On all non-Windows platforms, the agent code used to encrypt and decrypt the shared secret uses a key that is derived from a hard coded value combined with the results of calling gethostid() on the platform in question. gethostid() is a standard C Library function that returns a 32-bit long value.
Different UNIX system implements this function differently. For e.g Linux, AIX and solaris , the system implementation for the gethostid() C library function is not the same.
As such, SiteMinder web agent might not be able to decrypt the shared secret generated in one UNIX system when moved to other system.
Not only that, if the host ID of the same system changes (due to change in IP, hostname, mac address etc ) , the webagent will not be able to decrypt the shared secret which was originally generated on the same system, in which case you need to re-register the trusted host.