What is MIME type "application/x-ddoc"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

application/x-ddoc is a MIME type that signals a file used in digital signature technology. It designates a file that bundles a digital signature with its associated document content.

Files of this type—such as the DDOC—often follow digital signature standards used in secure document exchanges.

Primary Function: It wraps digital signature data together with a document. This ensures that any alterations are detectable.
Security: It supports verification processes to confirm a document’s authenticity and integrity.
Usage: It is employed by digital signature systems, often as part of electronic identification and secure document workflows.
Integration: Reader applications use this MIME type to apply the correct protocols for signature validation and document processing.

This MIME type directs software on how to handle files that contain embedded security information. It is integral for systems managing trust and verification. For more in-depth details on file types and their applications, visit Filext.

Associated file extensions

.ddoc

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: application/x-ddoc

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="application/x-ddoc">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'application/x-ddoc');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.ddoc

FAQs

What is an application/x-ddoc file?

An application/x-ddoc file is a container used for digitally signed documents, most notably associated with the legacy DigiDoc format. It bundles the original file (such as a PDF or text document) along with cryptographic signatures to ensure authenticity and integrity. You can learn more about the specific extension at ddoc.

How do I open a .ddoc file?

You cannot open a .ddoc file with a standard text editor or web browser. You typically need specific ID-software or a DigiDoc client (common in Estonia and Baltic states) to verify the digital signatures and extract the signed files contained within the wrapper.

How do I configure Apache to serve .ddoc files?

To ensure your Apache server correctly identifies these files and prompts a download, add the following line to your .htaccess file or main configuration: AddType application/x-ddoc .ddoc. This prevents the browser from trying to interpret the binary signature data as text.

Why does my browser download the file instead of displaying it?

Browsers like Chrome, Firefox, and Edge do not have native support for rendering application/x-ddoc digital signature containers. As a result, they treat the MIME type as an unknown binary application and default to downloading the file so it can be handled by a desktop application.

Is application/x-ddoc the current standard for digital signatures?

The .ddoc format is considered a legacy generation of digital signature containers. Modern systems have largely migrated to newer standards like .bdoc or .asice (Associated Signature Containers), which offer improved compatibility with international standards like eIDAS.

What does the 'x-' prefix mean in this MIME type?

The x- prefix in application/x-ddoc indicates that it is a non-standard or experimental type that was not originally registered in the IANA public MIME registry. It was defined specifically for the software ecosystem handling these digital signatures.

How do I add support for application/x-ddoc in Nginx?

To configure Nginx to serve this content type correctly, locate your mime.types file or the types block in your nginx.conf and add the entry: application/x-ddoc ddoc;. Reload Nginx to apply the changes.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.