Over the Air Rekeying

Over the Air Rekeying (OTAR) is the common name for the method of transmitting, or remotely transferring,changing,or updating, data signal encryption "code" keys in telecommunication, control, navigation, or other secure information systems by conveying the keys via encrypted electronic communication channels (“over the air”). It is also referred to as Over-the-Air Transfer (OTAT), or Over-the-Air-Distribution (OTAD)depending on the specific type, use, and transmission means of the key being changed. Although the acronym refers specifically to radio transmission means, the technology is also employed via land line and cable.

OTAR was operationally introduced to the US Department of Defense via the Navy in 1988 through 1993. Lieutenant Commander David Winters, an American naval officer in London and "code master" during the final years of the Cold War, was first to recognize the necessity and revolutionary security potential of OTAR and personally oversaw development and deployment of the innovative procedures required.

Commander Winters' methods were quickly adopted and spread Navy wide, in response to which Vice Admiral J.O Tuttle,the Navy "J6", shortly influenced the Joint Chiefs of Staff to bring all the other military services into compliance.

This coincided with introduction of newer NSA cryptographic systems that use a 128-bit electronic key, such as the ANDVT, KY-58, KG-84A/C, and KY-75, capable of obtaining new or updated keys via the circuit they protect or other secure scommunications circuits. Adoption of OTAR drastically reduces requirements both for distribution of physical keying material and the physical process of loading cryptographic devices with key tapes.

OTAR essentially eliminates need for individual stations to be involved with tangible physical code key changeovers on a day-to-day updates. Instead, electronically transmitted keys would normally come from a Network Control Station (NCS). The OTAT feature permits key to be extracted from an OTAT-capable cryptographic system using a fill device, such as the KYK-13 or KYX-15/KYX-15A and then loaded ("squirted") into another cryptographic system as needed.

Alternatively, encryption systems may also be configured to automatically receive and update code keys with virtually no human intervention, as is the case for GPS (Geo-Positioning-System) navigation satellite signals.

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