SIN==

# Prefix = 0x18
# SIN_Version = 0x01, similar to how [http://en.wikipedia.org/wiki/Universally_unique_identifier UUIDs]' form is dictated by a UUID's self-identified version
# MD = Hash160(MPK)
# SIN = base58_encode_check( Prefix + SIN_Version + MD )
# Hyphenate or space SIN for easier human reading

==Validating the root identity information==

# B1 = block w/ T1
# B2 = block w/ T2
# Verify B2 height - 144 >= B1 height.
# Verify announced T2 is valid
# Verify mined T2 spends same inputs as announced T2 (not equal to account for [[Transaction Malleability]])
# Fail and waste sacrifice if not.


Thus a minimal root record is MPK and is provably
* linked to the sacrifices
* MPK starts a new chain of digital signature trust, for further record updates

==Future work==

After that root identity is created, additional key-value pairs may be associated with the root record via updates verified by MPK, stored in an alt-blockchain or DHT somewhere.  That is outside the scope of this minimal document, at this time.