Document and invoice verification
Local fingerprint verification of a document to confirm its sealing and declared provenance before a sensitive action.
| Version | 2.0 — 15 September 2026 |
|---|---|
| Intended audience | Technical, security, integration and partner teams |
| Status | Technical description based on public information; implementation parameters to be confirmed |
Purpose and scope
Detect a modified invoice, substituted bank details or a document that no longer matches the sealed version, without uploading the full content to Seal.
Operating principle
Since v4.3.0: the issuer receives a CODE (D-XXXXXXXX) to print on the invoice or in the email, never a link; the recipient types seal.lifaio.com/doc themselves, enters the code and chooses the file. The verdict distinguishes: authentic, does not match (altered, or re-saved, converted, scanned), revoked (with the replacing code), expired, unknown. The issuer may set a validity in days, revoke a document in one click, and seal up to 1,000 fingerprints per API call. Verification is rate-limited per IP address.
- The verified issuer seals a specific version of the document.
- A fingerprint and the minimum necessary metadata are recorded under service policy.
- The recipient selects the file in the browser.
- The browser computes the fingerprint locally; the file itself is not sent to Seal.
- The result reports whether it matches the sealed version, who sealed it and the relevant date.
Targeted threats
- Modification of bank details
- Fraudulent invoice imitating a supplier
- Alteration of a contract or instruction
- Interception and substitution of an attachment
Components and responsibilities
| Component | Role |
|---|---|
| Verified organisation or publisher | Establishes identity, channels or domains and manages authorised people. |
| User or approver | Presents live evidence or participates in authorisation under policy. |
| Seal service | Evaluates necessary verification elements and returns a result limited to the use case. |
| Integrating system | Binds the Seal result to the exact action, applies business rules and retains required audit data. |
| Verifier | Checks the result in context and does not interpret it as a guarantee of truth. |
Data and privacy
The stated public principle is data minimisation: no GPS, biometrics or cameras for identity and presence modules; local browser computation when a media or document module processes a file; and retention of irreversible fingerprints and limited metadata rather than source content. The exact fields, retention periods, logs, subprocessors and transfers must be confirmed in a data-processing appendix.
Expected security properties
- Temporal freshness of live evidence
- Separation of roles and factors
- Binding of the result to the context or action
- Minimisation and non-disclosure of source content
- Proportionate traceability without turning Seal into a central identity database
Limitations and assumptions
- A document that was not sealed cannot be validated by this mechanism; absence of a seal does not prove fraud.
- A match proves integrity relative to the sealed version, not the truth of the content or economic legitimacy of the transaction.
- Canonicalisation rules, supported formats and behaviour after conversion must be defined.
Items to confirm before integration
- API, request and response schemas, authentication and quotas
- Applicable algorithms, key lengths, entropy sources and rotation
- Time tolerances, clock synchronisation and expiration handling
- Error handling, revocation, recovery and service continuity
- Logging, retention, location, deletion and regulatory obligations
- Penetration testing, independent cryptographic review and vulnerability disclosure process
Public references
- https://seal.lifaio.com/go
- https://lifaio.com/seal-lifaio/
Notice: this document describes the publicly communicated conceptual operation. It does not replace an API specification, cryptographic analysis or independent security audit.
UK patent applications pending: GB2619490.2 · GB2619948.9 · GB2620153.3 · GB2620211.9 · GB2620220.0 · GB2620253.1 · GB2620315.8 · GB2620629.2 · GB2621074.0 · GB2621382.7 · GB2622122.6 · GB2622135.8
