PKPASS is a file format for storage and exchange of digital passes developed by Apple for its Wallet application. Passes can replace physical paper or plastic cards, like a payment card, boarding pass, loyalty card or coupon. The format specification has been published online and this allowed for compatible implementations to be developed for other platforms like Android, Windows and Linux.
The file is a ZIP archive with a filename extension <code>.pkpass</code> containing a set of digitally signed files describing the digital pass. Multiple <code>.pkpass</code> files can be further combined into a single ZIP archive with an extension of <code>.pkpasses</code> in order to combine several digital passes for ease of distribution.
The file contents of a sample PKPASS file might look like this:
<code>icon.png</code> is the digital pass icon. <code>logo.png</code> is displayed at the top left of the rendered pass.
Localized resources - like images and strings - are stored in subfolders named like this: <code><language_identifier>-<region_identifier>.lproj</code>
The file <code>pass.json</code> is a JSON formatted dictionary describing the digital pass.
<code>manifest.json</code> contains a JSON dictionary containing SHA-1 hashes for all files except the manifest itself and the signature.
<code>signature</code> contains a PKCS #7 signature of the manifest file thus effectively signing all files in the bundle.