Swapping the ownership of two tokens on two accounts is a fundamental DeFi service. While swap atomicity in DEX is enforced by having two transfers done in a single transaction, there are practical scenarios where a swap of two accounts' ownership needs to be done in two transactions. An example is cross-chain swaps. In this lab, you will implement a multi-transaction swap using HTLC.
HTLC or hash time lock contract is parameterized by hash h, timeout t, sender account A and receiver account B. HTLC(h,t,A,B,2mToken) stores a deposit of 2 mTokens and there are two outcomes: 1) before the timeout t, if the HTLC smart contract receives receiver B's transaction revealing secret s such that h=H(s), the 2 mTokens will be transferred to B's account. 2) after the timeout t, if case 1) did not happen, the HTLC smart contract returns the deposit to sender A.
Your job is to implement HTLC smart contract.
An atomic multi-transaction swap can run based on two HTLC smart contracts. The protocol is described in the figure below.
Run the above atomic swap protocol based on your HTLC smart contracts implemented in Task 1.
- For all tasks, you should 1) submit your smart-contract code, and 2) show the screenshot of the program execution.