Request: tamper-proofing executables

[Dan Marner]

   I would appreciate any pointers to documents, source code or
programs that deal with using cryptographic techniques to detect
or prevent modification of executable code. I am looking for 
something that uses either a signature or a one-way hash to detect
modifications at run time. 
   Of particular interest is information on signing a file that
includes the signature as part of the file. Is this possible with
any of the common algorithms?
                                       Thanks! Dan
-- 
Dan Marner                             dmarner at mis.nu.edu
Network Weasel
National University                    "Not on MY network!"