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ADOC format: how to open and sign an ADOC document
ADOC (the Lithuanian national signed-document format) is the electronic document format used by Lithuanian public institutions. Here you will find what it actually is, how to open an .adoc file you received, and how to create and sign an ADOC document yourself with a qualified electronic signature (QES).
What is ADOC?
ADOC-V1.0 is the Lithuanian electronic document specification approved in 2009. An ADOC file is not "a document with a signature in the margin" but a container: a single .adoc file packs the content itself (for example, a PDF or text), the mandatory metadata (who, when, on what basis) and electronic signatures in the XAdES format.
The format is used by the Centre of Registers (Registrų centras), courts, municipalities and other public institutions – if an institution asks for a "signed ADOC", a plain signed PDF will not satisfy it.
How to open an .adoc file?
A regular PDF reader will not open an ADOC, because technically it is a ZIP archive with a fixed internal structure. Your options:
- Through a signing service – you upload the .adoc and see the content, the metadata and who signed. Tvarka Sign opens ADOC and lets you extract the files inside.
- Manually – rename the file to .zip and you will see the files in the archive, but you cannot verify signature validity that way, and changing the content will break the document.
How to create and sign an ADOC?
The Tvarka Sign ADOC wizard does the heavy lifting for you:
- You upload a document or several files.
- The wizard builds an ADOC-V1.0 container with the mandatory metadata.
- You sign with a QES: Smart-ID, Mobile-ID, LT ID, a USB/eID card, or by tapping your ID card on your phone (NFC).
- You download the finished .adoc – ready to submit to the institution.
The wizard costs nothing – you pay only for a successful qualified signing according to the pricing.
Frequently asked questions
ADOC or PDF – which one to choose?
Between businesses, a signed PDF or an ASiC-E container is the most convenient. Choose ADOC when you will submit the document to a public institution that requires this format.
Can one ADOC hold several files?
Yes – ADOC is a container, so one signed document can hold the main document and its annexes.
Is an ADOC signature legally valid?
Yes. The QES used inside an ADOC has, under the eIDAS Regulation, the same legal force as a handwritten signature.
You reach the wizard after signing in with your electronic signature – this ensures the document is signed by a person with a verified identity.