Family of full duplex key generators, providing cryptographic security for all classifications of digital data traffic, encrypting and decrypting data at rates from 9.6 Kbps to 13 Mbps. The KG-94 is a non-ruggedized, rack mounted equipment, provides digital trunk encryption in association with the AN/TYC-39, AN/TTC-42, and the digital group multiplexer (DGM)equipment, as well as in non-TRI-TAC applications. The KG-94 can replace the KG-81 in applications requiring up to 13 Mbps. The KG-94 can be installed in 19" racks using either the HNF-81 or the HGF-94. The KG-94/194/94A/194A are all cryptographically compatible with each other, as well as with the KG-81 and KG-95 within their respective data rates when used in the traditional key mode.