ssf2/ssf_symencr_alg is a SAP Parameter attribute which is used to control Symmetric Encryption Algorithm for 2nd SSF toolkit 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 .
Name of the symmetrical encryption procedure that is used as the
standard value for the security toolkit specified with ssf2/ssfapi_lib.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.