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Durable Transaction Nonces

Durable transaction nonces are a mechanism for getting around the typical short lifetime of a transaction's recent_blockhash.

Usage Examples​

Full usage details for durable nonce CLI commands can be found in the CLI reference.

Nonce Authority​

Authority over a nonce account can optionally be assigned to another account. In doing so the new authority inherits full control over the nonce account from the previous authority, including the account creator. This feature enables the creation of more complex account ownership arrangements and derived account addresses not associated with a keypair. The --nonce-authority <AUTHORITY_KEYPAIR> argument is used to specify this account and is supported by the following commands

  • create-nonce-account
  • new-nonce
  • withdraw-from-nonce-account
  • authorize-nonce-account

Nonce Account Creation​

The durable transaction nonce feature uses an account to store the next nonce value. Durable nonce accounts must be rent-exempt, so need to carry the minimum balance to achieve this.

A nonce account is created by first generating a new keypair, then create the account on chain

Command

velas-keygen new -o nonce-keypair.json
velas create-nonce-account nonce-keypair.json 1

Output

2SymGjGV4ksPdpbaqWFiDoBz8okvtiik4KE9cnMQgRHrRLySSdZ6jrEcpPifW4xUpp4z66XM9d9wM48sA7peG2XL

To keep the keypair entirely offline, use the Paper Wallet keypair generation instructions instead.

Full usage documentation

Querying the Stored Nonce Value​

Creating a durable nonce transaction requires passing the stored nonce value as the value to the --blockhash argument upon signing and submission. Obtain the presently stored nonce value with

Command

velas nonce nonce-keypair.json

Output

8GRipryfxcsxN8mAGjy8zbFo9ezaUsh47TsPzmZbuytU

Advancing the Stored Nonce Value​

While not typically needed outside a more useful transaction, the stored nonce value can be advanced by

Command

velas new-nonce nonce-keypair.json

Output

44jYe1yPKrjuYDmoFTdgPjg8LFpYyh1PFKJqm5SC1PiSyAL8iw1bhadcAX1SL7KDmREEkmHpYvreKoNv6fZgfvUK

Full usage documentation

Display Nonce Account​

Inspect a nonce account in a more human friendly format with

Command

velas nonce-account nonce-keypair.json

Output

balance: 0.5 VLX
minimum balance required: 0.00136416 VLX
nonce: DZar6t2EaCFQTbUP4DHKwZ1wT8gCPW2aRfkVWhydkBvS

Full usage documentation

Withdraw Funds from a Nonce Account​

Withdraw funds from a nonce account with

Command

velas withdraw-from-nonce-account nonce-keypair.json ~/.config/velas/id.json 0.5

Output

3foNy1SBqwXSsfSfTdmYKDuhnVheRnKXpoPySiUDBVeDEs6iMVokgqm7AqfTjbk7QBE8mqomvMUMNQhtdMvFLide

Close a nonce account by withdrawing the full balance

Full usage documentation

Assign a New Authority to a Nonce Account​

Reassign the authority of a nonce account after creation with

Command

velas authorize-nonce-account nonce-keypair.json nonce-authority.json

Output

3F9cg4zN9wHxLGx4c3cUKmqpej4oa67QbALmChsJbfxTgTffRiL3iUehVhR9wQmWgPua66jPuAYeL1K2pYYjbNoT

Full usage documentation

Other Commands Supporting Durable Nonces​

To make use of durable nonces with other CLI subcommands, two arguments must be supported.

  • --nonce, specifies the account storing the nonce value
  • --nonce-authority, specifies an optional nonce authority

The following subcommands have received this treatment so far

Example Pay Using Durable Nonce​

Here we demonstrate Alice paying Bob 1 VLX using a durable nonce. The procedure is the same for all subcommands supporting durable nonces

Create accounts​

First we need some accounts for Alice, Alice's nonce and Bob

$ velas-keygen new -o alice.json
$ velas-keygen new -o nonce.json
$ velas-keygen new -o bob.json

Fund Alice's account​

Alice will need some funds to create a nonce account and send to Bob. Airdrop her some VLX

$ velas airdrop -k alice.json 1
1 VLX

Create Alice's nonce account​

Now Alice needs a nonce account. Create one

Here, no separate nonce authority is employed, so alice.json has full authority over the nonce account

$ velas create-nonce-account -k alice.json nonce.json 0.1
3KPZr96BTsL3hqera9up82KAU462Gz31xjqJ6eHUAjF935Yf8i1kmfEbo6SVbNaACKE5z6gySrNjVRvmS8DcPuwV

A failed first attempt to pay Bob​

Alice attempts to pay Bob, but takes too long to sign. The specified blockhash expires and the transaction fails

$ velas pay -k alice.json --blockhash expiredDTaxfagttWjQweib42b6ZHADSx94Tw8gHx3W7 bob.json 0.01
[2020-01-02T18:48:28.462911000Z ERROR velas_cli::cli] Io(Custom { kind: Other, error: "Transaction \"33gQQaoPc9jWePMvDAeyJpcnSPiGUAdtVg8zREWv4GiKjkcGNufgpcbFyRKRrA25NkgjZySEeKue5rawyeH5TzsV\" failed: None" })
Error: Io(Custom { kind: Other, error: "Transaction \"33gQQaoPc9jWePMvDAeyJpcnSPiGUAdtVg8zREWv4GiKjkcGNufgpcbFyRKRrA25NkgjZySEeKue5rawyeH5TzsV\" failed: None" })

Nonce to the rescue!​

Alice retries the transaction, this time specifying her nonce account and the blockhash stored there

Remember, alice.json is the nonce authority in this example

$ velas nonce-account nonce.json
balance: 0.1 VLX
minimum balance required: 0.00136416 VLX
nonce: F7vmkY3DTaxfagttWjQweib42b6ZHADSx94Tw8gHx3W7
$ velas pay -k alice.json --blockhash F7vmkY3DTaxfagttWjQweib42b6ZHADSx94Tw8gHx3W7 --nonce nonce.json bob.json 0.01
HR1368UKHVZyenmH7yVz5sBAijV6XAPeWbEiXEGVYQorRMcoijeNAbzZqEZiH8cDB8tk65ckqeegFjK8dHwNFgQ

Success!​

The transaction succeeds! Bob receives 0.01 VLX from Alice and Alice's stored nonce advances to a new value

$ velas balance -k bob.json
0.01 VLX
$ velas nonce-account nonce.json
balance: 0.1 VLX
minimum balance required: 0.00136416 VLX
nonce: 6bjroqDcZgTv6Vavhqf81oBHTv3aMnX19UTB51YhAZnN