Masking a boot sequence by providing a dummy processor is provided. One of the processors of a multiprocessor system is chosen to be a boot processor. The other processors of the multiprocessor system execute masking code that generates electromagnetic and/or thermal signatures that mask the electromagnetic and/or thermal signatures of the actual boot processor. The execution of the masking code on the non-boot processors preferably generates electromagnetic and/or thermal signatures that approximate the signatures of the actual boot code execution on the boot processor. One of the non-boot processors is selected to execute masking code that is different from the other masking code sequence to thereby generate an electromagnetic and/or thermal signature that appears to be unique from an external monitoring perspective.