The following describes an apparatus for and method of providing a secure method of downloading a program into a processor (101) from a device (103) external to the processor (101). The program may be encrypted (207) prior to its entry into the external device (103). The program may also have authentication information added (203 and 207) to it. Authentication information may be provided on an unencrypted and/or an encrypted program. The processor (101) decrypts (307) and/or successfully authenticates (311) the program before allowing the program to be executed by the processor (101).