"dm" == Dan Marner <dmarner@mis.nu.edu> writes: dm> I would appreciate any pointers to documents, source code or dm> programs that deal with using cryptographic techniques to detect dm> or prevent modification of executable code. I am looking for dm> something that uses either a signature or a one-way hash to detect dm> modifications at run time. dm> Of particular interest is information on signing a file that dm> includes the signature as part of the file. Is this possible with dm> any of the common algorithms? Claris has or had some checks in their software to attempt to recognize that the application had been modified. I think this even detected a (previously unknown?) Macintosh virus. Regardless, this scheme seems rather susceptible to attack. More useful is something like tripwire--a regularly run program which keeps checksums of various files on disk; stores the checksums on apart from the data; and compares the previous checksum with the current checksum. michael