As in traditional blockchains, Linera wallets are in charge of holding user private keys. However, instead of signing transactions, Linera wallets are meant to sign blocks and propose them to extend the chains owned by their users.

In practice, wallets include a node which tracks a subset of Linera chains. We will see in the next section how a Linera wallet can run a GraphQL service to expose the state of its chains to web frontends.

The command-line tool linera is the main way for developers to interact with a Linera network and manage the user wallets present locally on the system.

Note that this command-line tool is intended mainly for development purposes. Our goal is that end users eventually manage their wallets in a browser extension.

Selecting a Wallet

The private state of a wallet is conventionally stored in a file wallet.json, while the state of its node is stored in a file linera.db.

To switch between wallets, you may use the --wallet and --storage options of the linera tool, e.g. as in linera --wallet wallet2.json --storage rocksdb:linera2.db.

You may also define the environment variables LINERA_STORAGE and LINERA_WALLET to the same effect. E.g. LINERA_STORAGE=$PWD/wallet2.json and LINERA_WALLET=$PWD/wallet2.json.

Finally, if LINERA_STORAGE_$I and LINERA_WALLET_$I are defined for some number I, you may call linera --with-wallet $I (or linera -w $I for short).

Chain Management

Listing Chains

To list the chains present in your wallet, you may use the command show:

linera wallet show
│ Chain ID                                                         ┆ Latest Block                                                                         │
│ 668774d6f49d0426f610ad0bfa22d2a06f5f5b7b5c045b84a26286ba6bce93b4 ┆ Public Key:         3812c2bf764e905a3b130a754e7709fe2fc725c0ee346cb15d6d261e4f30b8f1 │
│                                                                  ┆ Owner:              c9a538585667076981abfe99902bac9f4be93714854281b652d07bb6d444cb76 │
│                                                                  ┆ Block Hash:         -                                                                │
│                                                                  ┆ Timestamp:          2023-04-10 13:52:20.820840                                       │
│                                                                  ┆ Next Block Height:  0                                                                │
│ 91c7b394ef500cd000e365807b770d5b76a6e8c9c2f2af8e58c205e521b5f646 ┆ Public Key:         29c19718a26cb0d5c1d28102a2836442f53e3184f33b619ff653447280ccba1a │
│                                                                  ┆ Owner:              efe0f66451f2f15c33a409dfecdf76941cf1e215c5482d632c84a2573a1474e8 │
│                                                                  ┆ Block Hash:         51605cad3f6a210183ac99f7f6ef507d0870d0c3a3858058034cfc0e3e541c13 │
│                                                                  ┆ Timestamp:          2023-04-10 13:52:21.885221                                       │
│                                                                  ┆ Next Block Height:  1                                                                │

Each row represents a chain present in the wallet. On the left is the unique identifier on the chain, and on the right is metadata for that chain associated with the latest block.

Default Chain

Each wallet has a default chain that all commands apply to unless you specify another --chain on the command line.

The default chain is set initially, when the first chain is added to the wallet. You can check the default chain for your wallet by running:

linera wallet show

The Chain ID which is in green text instead of white text is your default chain.

To change the default chain for your wallet, user the set-default command:

linera wallet set-default <chain-id>

Opening a Chain

The Linera protocol defines semantics for how new chains are created, we call this "opening a chain". A chain cannot be opened in a vacuum, it needs to be created by an existing chain on the network.

Open a Chain for Your Own Wallet

To open a chain for your own wallet, you can use the open-chain command:

linera open-chain

This will create a new chain (using the wallet's default chain) and add it to the wallet. Use the wallet show command to see your existing chains.

Open a Chain for Another Wallet

Opening a chain for another wallet requires an extra two steps. Let's initialize a second wallet:

linera --wallet wallet2.json --storage rocksdb:linera2.db wallet init --genesis target/debug/genesis.json

First wallet2 must create an unassigned keypair. The public part of that keypair is then sent to the wallet who is the chain creator.

linera --wallet wallet2.json keygen
6443634d872afbbfcc3059ac87992c4029fa88e8feb0fff0723ac6c914088888 # this is the public key for the unassigned keypair

Next, using the public key, wallet can open a chain for wallet2.

linera open-chain --to-public-key 6443634d872afbbfcc3059ac87992c4029fa88e8feb0fff0723ac6c914088888

The first line is the message ID specifying the cross-chain message that creates the new chain. The second line is the new chain's ID.

Finally, to add the chain to wallet2 for the given unassigned key we use the assign command:

 linera --wallet wallet2.json assign --key 6443634d872afbbfcc3059ac87992c4029fa88e8feb0fff0723ac6c914088888 --message-id e476187f6ddfeb9d588c7b45d3df334d5501d6499b3f9ad5595cae86cce16a65010000000000000000000000

Opening a Chain with Multiple Users

The open-chain commands is a simplified version of open-multi-owner-chain, which gives you fine-grained control over the set and kinds of owners and rounds for the new chain, and the timeout settings for the rounds. E.g. this creates a chain with two owners and two multi-leader rounds.

linera open-multi-owner-chain \
    --chain-id e476187f6ddfeb9d588c7b45d3df334d5501d6499b3f9ad5595cae86cce16a65010000000000000000000000 \
    --owner-public-keys 6443634d872afbbfcc3059ac87992c4029fa88e8feb0fff0723ac6c914088888 \
                        ca909dcf60df014c166be17eb4a9f6e2f9383314a57510206a54cd841ade455e \
    --multi-leader-rounds 2

The change-ownership command offers the same options to add or remove owners and change round settings for an existing chain.

Setting up Extra Wallets Automatically with linera net up

For testing, rather than using linera open-chain and linera assign as above, it is often more convenient to pass the option --extra-wallets N to linera net up.

This option will create create N additional user wallets and output Bash commands to define the environment variables LINERA_{WALLET,STORAGE}_$I where I ranges over 0..=N (I=0 being the wallet for the initial chains).

Once all the environment variables are defined, you may switch between wallets using linera --with-wallet I or linera -w I for short.

Automation in Bash

To automate the process of setting the variables LINERA_WALLET* and LINERA_STORAGE* after creating a local test network in a shell, we provide a Bash helper function linera_spawn_and_read_wallet_variables.

To define the function linera_spawn_and_read_wallet_variables in your shell, run source /dev/stdin <<<"$(linera net helper 2>/dev/null)". You may also add the output of linera net helper to your ~/.bash_profile for future sessions.

Once the function is defined, call linera_spawn_and_read_wallet_variables linera net up instead of linera net up.