Over-the-air rekeying (OTAR) refers to transmitting or updating encryption keys (rekeying) in 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, the technology is also employed via wire, cable, or optical fiber. As a "paperless encryption key system" OTAR was originally adopted specifically in support of high speed data communications because previously known "paperless key" systems such as supported by Diffie-Hellman key exchange, or Firefly key exchange technology (as used in the now obsolete STU-III "scrambled" telephone) were not capable of handling the high speed transmission volumes required by normal governmental/military communications traffic. Now also adopted for civilian and commercial secure voice use, especially by emergency first responders, OTAR has become not only a security technology, but a preferred basis of communications security doctrine world-wide. The term "OTAR" is now basic to the lexicon of communications security. History OTAR was operationally introduced to the US Department of Defense via the Navy beginning in 1988. 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 security potential of OTAR. In order to exploit the advantages of this technology, he conceived and initiated its first large scale practical application and deployment. Due to the efficiency and vast cost savings inherent to OTAR, Commander Winters' methods were quickly adopted and spread Navy-wide, following which Vice Admiral J.O Tuttle, Commander of the Navy Telecommunications Command, the Navy "J6", shortly influenced the Joint Chiefs of Staff to bring all the other military services into compliance. In due course, OTAR shortly became the NATO standard. This coincided with the 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 communications circuits. Adoption of OTAR reduces requirements both for the distribution of physical keying material and the physical process of loading cryptographic devices with key tapes. Accordingly, OTAR eliminates the need for individual stations to be involved with physical key changeovers. Instead, electronically transmitted keys would normally come from a network control station