a NOVIRUS, SYSTEM MANAGEMENT, Virus protection, self-checking images, calculating CRC32 at run-time   L Virus protection is not a hot item for VMS system managers, but I am workingF in a GLP (Good Laboratory Practice) environment and was bothered with N questions about VMS virus protection several times. To be able to reply to theJ customers and regulatory inspectors I added a self-check mechanism to our  self-developed images.  M This self-check mechanism calculates a 32 bits Cyclic Redundancy Check of the E image and compares it with a pre-defined CRC in an external key file. G The routines are written in C and can be included in applications where  security demands are high.  K Ofcourse, no real virus protection is given, but the mechanism serves as an K early warning system for future virus attacks, media corruption, hacks etc. N You now can prove that a program is in a well-defined state and should execute  just like the validated version.  F Read [.SRC]README.TXT for more details. See CALCCRC and DEMOCRC for a  demonstration.  O CALCCRC is an utility to calculate the CRC checksum of an arbitrary file and is I used to calculate the CRC value for inclusion in the external key files.  8 CALCCRC can also be used to detect changes on datafiles.  G DEMOCRC is a self-checking image. If there is a difference detected, an / operator request is made and the program halts.   