Cosmos integration.

[artemii235]

Full Cosmos/Tendermint support in AtomicDEX.
Useful resources:

• Cosmos SDK documentation https://docs.cosmos.network/
• Tendermint RPC spec https://docs.tendermint.com/master/spec/rpc/
• Public RPC nodes and testnet faucet https://www.allthatnode.com/cosmos.dsrv
• Rust SDK https://github.com/cosmos/cosmos-rust
• Block explorer of Cosmos ecosystem https://www.mintscan.io
• Atom testnet block explorer https://explorer.theta-testnet.polypore.xyz/

[artemii235]

I've made a brief research on atomic swaps support on Cosmos, discovered the following:

1. Main Cosmos Hub (ATOM) chain doesn't seem to support HTLC and smart contracts at all (need to re-check it again).
2. HTLC is supported on IRIS docs: https://www.irisnet.org/docs/features/htlc.html#htlc.
3. JUNO has WASM smart contracts support https://docs.junonetwork.io/juno/home-of-cosmwasm.
4. EVMOS supports EVM contracts.

According to this, to swap the native ATOM, we will need to perform IBC transfer of it to one of these chains, lock there, and IBC back to Cosmos Hub when the swap is completed. It will require users to also have a native asset of the specific blockchain (e.g. IRIS) to pay IBC transfers fees, which might be inconvenient from an UX perspective. Though, I've not figured out a better solution for this yet.

@ozkanonur I think the plan is as follows for you:

1. Implement HTLC PoC on Iris testnet. https://www.irisnet.org/docs/get-started/testnet.html Do it for Iris itself and check if it works for IBC assets.

2. Recheck whether HTLC is activated on Cosmos Hub. You can ask on their Discord https://discord.com/invite/cosmosnetwork, and maybe we will get direct Cosmos developers contacts from CA.

• If HTLC works on native ATOM/Cosmos Hub, it would be perfect. We can proceed with swaps implementation on it.
• If not, we will likely need to create a special chain for AtomicDEX swaps in Cosmos ecosystem using Iris HTLC module. Discuss tokenomics, fees, etc. directly with CA.

[artemii235]

@ozkanonur

As you finished HTLC PoC for IRIS and tokens, we can proceed with further steps. For now, we can implement IRIS swaps and consider creating our own HTLC-enabled chain later (approved by @tonymorony and @ca333). It would be perfect to also demo IBC Atom swap in the coming two weeks, though I'm unsure if it's really feasible.

As per implementation, you can create a test similar to https://github.com/KomodoPlatform/atomicDEX-API/blob/c7dde3a0aeff113db4ba58cbfaa4da6926cd9612/mm2src/mm2_main/src/mm2_tests.rs#L963 to start the swap. You will get unimplemented panics on the various methods that you require to implement. For most of them, you can use dummy implementations (even for swap payments validation methods, since it's PoC) - we just need all swaps transactions to be sent and trading completed.

Please let me know if you need any assistance with it 🙂

[artemii235]

Checklist for the future:

• Add sha256 secret hash support for QRC20. Refactor the secret hash handling to Enum instead of checking its length. (Artem)
• Check if tx history can be fetched using Tendermint RPC. (Onur)
• Finish all TODO notes. (Onur)
• SPV validation of swap transactions
• Support memo field for Tendermint protocol coins/tokens withdrawal. (Onur)
• [r2r] cosmos swap p.o.c #1468 (comment) - use custom seed on each CI agent (Onur)
• [r2r] cosmos swap p.o.c #1468 (comment) (Artem)
• [r2r] cosmos swap p.o.c #1468 (comment) (Artem) - Refactor sha256 secret hash handling to support old ETH swap smart contract version.
• [r2r] cosmos swap p.o.c #1468 (comment) (Artem)
• Try to create a chain using Cosmos SDK with Iris HTLC support, connect it to testnet Cosmos HUB and setup IBC channel. (Onur)
• [r2r] cosmos ibc transfer implementation #1636 Cosmos ibc implementation (Onur)

[onur-ozkan]

Try to create a chain using Cosmos SDK with Iris HTLC support, connect it to testnet Cosmos HUB and setup IBC channel.

Is this part of the cosmos integration? It seemed like nucleus project is out of scope for this task.

[shamardy]

@onur-ozkan I think we can close this issue as completed. Only item left in the checklist is SPV validation of swap transactions and there is an issue opened for SPV for all protocols, and I added tendermint to the checklist there #1612 (comment).