ssf2/ssfapi_lib is a SAP Parameter attribute which is used to control complete path and filename for 2nd SSF API external library information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
The name of the SSF-API shared library that must be delivered by the
manufacturer of the security product is configured with this parameter.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.