InDesign's Lock File (.idlk) Naming Convention

I'd like to know the convention for naming .idlk files generated by InDesign.
When opening an indd file, I want to determine if the file is already in use by someone else, but this is problematic due to the idlk naming convention.
The idlk file name follows the following convention:
~<file name>~<Hash>.idlk

If the file name is too long, it will be truncated.
The standard length for truncation is 18 characters, but it seems to vary depending on the user's encoding.
For example, alphanumeric characters are 18 characters, but in other languages, the length is not simply the number of characters.
I'd like to know if this is determined by the user's system encoding or if there are fixed encoding conventions.
 

Furthermore, if there are multiple long files, the truncated file names will all be the same.
In this case, I need to check the hash value, but I don't have the information to determine the hash value.
I'd like to know the criteria for determining the hash value or the generation convention.

Thank you