How to calculate PublisherID from Publisher?

Question

I'd like to know something about Windows Store and APPX package internals. The package.appxmanifest has an `` element that has a package name, publisher and version attributes, for example ``` ``` Apparently, when I open this manifest in VS2013 and go to Packaging tab, it shows me a read-only "Package Family Name" field, which is a concatenation of package name, underscore and something that looks like a strange hash of the publisher string. ``` MyCompany.MyGreatApp_f08ys7xx9zb3y ``` How do I calculate this hash (also known as PublisherId)? See also PackageId class or PACKAGE_ID structure. Here are some sample values for you eager cryptanalysts. It is 13 lowercase letters and digits, so the approximate "quality" is 67 bits. Thank you! ``` 8wekyb3d8bbwe CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US amge560j0aq9g CN=C357A519-CEE3-467…

Accepted Answer

I was very close in my guess of how the PublisherId value is constructed. I heard some whispering...

The value is a Crockford’s Base32 encoding of the first eight bytes of SHA-256 hash of the publisher string in UTF-16 (little endian). I have a good implementation that I validated using the sample values from my question.

How to calculate PublisherID from Publisher?

Solution

Problem