Accounts

Define a customer wallet state

The account contains complete information about a user's private wallet. It is linked by the intermediate key $\eta$ derived from the spending key $\sigma$owned by the user. The holder of the spending key is called an account owner.

The account holds the current balance value and spent offset which separates all notes into spent and unspent. This is sufficient data to retrieve a wallet state.

An account is a tuple $(d, P_d, i, b, e)$ where:

• $d$ (10 bytes) is a random diversifier which is updated every time an account is updated. It acts like a salt.

• $P_d$ (32 bytes) is diversified public key (a value derived from the $d$ and intermediate key $\eta$): $P_d = \eta * \text{ToSubGroupHash}_{E(F_r)}(d)$

• $i$(6 bytes) is the spent offset. It separates used (spent) and unused notes in the Merkle tree . Note that indexes below $i$ are considered to be spent.

• $b$(8 bytes) is the current account balance

• $e$(8 bytes) is an energy(XP) unit ("integral" account balance)

The raw account size is 64 bytes.

Account transaction data never appears unencrypted in a public field. Only the account owner can decrypt it.

Zero account

When a user creates their first transaction there will not be an existing account in the Merkle tree. In this case a zero account should be used where all fields are zero except $\eta$.​