All interfaces (data types and functions) of the library are defined in the header file ksba.h. You must include this in all programs using the library, either directly or through some other header file, like this:
The name space of `KSBA' is
ksba_* for function names,
ksba* for data types and
KSBA_* for other symbols. In
addition the same name prefixes with one prepended underscore are
reserved for internal use and should never be used by an application.