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Handling address expiry and uniqueness

How To

Gateway address uniqueness​

The gateway address of a LockAndMint is deterministic based on its constructor parameters. This means that if a user is minting the same asset to the same recipient multiple times, they will be shown the same address.

If this is not the desired behaviour, a nonce can be provided to the lockAndMint function along side the other parameters to ensure that a new address is generated.

The nonce should be a 32-byte Buffer, which can be created using the bn.js library:

const lockAndMint = await renJS.lockAndMint({
    ...
    // To set the nonce to 42.
    nonce: new BN(42).toArrayLike(Buffer, "be", 32),
})

It is best if the nonce is incremental for the user, using persistent storage to track it. If a random nonce is used, it should still be stored to persistent storage to that the LockAndMint can be resumed if the user's session is closed.

caution

Just like all the other parameters, the LockAndMint can only be resumed by providing the nonce again. If the nonce is lost, the funds may not be recoverable.

Gateway address expiry​

Currently, gateway addresses do not expire. An upcoming update to RenVM will change this.

The network will have 24-hour cycles, and the gateway address timeline will look like this:

  • 1st time cycle:
    • If a user wants to make a deposit, an address for this cycle is generated. They have the rest of this time cycle to initiate the deposit.
  • 2nd time cycle:
    • If the user sent a deposit, the deposit needs to be confirmed and submitted to RenVM before the end of the cycle.
    • If the user wants to make a new deposit, a new address is generated for this new time cycle, starting a new three-cycle timeline.
  • 3rd time cycle:
    • The user has the rest of the time cycle to submit the RenVM signature to the mint-chain.
    • Like before, if the user wants to make a new deposit, a new address is generated for this new time cycle.

Each of the steps can happen sooner if the deposit is ready - the deposit, signing and submitting to the mint-chain can all happen in the same cycle.

In expectation of this, Bridge (bridge.renproject.io) is using the nonce described above to replicate this behaviour. The nonce is calculated based on the current time cycle and the number addresses the user has already generated for that cycle.