NetSim has the following inbuilt encryption algorithms:
- AES
- DES
- TEA
Since the NetSim source codes are available users can implement their in your own by getting the code from some standard source like say Crypto++.
Using the Wireshark interface users can compare the differences in the payload when running with and without encryption
Turning to performance, NetSim is a network simulator and models parameters that affect network delays. It does not model "compute" delays and assumes infinite compute capability. Hence in NetSim, there will be no difference in the delay with/without the cryptographic algorithms.