A script in the C language cannot run javascript code (or java, for that matter).
Therefore, you will have to try to re-implement the encryptSecurityfunction() in C.
That's the bad news.
The good news is that this may not be very difficult. The call to "getSessionRandom()" suggests that all you really need to do is generate a random string of alphanumerical characters. Which is where y-lib comes in:
https://github.com/randakar/y-lib/blob/master/y_loadrunner_utils.c#L412
In principle this should be a matter of: Add y-lib to your script (with the "add files to script" function and a "#include 'y-lib.c'" statement at the top of vuser_init() ), and then call y_random_string_buffer_core():
https://github.com/randakar/y-lib/blob/master/y_loadrunner_utils.c#L389
y_random_string_buffer_core("parametername", 8, 12, 0, 0, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");
That will create a random alphanumerical string at least 8 and no more than 12 characters long, using a min and max word length of 0 characters (no words, in other words).
( I should probably create a y_random_string_buffer_alphanum(), but heh, this code is at least 5 years old by now ..) like this: https://github.com/randakar/y-lib/blob/master/y_loadrunner_utils.c#L389 )
