...by Daniel Szego
"Simplicity is the ultimate sophistication."
Leonardo da Vinci

Tuesday, August 28, 2018

How to implement a Blockchain from scratch - syncing accounts between state and wallet

In an account balance based blockchain system, there are accounts both in the blockchain state and in the wallet as well. It is important to understand the life cycle and syncronization between these elements:
- The accounts in the wallet should represent only a copy of the accounts of the state.
- Extended information can be stored art the accounts of the wallet, as an example the private keys for making signature simpler. 
- The accounts of the state should contain only public keys or addresses derived from public keys, not private key should be stored in the account of the chain. 
- After every new block, the wallet has to be synchronized. It is an open question how the synchronization should be carried out with the fork resolution strategy. There might be different strategies, like showing always the values of the top block of the actual state or waiting for a certain number of confirmations to avoid forks. 
- If a new transaction is initiated, it might refer to accounts that are still not in the state, only the public private keys or address were generated and they are only stored in the wallet. 
- At a currency transfer transaction the from account has to be in the state with a big enough fund and with a consistent nonce. 
- At a currency transfer transaction the to account should not necessarily be in the state. It can be added at the mining with the amount of money that is transferred to. It is important that the to account must be compatible with the from account if we consider a multi-asset scenario.
- There must be a couple of genesis accounts and or coinbase transactions for each cryptoasset, for the initial distribution of the monetary supply. The exact implementation depends on the issuance of the cryptoasset. For creating a genesis or coinbase of a new crptoasset, a new validation rule, perhaps a brand new transaction type has to be introduced.   
- At a data setting transaction, the initial account must not necessarily exist, it can be added anytime if there is a valid signature related to the address of the account.