Apple Encrypted Archive

From The Apple Wiki

Apple Encrypted Archive is a proprietary archive format that can compress, encrypt, and/or sign a file. Its magic number is the 4 ASCII characters "AEA1".

macOS Monterey ships an aea command line tool that can create and extract (decrypt) these archives (see aea manpage). They can also be handled with public Swift API and private C API in libAppleArchive.dylib.

It's notably used since iOS 15 for signed .shortcut files created in Shortcuts.