ASiC stands for Associated Signature Containers. It is a European standard for packaging one or more documents with their electronic signatures and related validation information in a single file.

Think of an ASiC file as a secure, signed package: it keeps the documents and the signatures that apply to them together, making the package easier to share, store, and verify.

ASiC is commonly used in the European e-signature ecosystem. In Estonia, ASiC containers are commonly encountered as .asice files and are used with digital-signature software such as DigiDoc.

ASiC is a technical container format, not a signature level on its own. Whether a signed ASiC file meets a particular legal requirement depends on the electronic signature inside it, the identity-verification method, and the applicable law.

ASiC is an ETSI standard and is among the recognised formats for advanced electronic signatures and seals under the EU eIDAS framework. When an ASiC container holds a qualified electronic signature, that signature has the legal effect set out in eIDAS across the EU.

An ASiC file is ZIP-based, but it should be treated as one signed container. It typically contains:

The signature is linked to the exact document content. Changing a file inside the container, adding or removing files, or repackaging the container can invalidate the signature or make the original signed state impossible to verify.

The ASiC standard has two main container types:

ASiC-S (Simple) is designed for one signed data object. It can include one or more signatures or time assertions that relate to that object.

ASiC-E (Extended) can package multiple documents and multiple signature or time-assertion files. It is well suited to agreements and other workflows involving several documents or signers.

Agrello creates ASiC-E containers with XAdES signatures. ASiC is the package; XAdES is the XML-based electronic-signature format contained within it.

Use an electronic-signature application or service that supports ASiC. We’ll list some most commonly used ones here.

You can technically inspect an ASiC file as a ZIP archive, but extracting or editing its contents is not a way to verify the signature. Use a compatible validation tool to check the signers, signature validity, signing time, certificate information, and whether the signed documents have changed.

You may see ASiC files with extensions such as .asice or .asics. The extension indicates the container type, while the files inside can be many common document types.

When sharing a signed ASiC container: