Luca Bruno Alice and Bob share hashed secret. Alice creates secret and hashes it, depositing Ethereum which is locked 48 hours (or any other arbitrarily chosen locktime period). Now Bob participates on Bitcoin side using timelocked conditional tx where he deposits bitcoin. Now alice can redeem this transaction by using her secret. After that Bob extracts the secret using Alice’s redemption transaction and hash she provided him. He can use this secret to redeem his ethereum. Similar in opposite direction.