Frequently asked questions

Fundamentals

What is RFC 3161 timestamping?

An IETF standard for trusted timestamping: a Time Stamping Authority (TSA) cryptographically signs a hash of your content together with the current time. The resulting .tsr token is tamper-evident proof that the content existed, in exactly that form, at that moment — verifiable by anyone, forever, without trusting sigill.ai.

What seal formats does Sigill produce?

Three open ETSI formats: PAdES (embedded in PDFs), JAdES (detached, for JSON), and CAdES (detached, for any artifact you can hash deterministically). All carry an embedded RFC 3161 timestamp. The decision rule is short — see Choosing a seal format.

What is a .tsr file?

A Timestamp Response — the actual cryptographic token: your content's hash, the timestamp, the TSA's signature, and its certificate chain. Self-contained; verifies offline with standard tools like OpenSSL. Store it alongside the original content.

Does this hold up legally?

eIDAS gives electronic timestamps legal effect across the EU, and a qualified timestamp additionally enjoys a presumption of the accuracy of its time and the integrity of the bound data. Sigill's seals are advanced electronic seals (KMS-backed signing with platform or customer-controlled certificates); qualified timestamps are available on every operation with one flag — see Qualified timestamps for legal-grade evidence.

Privacy

Is my content ever sent to sigill.ai or a timestamp authority?

The platform is hash-first. Timestamping, detached CAdES/JAdES sealing, and delegated SDK PAdES sealing are fully hash-only — your content cannot reach us on those paths. The web app's PDF sealing flow, and the SDK upload fallback when you explicitly enable it, transmit the file so the seal can be applied server-side; it is processed in memory and never stored. Timestamp authorities only ever receive the digest to be timestamped.

What does sigill.ai store?

Digests, timestamp tokens, labels, certificate references, and operation metadata. Optionally — if your organisation enables it — the detached seal artifacts (.p7s/.jades.json), which contain signatures, never content. There is no document storage in the product. The Trust Center documents this formally.

Where is my data hosted?

AWS eu-north-1 (Stockholm, Sweden). All data remains in the EU. The service is operated by Sigill AS — see Compliance posture.

Usage

Which timestamping option should I choose?

tsaSlug: "auto" for Sigill-managed rotation with failover (the default and right answer for most). A verified bring-your-own TSA when your organisation must route through a specific authority. qualified: true when the proof needs eIDAS statutory weight.

Can seals carry my organisation's name?

Yes — bring your own certificate: your CA issues the certificate, the private key lives in hardware-backed KMS, and your subject appears in every verification report.

Can I verify without sigill.ai?

Completely. Every artifact is an open standard: OpenSSL for .tsr tokens, standard PDF readers for PAdES, the EU's DSS reference validator for everything — plus our free verifier, no account required. The full menu of options.

How do I integrate this into a pipeline or product?

Four surfaces: the REST API (hash it locally, POST the digest), the SDKs for Python and .NET (sealing included), MCP for AI agents, and the browser extension for AI conversations. CI stamping is a three-line addition to any pipeline.

Is Sigill quantum-safe?

Detached seals (CAdES/JAdES) support a hybrid ML-DSA-87 signature (NIST FIPS 204) alongside the classical one — one flag. Embedded PDF seals can't carry ML-DSA yet (no ETSI profile exists); give long-lived PDFs a detached hybrid seal alongside. The long-term strategy.

What happens if timestamping is unavailable?

auto mode fails over across multiple independent TSAs; if every source fails, the API returns a structured 502 and nothing is stored or charged. Seals degrade gracefully: a seal whose timestamp could not be embedded is still produced and marked at the corresponding level. Live status: status page.

Do timestamps expire?

TSA signing certificates do (typically 5–10 years) — the proof doesn't have to. Restamp existing tokens before certificate expiry to extend the chain of trust indefinitely: Evidence that outlives the infrastructure.