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Quick Overview

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Universal transaction ledger

Protocol determines:

order

meaningin terms of state change

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Arbitrary state stored between transactions

Arbitrary state changes due to transactions

thus

Provides arbitration & enforcement for agreements with arbitrary mechanics

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Transaction state-transition function

σ' = (σ, T, H)ϒ

Block reward function

σ' = Ω(σ, B)

Block state transition funtion

σ' = Π(σ, B)

where

B = (H, (T[0], T[1], …), U)

Π(σ, B) = Ω( ( (σ, T[0], H), T[1], H), B)ϒ ϒ

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What?

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Address: public key (-ish)

System stores an account per address:

value

transaction count

state

code

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Accounts

Create with codeNo private key (arbitrary public deterministically) chosen;

Thus no external access.

Create through sending fundsPossibility of private key (public assumed to be derived);

Full external access; no code possible.

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Transaction state-transition (σ, T, H)ϒ

Resultant state depends on T type;

Creation or Message

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Creation used to create account with associated code.

Message transfers value & invokes associated code.

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Code execution:

Turing-complete instruction set machine;

stack-based architecture, with memory.

Code in separate ROM; and...

arbitrary-sized storage.

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No I/O, but...

Instructions to make messages or create

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Message Invokation

Runs code in fresh instance of machine

Runs with contract's existing state

Passed byte-array input & can return output.

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Creation

Creates a new contract

Runs initialisation code which returns the machine's code ROM

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VM Execution fully deterministic

Only I/O is invokation & creation

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How?

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Peer-network that shares:

Blocks

Transactions

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Transactions:

Cryptographically signed

Either create (includes init code);or message (includes destination & input data)

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Blocks:

Includes parent block's hash

Series of transactions

Includes cryptographic proof-of-work

Author takes a reward

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Block-tree forms from blocks

“GHOST” protocol:

Reduced to block-chain as the root-leaf that required greatest computation (sum of

proof-of-work, including immediate relatives)

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Consensus state is the final state of the canonical block chain

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Why?

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Decentralised zero-trust or distributed-trust systems.

In short

Crypto-Law.

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Useful abstraction platform for:

Virtual currencies (Bitcoin)

Digital proxy currencies (CFD, 'Goldcoin')

Financial instruments (Cons. Tape, Mastercoin)

Registrars (ICANN, Namecoin)

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Reputation systems (Facebook, eBay)

Voting systems

DAOs

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Limitations

Scalability all nodes evaluate all transactions, store all state

Public impossible to work with secrets

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Future

Add:

decentralised publication & distribution,

diffuse, secure messaging:

Post-Snowden Web;Web 3.0