> in-house _modified_ _mainstream_ encryption algorithm
Why would a company without cryptographic expertise modifying an existing algorithm without any particular goal in mind just to be different, produce something more secure than the winning solution in an open cryptographic competition?
> directory names
And file structure too, preferably. Incremental sync could be done with XTS mode.
You need only cryptographic common sense: it seems you have no idea how much it is easy to modify a mainstream cryptographic software to add basic and robust cryptographic modifications...
Are you an AI?