Sealgen – Create and Verify Digital Seals
Sealgen is a web-based tool for generating and verifying cryptographically secured 2D barcodes on travel and identity documents and other offical documents.
What are Visible Digital Seals?
Visible Digital Seals (VDS) are 2D barcodes printed directly onto a document. They contain essential document data in machine-readable form and are secured with a digital signature. This allows the content of a document to be verified at any time – without any database query, based solely on the barcode itself.
The principle is the same as with a digital certificate: anyone who knows the associated verification infrastructure can determine whether a seal is genuine and that the contained data is unchanged.
Sealgen supports two seal formats: VDS according to BSI TR-03137 / ICAO Doc 9303 Part 13 and IDB (ICAO Datastructure for Barcode) – both internationally recognised standards for official documents.
Scope
The focus is on seal types used or planned in Germany – example values and defaults reflect that context. That said, the underlying backend and the VdsTools library support everything defined in the international standards, so other document types and configurations can be explored freely.
Features
- Generate seals for various document types – with pre-filled sample data
- Read and decode existing seals and display their contents in plain text
- Cryptographic verification of digital signatures
- REST API access for direct integration into your own systems (API documentation)
Own Certificates and Keys
Registered users can store their own certificates and private keys in their profile. This allows seals to be signed with an individual key instead of the server-side default certificate.
Users without their own keys can still use Sealgen in full: in that case, the server signs with the test certificate UTTS5b, which is used exclusively for demonstration and development purposes and is not registered in any production verification infrastructure.
Under the Hood
Sealgen is built on the open-source library VdsTools – the same library that powers the mobile seal verification app Sealva. All encoding, signing, and verification runs in a backend service; the frontend communicates exclusively via a REST API.