How to withdraw KSM tokens from Karura without using the Karura Bridge graphical interface?

Question

I transferred some KSM from the Kusama relay chain to the Karura parachain, and now I want to withdraw the tokens back to the relay chain.

That said, it seems that currently the Karura graphical interface is not working (down for meintenance) so I can't use the standard way of bridging the assets out of Karura back to Kusama.

How can I go about withdrawing the KSM tokens directly without having to use the Karura graphical interface?

Answer 1

You can withdraw the assets by submitting an XCM extrinsic directly to the Karura parachain (this applies to any parachain that uses the xtokens pallet: xtokens).

This can be done from the command line, but the easier way is to use the Polkadot.js interface for the relevant parachain, the Karura interface can be found here: Karura - Extrinsics.

An example of an xToken transfer in a JSON format looks like this:

[
  {
    name: "currency_id",
    type: "acala_primitives:currency:CurrencyId",
    type_name: "CurrencyId",
    value: {
      Token: "KSM"
    }
  },
  {
    name: "amount",
    type: "U128",
    type_name: "Balance",
    value: "123400000000"
  },
  {
    name: "dest",
    type: "xcm:VersionedMultiLocation",
    type_name: "Box<VersionedMultiLocation>",
    value: {
      V1: {
        interior: {
          X1: {
            AccountId32: {
              id: "0x46ebddef8cd9bb167dc30878d7113b7e168e6f0646beffd77d69d39bad76b47a",
              network: {
                Any: null
              }
            }
          }
        },
        parents: 1
      }
    }
  },
  {
    name: "dest_weight",
    type: "U64",
    type_name: "Weight",
    value: 5000000000
  }
]

Arg 1: currency_id defines the token you want to transfer - in our case it's KSM.

Arg 2: amount defines the amount of tokens you want to transfer - this value uses base units so 1 KSM is 1000000000000 in base units - in our case 123400000000 is equal to 0.1234 KSM

Arg 3: dest defines the destination address to which we want to send the tokens - note that this is the 32 byte account ID and not the SS58 address format (you can get the account ID from an address using the subkey inspect <SS58> command in the terminal).

Note: The parent junctions parameter parents should be set to 1 as we are sending the funds to an external address on the relay chain (i.e. 1 level up in the consensus hierarchy).

Arg 4: dest_weight defines the weight for XCM execution on the destination chain - here we set a constant of 5000000000.

Using the Polkadot.js interface we can fill out the xTokens.transfer() extrinsic information like so:

We can then submit the transaction and the KSM tokens should be transferred from Karura to Kusama when the transaction is included in the chain.