Documentation
Sigill creates portable cryptographic evidence for data, documents, and events: RFC 3161 timestamps, detached CAdES/JAdES seals, and PAdES PDF seals. Hash-first by design — most operations transmit nothing but a digest.
Architecture
Use Cases
Seal a PDF without uploading it
Delegated PAdES sealing: the SDK assembles the signature on your machine and sends sigill.ai a 32-byte digest. Full B-LTA output on Business and above, qualified timestamps, and a privacy guarantee enforced in code.
Seal AI and agent logs with JAdES
Make agent sessions, model outputs, and decision records provable: detached ETSI-standard JSON seals, hash-only by default, with optional post-quantum protection.
Create detached evidence with CAdES
Data, documents, events, logs, exports — a compact detached .p7s proving origin, integrity, and time for any artifact your system can hash deterministically, without the content ever leaving your systems.
Timestamp builds and releases in CI
Prove what your pipeline produced and when: hash the artifact in CI, send only the digest, archive the timestamp token next to the release. A few lines in any CI system.
Qualified timestamps for legal-grade evidence
When proof needs statutory weight: eIDAS-qualified timestamps from providers on the official EU trust list, one flag away on every timestamp and seal.
Seal under your own name (BYOC)
Bring a certificate issued to your organisation by the CA of your choice. Sigill generates and guards the private key in hardware-backed KMS — and your name appears on every seal.
Route timestamps through your own TSA (BYOT)
Some organisations are told exactly which timestamp authority to use. Register your own RFC 3161 endpoint, let Sigill verify it, and route stamps through it — with everything else unchanged.
Prove priority: IP, research, and designs
Establish that you had it first — designs, datasets, manuscripts, source trees — with a timestamp on a hash. The material never leaves your systems, and the proof outlives any dispute.
Let AI agents seal their own work (MCP)
Connect Sigill as an MCP server and agents timestamp, seal, and verify autonomously — every consequential action leaves tamper-evident evidence, without custom integration code.
Capture AI conversations as evidence
The browser extension records tamper-evident proof of what an AI assistant was asked and what it answered — on Claude, ChatGPT, and Gemini — timestamped turn by turn, with content hashed on your side.
Evidence that outlives the infrastructure
Certificates expire, TSAs shut down, algorithms weaken. How B-LTA seals, archival restamping, and the post-quantum hybrid keep today's proofs verifiable for decades.
Verify a seal without a Sigill account
Every seal and timestamp we produce is an open-standard artifact. Here is how to verify one with our free verifier, with OpenSSL, with PDF readers, or with the EU's reference validator — no account, no lock-in.
Concepts
API
Timestamping
RFC 3161 timestamps by hash — the file never leaves your machine.
Seals
PAdES, CAdES, and JAdES sealing, including the hash-only endpoints.
Lookup & history
Find proofs by hash, list operations, download evidence.
Timestamp Authorities
Automatic selection, qualified options, and bring-your-own TSA.