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.ASICS file extension

To open .ASICS files on Windows, install a trusted ASiC-compatible application, such as DigiDoc4 Client or e-Szigno if it is used in your workflow.

To open a .ASICS file, use software that supports ETSI Associated Signature Containers, such as DigiDoc4 Client, e-Szigno, or a DSS-compatible signature validation tool provided by your organization. The file may look like an archive, but the important step is validating the contained signature or timestamp.

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Last updated: April 29, 2026 · Reviewed by Julian Stricker

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .ASICS files

Use these platform-specific instructions to open .ASICS files safely.

Windows

  1. Install a trusted ASiC-compatible application, such as DigiDoc4 Client or e-Szigno if it is used in your workflow.
  2. Right-click the .ASICS file, choose Open with, and select the ASiC/DigiDoc application.
  3. Use the application's validation or signature-details view to check the signer, timestamp, certificate status, and whether the container is valid.
Full Windows guide

Mac

  1. macOS does not normally provide built-in ASiC-S signature validation for .ASICS files.
  2. Open the file with an ASiC/DigiDoc-compatible desktop application available to you, or use a trusted DSS-compatible validation service supplied by your organization.
  3. If the file only opens as a ZIP archive, do not treat that as signature validation; use a proper ASiC validator.
Full Mac guide

Linux

  1. Linux desktop environments usually do not include native .ASICS validation.
  2. Use an ASiC-compatible tool or service used by your organization, such as software based on DigiDoc4j or the European Commission DSS library.
  3. After opening, verify the reported signature status instead of only extracting the archived data file.
Full Linux guide

iOS

  1. iOS/iPadOS Files or Quick Look may not understand .ASICS signature containers.
  2. Share the file to a trusted signing or validation app/service if your organization provides one, or transfer it to a desktop system with ASiC-compatible software.
Full iOS guide

Android

  1. Android usually has no built-in .ASICS validation.
  2. Open the file with a trusted signing or validation app/service if one is provided for your workflow, or move it to a desktop computer with ASiC-compatible software.
Full Android guide

Security notes

  • A valid ASiC signature can prove integrity and signer information, but it does not guarantee that the signed document itself is harmless; the contained data object can be any file type.
  • Do not rely on a generic ZIP viewer to decide whether the file is authentic. Use an ASiC-aware validator that checks signatures, timestamps, certificates, and revocation status.
  • Keep the original container intact. Editing, extracting, recompressing, or renaming contents may break the signature relationship or make later validation impossible.
  • Treat unexpected .ASICS files cautiously, especially if the contained document asks you to open macros, executables, scripts, or external links.

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Can't open this file?

These are the most common causes and fixes when .ASICS files fail to open.

Common reasons

  • The file opens like a ZIP archive instead of a signed document
  • No app is associated with .ASICS
  • Signature validation fails
  • Renaming to .zip or extracting changes the workflow

Fix steps

  1. Open the file in ASiC/DigiDoc-compatible validation software.
  2. Check the validation result, signer information, timestamp, and certificate status.
  3. Do not assume the extracted document is trustworthy unless the container validates successfully.

OS-specific troubleshooting

What is a .ASICS file?

.ASICS is the file extension for an ASiC-S, or Simple Associated Signature Container, standardized by ETSI. It is a ZIP-based container for one data object together with associated electronic signatures, timestamps, or evidence records. Its registered MIME type is application/vnd.etsi.asic-s+zip.

Background

ASiC stands for Associated Signature Containers. The format is used to bind documents or other data objects to electronic signatures or timestamps in a standard container, so that signature validation software can check who signed the data and whether it has changed.

Common MIME types: application/vnd.etsi.asic-s+zip

Further reading

Authoritative resources for more details on the .ASICS format.

Common .ASICS issues

The file opens like a ZIP archive instead of a signed document

ASiC-S containers are ZIP-based, so generic archive tools may list or extract their contents, but they will not validate the electronic signature.

  1. Open the file in ASiC/DigiDoc-compatible validation software.
  2. Check the validation result, signer information, timestamp, and certificate status.
  3. Do not assume the extracted document is trustworthy unless the container validates successfully.

No app is associated with .ASICS

The operating system may not know which program handles ASiC-S containers.

  1. Install or access a trusted ASiC-compatible validator, such as DigiDoc4 Client, e-Szigno, or a DSS-based service used by your organization.
  2. Use Open with to select that application.
  3. If you received the file from a government, bank, or business workflow, ask the sender which validator they expect you to use.

Signature validation fails

The container or its data may have been modified, the download may be incomplete, or the validator may be unable to check certificate or timestamp information.

  1. Download or request the file again without editing or extracting and repackaging it.
  2. Try validation while connected to the internet, because certificate and revocation checks may require online access.
  3. Ask the sender for a fresh container if the validator reports that the data or signature has been altered.

Renaming to .zip or extracting changes the workflow

Although the format is ZIP-based, changing the extension or repackaging the contents can break the expected ASiC structure or invalidate checks.

  1. Keep the original .ASICS file unchanged for validation and archiving.
  2. If you need the contained document, export or extract it from a trusted ASiC application after validation.
  3. Do not create a new .ASICS file by manually zipping files unless your signing software specifically supports that workflow.

FAQ

Is .ASICS the same as a normal ZIP file?

No. It is ZIP-based, but it follows the ETSI ASiC-S structure for one data object with signatures or timestamps. A ZIP tool may extract files, but it will not validate the signature correctly.

What MIME type is used for .ASICS?

The registered MIME type for ETSI ASiC-S containers is application/vnd.etsi.asic-s+zip.

Can I convert a document to .ASICS by renaming it?

No. Renaming only changes the file extension. To create a valid .ASICS container, use signing software or a service that explicitly supports ASiC-S creation.

What is the difference between viewing and validating a .ASICS file?

Viewing or extracting shows the contained data file. Validating checks whether the container's signature or timestamp is cryptographically valid and whether the signed data has changed.

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