processing orders for both physical and electronic keys electronically generating and distributing keys generating key material for FIREFLY (an NSA algorithm) performing seed conversion and rekey maintaining compromise recovery and management of FIREFLY material support for over-the-air rekeying (OTAR) The CF talks to other EKMS elements through a variety of media, communication devices, and networks, either through direct distance dialing using STU-III (data mode) or dedicated link access using KG-84 devices. During the transition to full electronic key, the 3.5-inch floppy disk and 9-track magnetic tape are also supported. A common user interface, the TCP/IP-based message service, is the primary method of communication with the CF. The message service permits EKMS elements to store EKMS messages that include electronic key for later retrieval by another EKMS element. Tier 1 Under CMCS, each service maintained a central office of record (COR) that performed basic key and COMSEC management functions, such as key ordering, distribution, inventory control, etc. Under EKMS, each service operates its own key management system using EKMS Tier 1 software that supports physical and electronic key distribution, traditional electronic key generation, management of material distribution, ordering, and other related accounting and COR functions. Common Tier 1 is based on the U.S. Navy's key distribution system (NKDS) software developed by the Naval Research Laboratory and further developed by SAIC in San Diego. Tier 2 EKMS Tier 2, the Local Management Device (LMD), is composed of a commercial off-the-shelf (COTS) personal computer (PC) running the Santa Cruz Operation's SCO UNIX operating system, and an NSA KOK-22A Key Processor (KP). The KP is a trusted component of EKMS. It performs cryptographic functions, including encryption and decryption functions for the account, as well as key generation, and electronic signature operations. The KP is capable of secure field generation of traditional keys. Locally generated keys can be employed in crypto-net communications, transmission security (TRANSEC) applications, point-to-point circuits, and virtually anywhere that paper-based keys were used. Electronic keys can be downloaded directly to a fill device, such as the KYK-13, KYX-15, or the more modern AN/CYZ-10 Data Transfer Device (DTD) for further transfer (or fill) into the end cryptographic unit. Tier 3 The lowest tier or layer of the EKMS architecture which includes the AN/CYZ-10 (Data Transfer Device (DTD)), the SKL (Simple Key Loader) AN/PYQ-10, and all other means used to fill keys to End Cryptographic Units (ECUs); hard copy material holdings only; and STU-III/STE