Proof of Existence of a Block

Path in ledger query

This type of query is used to prove that block X is connected to block Y, based on skip chain hashes. The query result contains a list of block headers, including block X, connecting blocks, and block Y. X > Y, because connectivity in skip chains, like in all blockchains, is from the latter block to the earlier one. For more information about ledger consistency, see Block Skip Chain and Block Structure.

For more details on the full Ledger API exposed by the Orion Go SDK, see here.

Ledger data access example

The attached simple code snippet shows how to call block retrieval and ledger connectivity validation APIs from the SDK:

Please note: For presentation purposes, all results and error handling, except proofs, were eliminated.

    txId := "Tx000" 
    db, err := bcdb.Create(conConf)
    session, err := db.Session(&c.SessionConfig)
    ledger, err := session.Ledger()

// Get block header for block 5"
blockHeader, err := ledger.GetBlockHeader(5)

// Get transaction receipt for txId
txReceipt, err := ledger.GetTransactionReceipt(txId)

// Get the shortest path in ledger skip list between blocks and verify it
path, err := ledger.GetLedgerPath(1, txReceipt.Header.BaseHeader.Number)
res, err := bcdb.VerifyLedgerPath(path)

if !res {
    fmt.Printf("Block %d is not part of ledger\n", txReceipt.Header.BaseHeader.Number)
}