Open HRMP channel between Khala and Karura

TL;DR

Similar with the earlier Kintsugi proposal , we propose to open HRMP communication between Khala and Karura.

Summary

We propose to open a bi-directional channel between Kurara and Phala. Initially, the main usecase will be to transfer PHA and KAR between the two chains, as a necessary step for the pre-proposal for list $PHA on Karura pools. What’s more, with Khala EVM bridge opened, user also can transfer KAR to the supported EVM chains directly.

Proposal

There is no on-chain proposal yet; #TBD.

Technical details:

The procedure for opening the channels is as follows:

  1. Karura propose to request to open Karura to Khala HRMP channel
  2. Wait until proposal on step 1 get approved & encated
  3. Khala propose to accept the request and request to open Khala to Karura HRMP channel(Batch call)
  4. Wait until proposal on step 3 get approved & encated
  5. Karura propose to accept Khala to Karura HRMP channel
  6. Wait until proposals on step 5 are approved & enacted
  7. Wait for another session on Kusama for the change to be effective
  8. XCM based crosschain transfer will be possible at this stage.

The extrinsics that need to be executed on the relay chain , are:

  • For step 1: hrmp.hrmpInitOpenChannel(recipient: 2004, proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400) , which hex-encoded is 0x3c00d4070000e803000000900100
  • For step 3: first call is hrmp.hrmpAcceptOpenChannel(sender: 2000), second call is hrmp.hrmpInitOpenChannel(recipient: 2000, proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400), the batch call hex-encoded is 0x1800083c01d00700003c00d0070000e803000000900100
  • For step 5: hrmp.hrmpAcceptOpenChannel(sender: 2004) , which hex-encoded is 0x3c01d4070000

The proposedMaxCapacity and proposedMaxMessageSize are set to the values of Kusama’s configuration.activeConfig.hrmpChannelMaxCapacity and configuration.activeConfig.hrmpChannelMaxMessageSize values, respectively.

These extrinsics need to be called with the parachain’s sovereign account as origin. To achieve this, on the Khala side we will use polkadot-xcm pallet to send xcm message to the relaychain, by executing the following extrinsic from the parachain. Karura should make a open request call and a accept request call with its orml-xcm pallet.

polkadotXcm.send(
  dest: XcmVersionedMultiLocation
  {
    V1: {
      parents: 1
      interior: Here
    }
  }
  
  message: XcmVersionedXcm
  {
    V2: [
      {
        WithdrawAsset: [
          {
            id: {
              Concrete: {
                parents: 0
                interior: Here
              }
            }
            fun: {
              Fungible: 100,000,000,000
            }
          }
        ]
      }
      {
        BuyExecution: {
          fees: {
            id: {
              Concrete: {
                parents: 0
                interior: Here
              }
            }
            fun: {
              Fungible: 100,000,000,000
            }
          }
          weightLimit: Unlimited
        }
      }
      {
        Transact: {
          originType: Native
          requireWeightAtMost: 1,000,000,000
          call: {
            encoded: 0x1800083c01d00700003c00d0070000e803000000900100
          }
        }
      }
      {
        RefundSurplus
      }
      {
        DepositAsset: {
          assets: {
            Wild: All
          }
          maxAssets: 1
          beneficiary: {
            parents: 0
            interior: {
              X1: {
                AccountId32: {
                  network: Any
                  id: 0x70617261d4070000000000000000000000000000000000000000000000000000
                }
              }
            }
          }
        }
      }
    ]
  }
)

As a prerequisite, the parachain’s sovereign account must contain at least 10 KSM to be locked as collateral (5 for each channel direction), plus some KSM to pay for xcm execution fees.

4 Likes

Great, finally moving on, that’s a long time waiting since your last post on this topic last September:)

yup, long time for almost every parachain

1 Like

Finnaalllyy !!! Let’s go my friends it’s time !! :heart_eyes:

1 Like