For ODF 1.1 encryption, SHA1 is used as the start-key digest algorithm
of PBKDF2.

For the ODF export password-to-modify "feature", PBKDF2 is used
without a start-key digest round, so the UTF-8 encoded password
is directly the input.

In both cases, if the user entered a password with a known problematic
length, reject it and request a new one.

Change-Id: Ie6510c1e668e1ed32be439ebe00354881b6ca83f