But the whole encryption_algorithm stuff seems not well thought out in any case.

This was introduced because we can't assume that all installations will install openSSL especially on Windows, thus encryption should work

with bundled yaSSL also. Do you have some better suggestion ?

Yes, I assumed so, but the current implementation is lazy and user-hostile. And, to me, having a single global variable controlling "the" encryption algorithm (for what, exactly?) is weird. Presumably if it makes sense to have it changeable, it also makes sense to set different algorithms for different objects.

At a minimum, IMHO: store the encryption_algorithm selection with each encrypted object so that data can be migrated in the future. Then, implement sufficient support in the various necessary places so that it can be safely changed. Currently as far as I can tell it is globally set once, and impossible to change in the future. This could be done via stealing some bits from either the stored encryption scheme (1 byte) or key version (4 bytes) or adding a new encryption algorithm field which is stored alongside those everywhere (this is probably the best strategy IMHO, but takes a bit of thought).

Alternatively as an absolute (and even lower) minimum: ensure that changing it once the database is initialized produces a loud and very clear error message to the user.

Regards,

Jeremy