Chiral - Symmetric isomorphic binding: a committee-free, anchor-agnostic protocol where each chain verifies the other with a succinct on-chain light client

[janx]

Excellent work! Great to see the RGB++ idea expanding!

One question I have is that the definition of “leap” here seems to differ from RGB++’s use of the term:

• RGB++ leap refers to setting a CKB bound cell’s lock to a seal on any chain other than Bitcoin, e.g. setting the cell’s lock to a CKB or Litecoin seal. ‘Leap’ means transferring an RGB++ asset’s ownership from a Bitcoin seal to a non-Bitcoin one or vice versa. This transfer of ownership between seals on different chains allows RGB++ assets to effectively ‘move across chains without a bridge’.
• In Chiral, as described here, ‘leap-in’ looks more like RGB++ ‘mint’ - it creates a new bound cell on CKB and assigns its ownership to a Cardano seal. ‘Leap-out’ seems similar to RGB++’s ‘destroy/burn’. Does it mean that, in Chiral’s leap-in/transfer/leap-out, ownership never transfers to CKB but always remains on Cardano?

Refs

@T_Silva

• Leap-in (Cardano → CKB). Alice mints a unique seal NFT at the Plutus binding lock on Cardano, committing to a genesis state S0 (say, “1000 units, royalty = 2%”). A relayer presents that Cardano transaction, plus a Mithril proof that it is certified, to the CKB BoundAsset script, which mints the bound cell carrying S0 and naming Alice’s seal. The asset now lives as programmable state on CKB; ownership stays on Cardano.

@T_Silva

Leap-out (CKB → Cardano). Bob spends the seal on Cardano to a plain output without recreating it. The CKB bound cell is then finalized and burned, its script accepting a proof of the seal’s consumption-without-recreation.

RGB++ leap

Imagine such a situation: what if the unlocking condition of an eUTXO is set to another chain’s UTXO being spent, say, Litecoin’s UTXO? This would mean the ownership of the asset is tied to the Litecoin chain instead, and it should be considered a Litecoin chain asset. The asset magically leaps from the Bitcoin chain to the Litecoin chain — it is “bridged” across chains without a bridge!

Therefore, in the example mentioned above, if Alice wants to transfer her 40 TEST tokens (a Bitcoin Layer 1 asset) to the Litecoin chain, she first needs to spend the corresponding Bitcoin UTXO. Then, a transaction should be constructed on the RGB++ Layer to change the unlocking condition of the eUTXO (containing the asset definition) to her Litecoin UTXO. In this way, the leap from the Bitcoin chain to the Litecoin chain is successful because the ownership (UTXO as unlocking condition) is transferred across chains.

The Bitcoin chain and Litecoin chain in this example can be replaced with any two UTXO-based chains. Such cross-chain leaps are elegant and straightforward, something that only the UTXO model can achieve.

P.S. I couldn’t find any mention of “leap” in the RGB++ light paper or documentation, except for the Medium post. That might be one reason developers interested in RGB++ are getting confused.