SPV support

[mercadoa]

(blocked by transaction block format, chain header oracle)

Support SPV via a built-in function that recognizes a JSON payload of a particular format.

The JSON payload contains an SPV merkle proof of some receipt on another chain plus intermediate/connecting merkle roots leading to the executing chain.

[mercadoa]

➤ Lars Kuhtz commented:

The currently implemented SPV API doesn't require any intermediate/connection merkle roots.

This is the public API of Chainweb.Payload.SPV ( https://github.com/kadena-io/chainweb/blob/c9bb53fab1040193a23f32e25d4315b8221bb79b/src/Chainweb/Payload/SPV.hs#L17 ):

-- | Runs a transaction Proof. Returns the block hash on the target chain for
-- which inclusion is proven.

runTransactionProof :: TransactionProof SHA512t_256 -> BlockHash

-- | Verify a proof against the head of the target chain in the given CutDb. It guarantees that
-- the proof target Merkle hash is contained in the head of the target chain in the CutDb.

verifyTransactionProof
:: CutDb
-> TransactionProof SHA512t_256
-> IO Transaction

-- | Creates a witness that a transaction in is included in the head
-- of a chain in a chainweb.

createTransactionProof
:: PayloadCas cas
=> CutDb
-- ^ Block Header Database
-> PayloadDb cas
-- ^ Payload Database
-> ChainId
-- ^ target chain. The proof asserts that the subject
-- is included in the head of this chain.
-> ChainId
-- ^ source chain. This the chain of the subject
-> BlockHeight
-- ^ The block height of the transaction
-> Int
-- ^ The index of the transaction in the block
-> IO (TransactionProof SHA512t_256)

[mercadoa]

➤ Emily Pillmore commented:

Beginning this task as of tomorrow - syncing with Stuart today about requirements and the current status of SPV infra

[mercadoa]

Moved issue over to chainweb-node (108)