GitLab

Fix signature format

Previously this was decided by checking whether any of the scheme managers of any of the involved credetials and attributes that occur in the session uses a keyshare server. However, in case of disclosure and signing sessions, this could erroneously include attributes from disjunctions that have not been selected by the user.

Previously, an attribute disjunction erroneously either had no values for any of the
attributes, or it required a value for all attributes. A required value of null in an
attribute disjunction now specifies that the disjunction imposes no value on the attribute.