Accounts

An account on the Concordium blockchain consists of two parts. The on-chain part which is publicly visible, and maintained by the bakers, and the off-chain part.

The on-chain part of the account consists of

  • the credentials associated with the account

  • public balance

  • shielded balance

  • account sequence number

  • public keys to verify transaction signatures.

The off-chain part of the account contains

  • private keys of the account which are used to sign actions by the account (e.g., sending transfers, deploying smart contracts)

  • the identity an account is created from (this is needed for managing the account on the chain)

  • decryption keys used for shielded transfers.

Concordium provides several ways of interacting with the on-chain account. Off-chain parts of accounts can be transferred between different devices, and the same account can be used from multiple devices at the same time.

Accounts on the chain are identified via an account address, which is a 32-byte sequence. The address is usually displayed in Base58Check encoding with version byte 1. An example of such an address is 3ZFGxLtnUUSJGW2WqjMh1DDjxyq5rnytCwkSqxFTpsWSFdQnNn.

In the tools described below the user will typically select an account name which makes the account easier to identify. This is only a local alias, and is not used by the Concordium blockchain. The name is resolved to an address before interactions with the node.

Account concepts

Account balances

Each account has two balances, the public balance which can be seen by every member of the Concordium Network, and a shielded balance, which is also referred to as encrypted balance. The shielded balance is only known to the owner of the account. It can only be used in shielded transfers to other accounts.

The public balance of the account is used for payment of transaction fees, baking, finalization, and transfers.

At any given time some of the public balance might be unavailable for use. This can happen in two ways:

  • the account has staked some (or all) of the public balance in order to become a baker

  • some of the public balance is locked up because it was received via a transfer with schedule

The locked-up balance can only be staked, but it can not be used for payment of transaction fees, nor can it be transferred to other accounts.

The relationship between the different balances can be best illustrated on an example.1 Suppose that on January 1 the account starts with 100 GTU on the public balance. None of it is locked-up or staked.

Then on January 2 the account receives 50 GTU via a transfer with schedule with the release scheduled for December 31 of the same year. At this point, January 2, the account has 100 GTU at disposal, the rest being locked. If the account tried to transfer more than 100 GTU the transaction would be rejected.

On January 3 the account becomes a baker with the initial stake of 125 GTU. This is successful because the total public balance is 150GTU. After this the account still has 25 GTU at disposal.

Account sequence number

Each account on the Concordium blockchain has a sequence number and each transaction signed by the account must have a sequence number. For a transaction to be considered valid its sequence number must be the next available one for the account. The sequence number is maintained by all the bakers in order to validate transactions.

The sequence number can be looked up from an up to date node by running

$concordium-client account show [ACCOUNT]

where [ACCOUNT] is an optional argument that is either an address of an account or the name of an account chosen when importing the account. If no address is provided, concordium-client will use the account name default.

The Concordium ID keeps track of the sequence number and assigns the correct one when sending transactions. concordium-client tracks the sequence number automatically, but it can also be set manually via the option --nonce.

Tools

The mobile wallet: Concordium ID

Concordium ID is a smartphone app that allows creation of accounts from identities issued by the external identity provider Notabene, as well as transfers of GTU from created accounts. It supports both plain and encrypted transfers.

This app can export identities and accounts that the user created.

Command-line tool

The Concordium distribution ships with a command-line tool named concordium-client. It is designed as a low-level interface to the Concordium blockchain. It cannot be used to create identities, but it can import accounts exported from the mobile wallets. Once an account has been imported, the tool can be used to do GTU transfers from the account, as well as send all other transaction types supported by the Concordium blockchain.

Support & Feedback

If you run into any issues or have suggestions, post your question or feedback on Discord, or contact us at testnet@concordium.com.

Footnotes

1

In this explanation we ignore transaction fees.