Tron

On Tron, H rides in the payer's own signed transaction: raw_data.data holds the 77 ASCII bytes lcp:sha256: followed by H, beside exactly one TRC-20 transfer(payTo, amount). The payer pays every fee: energy, bandwidth and the network's memo fee.

The facilitator needs a FullNode (it calls /wallet/triggerconstantcontract, /wallet/broadcasthex and /wallet/gettransactioninfobyid) and a Solidity node (/walletsolidity/gettransactioninfobyid and /walletsolidity/getnowblock). A java-tron node serves both, on HTTP ports 8090 and 8091 by default.

What /verify checksCopy Anchor Link

In order; the first failure is the answer.

1. The network is configured, and the requirements are ones the profile admits (its rule 1), else invalid_network or invalid_payment_requirements.
2. payload.transaction is a serialized Tron Transaction in hex that decodes to exactly one TriggerSmartContract whose data is an LCP sha256 string, else invalid_payload.
3. asset and payTo are Tron addresses, else invalid_payment_requirements.
4. The contract called is asset, and the call data is exactly transfer(payTo, amount), else invalid_payload.
5. The transaction carries exactly one signature, else unsupported_permission. That signature recovers to the transaction's owner, else invalid_payload. A multi-signature owner permission is not served.
6. expiration is in the future and no later than now plus maxTimeoutSeconds, else invalid_payload.
7. The FullNode's /wallet/triggerconstantcontract simulates the transfer without failure, else invalid_transaction. A node that does not answer gives unexpected_verify_error.

The answer is {isValid: true, payer}, with payer the owner in base58check.

What /settle doesCopy Anchor Link

1. Repeats every check of /verify.
2. Reads the stored answer for the transaction id. A final one is returned as it is, so a repeated /settle gets the first answer.
3. Claims the transaction id with one conditional insert, so concurrent settles of one payment broadcast once.
4. Broadcasts the signed bytes with /wallet/broadcasthex. A DUP_TRANSACTION_ERROR counts as broadcast.
5. Reads the receipt with gettransactioninfobyid every second. SUCCESS at the FullNode is success. Any other result is a failure only once the Solidity node, which serves solidified blocks alone, shows it. A transaction whose expiration has passed and that no node shows once the solidified head is two slots past it can never be included, and is answered invalid_transaction_state.
6. Stores the answer and returns it.

Success is {success: true, transaction, network, payer}, where transaction is the transaction id in hex.

Where H is on chainCopy Anchor Link

H is in raw_data.data, inside the bytes whose SHA-256 is the transaction id the payer signed. It is read by transaction id from a Solidity node. No index searches memos.