Seal PDFs Securely. Keep Files Where They Are
Keep PDFs in your environment while we apply Adobe-aligned, tamper-evident seals. Non-exportable keys locked in FIPS 140-3 HSMs; zero-trust access by design.
PDFs never leave your servers. We seal using SHA-256 digests—content stays private.
Non-exportable signing keys secured in FIPS 140-3 Level 3 HSMs.
Adobe Acrobat trusted; eIDAS aligned behaviors for regulated use cases.
Network isolation, mutual TLS, and least-privilege access at every layer.
Secure by Design
A single-command sealing service that keeps PDFs inside your security boundary, while our keys stay locked in FIPS 140-3 Level 3 HSMs. Publisher - Trusted PDf Sealing delivers audit-ready proof of authenticity and slashes fraud risk — protecting revenue, reputation, and future compliance without adding operational burden.
Provable Trust
The security of your data isn’t just a feature — it’s foundational. We don’t need a copy of your document to vouch for your seal. From our command-line tools to our cryptographic key infrastructure, every layer of our system is built with zero trust principles, clear boundaries, and hardened infrastructure. Eliminate a high-value attack surface by sealing documents in-place while meeting FIPS 140-3 and global certificate standards.•
Audit-ready seals, built on FIPS-validated hardware and globally trusted certificates.
Software and System Design
CLI
Security-forward by default: sends only what’s required to seal, nothing more.
- Local SHA-256 digest created on your machine; the PDF itself is never uploaded
- HMAC-SHA-256 is computed with your API Key to prove authenticity and freshness
- HTTPS-only transport protects confidentiality and integrity in transit
- No overreach: the CLI sends just the digest, HMAC, and a UTC timestamp — never your documents
API
Built to minimize attack surface and keep operations predictable (see API documentation):
- Least privilege access at every layer is enforced at every layer — services, IAM roles, and internal processes
- Separation of concerns: each component does one job, securely
- Modular architecture: rapid patching and safe isolation of components
- Ephemeral compute:: disposable workloads; no persistent state
- Zero trust requests: everything is authenticated; client data is untrusted and verified server-side
Keys
Granular control over how sealing runs in your environment:
- 160-bit cryptographically secure random keys
- Scoped access: allowed IPs, time windows, rate limits, and expirations
- Audit-friendly: each key usage is logged and tied to the action it authorized; logs are immutable
- Encrypted at rest: keys are encrypted with an HSM-hosted key and only decrypted by the PDF-signing service.
Architecture
Built for strict isolation and predictable compliance:
- Network-isolated: Private VPC; no public internet exposure and tightly scoped ingress.
- TLS everywhere All service-to-service calls require mutual TLS.
- Key never leave the HSM: All signing happens on-device; material is non-exportable.
- FIPS 140-3 Level 3 HSMs High-assurance custody for cryptographic keys.
Signing Logic
Standards-based seals that validate in Acrobat/Reader or any PAdES-compliant reader
- CMS/PKCS#7 from your SHA-256 digest We sign the hash you provide.
- Certificate chain embedded Adobe-aligned validation; optional LTV adds timestamp + revocation data.
- Timestamps Request times are recorded; RFC 3161 TSA inside the PDF is optional.
- WORM logs Every signing event is immutably recorded (write-once, read-many).
Frequently Asked Questions
How secure are PDF digital signatures?
How do you keep our document content secure?
What compliance standards do you meet?
Is this an e-signature workflow tool?
Want peace of mind?
Trusted Signatures provides the fastest, most affordable, secure PDF signatures on the internet.