ASUS Superset ZIP decryptor

You might think I have a personal vendetta against ASUS.
...maybe I do. So what.

Scheme details

To package the data in the way ASUS do:

0. Split a regular ZIP file into two at the point where ZIP central directory ends.
1. Calculate a 32-bit checksum for that data (no clue what that checksum might be, maybe CRC32), add it as little-endian bytes to the end of central directory section.
2. Encrypt the central directory section using whatever RSA public key ASUS use. I don't give a shit what it might be.
3. Write the encrypted section down to disk with .enc extension.
4. Write the remainder of the data to disk with .dat extension.
5. Package both files into another ZIP (smart af).

To reconstruct the ZIP into a proper, browsable one look into SupersetZip.cs file in this repository.

What in the ever-loving-fuck is the purpose of that scheme probably only people at ASUS' S/W department know.
What I know is I wouldn't want to touch that department with a 10-yard stick.