What is MIME type "application/pkcs7-signature"?

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

The MIME type application/pkcs7-signature is used for files that carry a digital signature made under the PKCS #7 standard. It contains cryptographic data that proves a message or document comes from a trusted source and has not been altered.
It works with systems that use public key cryptography. When a file is signed, it shows that the sender’s digital certificate validates the content. This process helps protect data integrity and authenticity.
Files using this MIME type often appear in secure communications and document exchanges. For example, secure email systems use it to verify that a message is genuine. Digital documents and software updates may include such signatures to show they are safe.

Authentication: Confirms the data’s origin.
Integrity Check: Ensures the content remains unchanged.
Email Security: Supports S/MIME, a protocol for secure email.
Document Signing: Validates the authenticity of signed files.

Files built on this standard include those with the container formats P7M and P7B, as well as standalone signature files like P7S.
For more technical details, see the PKCS #7 article on Wikipedia.

Associated file extensions

.p7m, .p7b, .p7s

Usage Examples

HTTP Header

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


    Content-Type: application/pkcs7-signature

HTML

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


    <a href="file.dat" type="application/pkcs7-signature">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/pkcs7-signature');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.p7m, .p7b, .p7s

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.