Here is the MESP-100-2 two-channel exportable encrypt/decrypt module stack. It provides two channels of independently-controlled data encrypt/decrypt. The encryption modules are provided either as a dual-stack configuration like you see here or within a single stack configuration for single-channel operation. Each of the module stacks provides five connector interfaces. Plain-text interface for input/output data on J4. On J3 is the key fill interface - you have to load a key. J2 is the prime power interface - you need power to operate the unit. J1 is the plain-text output normally driven to a transmitter for transmission. The J5 is for the decryption process with the cypher text input. The plain-text interface on J4 also provides the decrypted plain-text output via TTL.