Portable database for storing secrets
You could also have a look at SQL Server Compact edition, which only requires a DLL and will store the data in a single file, just like SQLite or Access, Firebird, etc.
It also has encryption capabilities built-in.
Some references:
- Security and Encryption for SQL Server Compact
- Tutorials on using SQL Server Compact Edition (second and third sections down the page).
Password encryption
See my answer to your other question os SO.
There is a project called sqlite-crypt. Which should be your best bet. sqlite db with all data on disk encrypted.