Appendix: Worked Examples
Every example below is a process whose parties reconcile after the fact today, and in each one the dispute or audit instead starts from a history every party already holds. The examples share one arrangement. Keys held by people, devices, and software sign the entries, and the file carries only a hash of each document (Payload Hash). Each party that may later need to prove something keeps the documents it has a right to hold and the enrolment evidence for each signing key (What Each Check Needs).
Each entry can leave the system that collected it. A party who arrives later, such as an auditor, checks the history with an open verifier (5 Open Protocol) and does not need the application that produced it. Because every step enters the history, it keeps details whose importance nobody saw at the time.
Every Reading Behind the Bill
Suppose a commercial customer disputes one quarter of its electricity bill. Its supplier answers with the history of every fifteen-minute reading behind the total. Each reading carries a signature from a key associated with the meter, and the customer checks the disputed readings, without access to the supplier’s billing system. A supplier can send that history with every bill and make checkable measurements part of its service.
The supplier’s signed report identifies the exact reading entries it used. With authorised access, the customer retains the measurement contents alongside the history. A later assessor can check those readings against their signed entries and the report, without asking the supplier to reconstruct the evidence.
That evidence lets the parties locate a disputed reading, but its signature does not establish that the measurement was correct. The parties examine the evidence that links the signing key to the meter. Calibration records and physical inspection help assess whether the meter measured correctly at the right point.1
Every Estimate Behind a Claim
Picture a policyholder who disputes a car-repair settlement lower than the repairer’s estimate. The insurer and the policyholder hold the same history of the claim: the photographs the policyholder sent, the repairer’s first estimate, the revised estimate after inspection, the assessment that recommended the settlement, and the adjuster’s approval. Both sides see which estimate the recommendation used, so the dispute starts from the evidence. An insurer can build that history for every claim as the claim develops.2
The recommendation names the revised estimate it used, and the approval names that recommendation; entry order alone does not show which evidence a decision used. A later correction adds a signed entry and keeps the earlier decision’s basis in view.3
A reviewer investigating a discrepancy can trace it to the contribution that introduced it, and the signature on that contribution shows which key signed it, so the party bound to that key answers for it.
Every Document Handed to an AI Supplier
Imagine an enterprise that sends confidential design documents to an AI supplier for an automated review. The contract lets the supplier analyse the documents for the enterprise, and forbids it to train shared models on them or to disclose them to other customers. On receipt, the supplier signs an acknowledgment of the exact document version and those terms, and the enterprise keeps it. An enterprise can collect that acknowledgment for every version and permission change, and keep the evidence of what each supplier accepted after the relationship ends.
The concern is common: in Cisco’s 2024 Data Privacy Benchmark Study, 68% of 2,600 privacy and security professionals cited disclosure to the public or to competitors as a concern about generative AI (Cisco 2024).
The acknowledgment completes a two-party agreement, which Cryptographically Bound Contracts calls a Cryptographically Bound Contract (CBC): the enterprise’s entry offers the documents under the terms, and the supplier’s signed entry accepts them. The enterprise’s own entry shows only what the enterprise sent; the supplier’s signature makes the receipt evidence of what the supplier accepted.4 Each acceptance references the exact offer, even if other entries fall between them in the history.
If another customer’s output later reproduces a distinctive confidential passage, the enterprise’s reviewer checks the retained documents against their hashes and compares the passage with that output and its full prompting context. Researchers extracted training data from the production language models they studied (Nasr et al. 2023). The contract’s dispute process decides whether the supplier breached it, and the enterprise brings the evidence it already holds: the supplier’s acknowledgment of the particular material and the restrictions it accepted.
Every Check Behind a Mortgage
Consider a lender that approves a mortgage after the valuer revises the valuation, because a new search found a right of way across the land. Years later, at refinancing, a reviewer asks which valuation the approval relied on. The history answers: both valuations remain as signed entries, and the approval references the revised one. A buyer or lender can keep that evidence for every property decision as the work happens, including the checks and revisions that never appear in the final approval.
Four contributors build the evidence behind an approval like this one (Table 1).5
| Contributor | Evidence retained |
|---|---|
| Identity checker | Signed checks, result and references to identity evidence |
| Title reviewer | Signed search findings, source, date and unresolved issues |
| Valuer | Signed valuation versions, assumptions and supporting material |
| Approver | Signed decision referencing the evidence relied on |
Every Handoff of a Part
Between January 2019 and July 2023, the UK parts trader AOG Technics sold more than 60,000 aircraft engine parts with forged Authorised Release Certificates, the documents that guarantee airworthiness. Its director doctored genuine certificates, and customers received documents carrying the signatures of sales and quality managers who did not exist. The fraud left planes grounded in the UK and worldwide, with estimated losses of more than £39.3 million for airlines, and came to light after an airline asked the aircraft equipment manufacturer Safran to check the authenticity of one part (Serious Fraud Office 2026). If the maker or maintenance organisation signs each release and handoff of a part, and the buyer can link that key to the organisation through an accepted key registry (What a Signature Proves), the buyer can check the chain before fitting the part. A doctored certificate then fails the signature check, and a manager who does not exist has no key bound to them.
The same evidence serves any asset owner who inherits equipment: the inspection findings, corrections, and handoffs that people sign as routine work proceeds.
For a compressor, an inspector’s finding and the fabricator’s correction remain in the history together, and a later approval references the evidence it accepted without removing the earlier finding, as in the claim example. Each custody transfer leaves an offer and a signed acceptance, as in the AI example; the pair shows what the parties accepted and does not by itself prove physical delivery or equipment condition. The next owner inherits the history and authorised access to the supporting material. Before the purchase closes it checks its copy against the latest heartbeat (Hub Heartbeat), and after a failure it traces which findings and approvals preceded it.
A digital product passport (a product record shared with parties such as repairers and recyclers) can present selected information from the same history, so a repairer can examine maintenance evidence or a recycler retrieve the material information it may see. The EU’s Ecodesign for Sustainable Products Regulation provides for passport information shared under access rights that differ by product group (European Parliament and Council 2024). The passport application decides who may see what and whether it meets the applicable requirements; EventChain supplies the signed history beneath it, so later checks need not depend on the original passport portal.
Tying the key to the installed meter takes enrolment or attestation evidence that the parties retain, and commissioning evidence that ties the meter to its measurement point.↩︎
Insurance fraud is the wider context: in 2022 the Coalition Against Insurance Fraud, funded by insurers and consumer groups, estimated annual insurance fraud in the United States at $308.6 billion across all lines (Coalition Against Insurance Fraud 2022). The coalition builds the total from earlier estimates and says the actual cost is impossible to measure accurately.↩︎
A software signature shows that the assessment service’s key signed the recommendation; showing which code or model produced the recommendation takes further deployment or attestation evidence.↩︎
An automated receipt shows that the signing key signed the acknowledgment. Linking that key to the supplier and its authority takes further evidence. The signature does not show which model or code handled the documents.↩︎
Identity checkers already keep evidence of their checks. In England and Wales, HM Land Registry contacts conveyancers and other checkers to check that a form in their name is genuine, and its guidance says it is important to keep a record of anyone whose identity they verified (HM Land Registry 2026).↩︎