Chrome extension id algorithm for local folder

Question

What is the algorithm of extension id in Chrome for local folders? For instance, given extension inside /usr/mychromeextension , how I calculate its extension id ?

Answer 1

According to the source code in id_util.cc:

1. SHA256 of the full path without trailing slash is calculated as a lowercase hex string.
   • in Windows the drive letter is uppercased if the path starts with one
   • in Windows UTF-16 encoding is used for the file path
2. the first 32 hex digits of the hash string are used

3. each hex digit is mapped from 0..f to a..p range:
   the decimal value of each hex digit is added to the ASCII code of lowercase a (97 decimal)

   We use the characters 'a'-'p' instead of '0'-'f' to avoid ever having a completely numeric host, since some software interprets that as an IP address.