0335304E The message-digest authenticated attribute is not allowed.

Explanation
The set of authenticated attributes that are supplied
from the attributes_signers parameter must NOT
include the message-digest authenticated attribute as this is automatically
provided by gsk_make_signed_data_content_extended() and gsk_make_signed_data_msg_extended().

User response
Do not include content-type or message-digest
in the set of authenticated attributes that are supplied to gsk_make_signed_data_content_extended() or gsk_make_signed_data_msg_extended().