Fix #87: security helper converted into component and improved

Fix #87: security helper improvement

Migrated from #4052
@tom--, so you confirm that both current derive strategies produces the same result? What about your comment at #4131:

> With the 25-byte key, both strategies seem to produce the same key but using 'pbkdf2' the key is truncated to 20 bytes

Are you sure it is safe to use silent fallback in this case?