Provenance

Provenance and Transactions Proofs

Provenance API give user access to key->value history, raw transaction data access and transactions existence proofs, that provide cryptographic proof of transaction existence in ledger.

// Provenance access to historical data and data integrity proofs
type Provenance interface {
	// GetProof returns two paths imn Merkle tree - one for transaction in block and one for block in ledger
	GetProof(txId []byte, height uint64) (*types.Proof, error)
	// GetHistory return full history for given key in db
	GetHistory(dbName, key string) ([]*types.HistoricalValue, error)
	// GetTransaction returns transaction envelope by its id
	GetTransaction(txId []byte) (*types.TransactionEnvelope, error)
}

As we can see here, the API is Blockchain DB installation level API, not single DB level API and it exposed by DBConnector

// DBConnector handle connectivity between sdk and Blockchain Database cluster
type DBConnector interface {
	...
	// GetProvenance returns blockchain db provenance interface
	GetProvenance() Provenance
}

If not mentioned otherwise, this document describes skip list based proofs for ledger consistency and integrity. For more detailed explanation, see Transaction-Proofs-Skiplist

As mentioned in Transaction document, during provenance data creation phase, {Key, newValue, BlockTime, BlockNumber, TxTime, TxId, ClientId, IsDelete, IsOk} tuple stored as provenance data for each key in WSet.

GetHistory returns slice of history values based on data stored in provenance tuple

message HistoricalValue {
  // DB key
  string key = 1;
  // Historical value
  bytes value = 2;
  // Client time for client who submitted transaction
  google.protobuf.Timestamp txTime = 3;
  // Sequencer time when block was created
  google.protobuf.Timestamp blocktime = 4;
  // Transaction that did the change
  bytes txId = 5;
  // Block number that holds changing tx
  uint64 blocknumber = 6;
  // Is this tx deleted this key
  bool isDelete = 7;
}