crx download link parsing

Introduction

CRX files are Chrome browser plugin files, or Chrome extensions, primarily used to enhance various functionalities of the Chrome browser. CRX files are saved in a compressed format and may contain files like .js, .json, images, and executable programs. Common plugins include mini-games, ad blockers, screenshot tools, translation, etc.

CRX file format, with additional info in ZIP file header; simply renaming to ZIP might not allow extraction.

Encoding rules:
    43 72 32 34   # "Cr24" -- the magic number
    02 00 00 00   # 2 -- the crx format version number
    A2 00 00 00   # 162 -- length of public key in bytes
    80 00 00 00   # 128 -- length of signature in bytes
    ...........   # the contents of the public key
    ........