export async function verifyRegistration()

in src/GetRevision.ts [86:143]
51 lines of code
4 McCabe index (conditional complexity)

export async function verifyRegistration(
    txn: TransactionExecutor, 
    ledgerName: string, 
    vin: string,
    qldbClient: QLDB
): Promise<void> {
    log(`Let's verify the registration with VIN = ${vin}, in ledger = ${ledgerName}.`);
    const digest: GetDigestResponse = await getDigestResult(ledgerName, qldbClient);
    const digestBytes: Digest = digest.Digest;
    const digestTipAddress: ValueHolder = digest.DigestTipAddress;

    log(
        `Got a ledger digest: digest tip address = \n${valueHolderToString(digestTipAddress)},
        digest = \n${toBase64(<Uint8Array> digestBytes)}.`
    );
    log(`Querying the registration with VIN = ${vin} to verify each version of the registration...`);
    const resultList: dom.Value[] = await lookupRegistrationForVin(txn, vin);
    log("Getting a proof for the document.");

    for (const result of resultList) {
        const blockAddress: ValueHolder =  blockAddressToValueHolder(result);
        const documentId: string = getMetadataId(result);

        const revisionResponse: GetRevisionResponse = await getRevision(
            ledgerName, 
            documentId, 
            blockAddress, 
            digestTipAddress,
            qldbClient
        );

        const revision: dom.Value = dom.load(revisionResponse.Revision.IonText);
        const documentHash: Uint8Array = getBlobValue(revision, "hash");
        const proof: ValueHolder = revisionResponse.Proof;
        log(`Got back a proof: ${valueHolderToString(proof)}.`);

        let verified: boolean = verifyDocument(documentHash, digestBytes, proof);
        if (!verified) {
           throw new Error("Document revision is not verified.");
        } else {
            log("Success! The document is verified.");
        }
        const alteredDocumentHash: Uint8Array = flipRandomBit(documentHash);

        log(
            `Flipping one bit in the document's hash and assert that the document is NOT verified.
            The altered document hash is: ${toBase64(alteredDocumentHash)}`
        );
        verified = verifyDocument(alteredDocumentHash, digestBytes, proof);

        if (verified) {
            throw new Error("Expected altered document hash to not be verified against digest.");
        } else {
            log("Success! As expected flipping a bit in the document hash causes verification to fail.");
        }
        log(`Finished verifying the registration with VIN = ${vin} in ledger = ${ledgerName}.`);
    }
}