Information systems security equipment modification

Modification of any fielded hardware, firmware, software, or portion thereof, under NSA configuration control. There are three classes of modifications: mandatory (to include human safety); optional/special mission modifications; and repair actions. These classes apply to elements, subassemblies, equipment, systems, and software packages performing functions such as key generation, key distribution, message encryption, decryption, authentication, or those mechanisms necessary to satisfy security policy, labeling, identification, or accountability.