Open/Accept HRMP channel to/from Khala and Register PHA Asset

TL:DR

This batched proposal is to Accept/Open an HRMP channel with Khala and to register the PHA token

Summary

We propose to open a bi-directional channel between Moonriver and Khala. Initially, the main use case will be to transfer MOVR and PHA between the two chains, but it can be further expanded to other use cases. The proposal also includes the PHA asset registration as xcPHA, with the following details:

• Multilocation: { "parents": 1, "interior": {"X1": { "Parachain": 2004 }}}
• Decimals: 12
• Name: Phala Token
• Symbol: xcPHA

xcKHA will have the following asset ID and XC-20 address:
Asset ID: 189307976387032586987344677431204943363
XC-20 address: 0xffFfFFff8E6b63d9e447B6d4C45BDA8AF9dc9603

Proposal

Proposal #86 with the following hash: 0xe18dba49a8f101c64e51bf8a5a25dc65eb05af2449dda5a4fc5258f1de13965d

Technical details:

The procedure for opening the channels is as follows:

• Khala: already proposed to open an HRMP channel to Moonriver
• Moonriver: democracy batched proposal:
  • Open Moonriver to Khala HRMP channel
  • Accept Khala to Moonriver HRMP channel
  • Register PHA asset as an XC-20
• Khala: democracy proposal to accept Moonriver to Khala HRMP channel

Once the HRMP channels are ready, XCM based cross-chain transfer will be possible. The extrinsics that need to be executed on the relay chain, are:

• To open the HRMP channel from Moonriver: hrmp.hrmpInitOpenChannel(recipient: 2004, proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400), which its hex-encoded call data is 0x3c00d4070000e803000000900100
• To accept this HRMP channel: hrmp.hrmpAcceptOpenChannel(sender: 2023) , which hex-encoded call data is 0x3c01e7070000

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 from the parachain’s sovereign account as origin, via a democracy proposal. The proposal will use polkadotXcm pallet to send XCM message to the Relay Chain with the following items:

• Withdraw asset: take funds out of the Sovereign Account of the origin parachain (in the relay chain) to a holding state
• Buy execution: buys execution time from the relay chain, to execute the XCM message
• Transact: provides the call data to be executed
• Deposit asset (optional): refunds the leftover funds after the execution. If this is not provided, no refunds will be carried out

The asset will be registered with the metadata described in the summary. The setAssetUnitsPerSecond was calculated using the value for KSM, and the price ratio between KSM and KHA on April 17th, 2022.

If you are interested, the hex-encoded call data for this proposal in Moonriver is:

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

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.