The TIA-102 suite of documents describes the interfaces
\nassociated with a system for public safety land mobile radio
\ncommunications. These systems include subscriber units, base
\nstations and other fixed equipment. The term Subscriber Unit (SU)
\nincludes portable radios for handheld operation and mobile radios
\nfor vehicular operation. The base stations are used for
\ngeographically fixed installations. Other fixed equipment is used
\nfor wide area operation and console operator positions. Computer
\nequipment may be used to interface between each of these equipment
\nitems. A Common Air Interface (CAI), defined in [4], allows these
\nSUs to send and receive digital information over a radio
\nchannel.<\/p>\n
Many of the parts of a public safety Land Mobile Radio (LMR)
\ncommunications system use encryption to protect the information
\nwhich is sent through the system. The encryption algorithms require
\nkeys in order to protect the confidentiality of this information.
\nThe process by which these encryption keys are generated, stored,
\nprotected, transferred, loaded, used and destroyed is known as key
\nmanagement. These keys shall be protected from inadvertent
\ndisclosure and require updating or replacement in order to maintain
\nsystem security. Key distribution is often accomplished manually.
\nHowever, the most convenient way to distribute keys is to
\nelectronically send the keys from a key management facility to the
\ndestination equipment. This involves sending keys over the CAI and
\nthis procedure is referred to as Over-The-Air-Rekeying (OTAR). OTAR
\nis a method of encrypting and sending the encryption keys and other
\nrelated key management messages through the CAI in such a way that
\nthey are protected from inadvertent disclosure and, in some cases,
\nunauthorized modification.<\/p>\n
This document defines the Over-The-Air-Rekeying protocol,
\nmessages and procedures designed to promote interoperability
\nbetween various pieces of compliant radio equipment, regardless of
\nmanufacturer.<\/p>\n
The scope of this document is to address methods of OTAR and
\nassociated over the air key management functions in a multi-key
\nsystem. The primary objective of this document is to enable
\nsubscriber units and systems which conform to this document to be
\ninteroperable to the extent that keys can be passed via the CAI
\nbetween communicating units and encrypted communications can
\nresult. It is a further objective that conformance to this document
\nshall enable the interoperability of subscriber units and systems
\nprovided by different vendors, and operated by different agencies.
\nThis enables effective and reliable intra-agency and inter-agency
\nencrypted communications over the air. This is in conformance to
\nthe Statement of Requirements.<\/p>\n
Reference [5] defines a set of Algorithm ID values for
\nencryption algorithm interoperability such that encrypted messages,
\neither voice or data, can be encrypted and decrypted consistently
\nbetween endpoints. Interoperability is obtained by using the
\nstandardized encryption algorithms identified by those Algorithm
\nIDs. Conversely, the use of non-standardized or proprietary
\nAlgorithm IDs shall not be deemed as interoperable. Therefore, the
\nuse of the OTAR protocol to exchange keys for non-standardized or
\nproprietary Algorithm IDs shall preclude compliance with this
\ndocument for those messages carrying non-standardized or
\nproprietary Algorithm IDs.<\/p>\n
Figure 1 shows system elements which may include key management
\nfunctions (such as, portable or mobile radios, RF system gateways,
\nRF system controllers and consoles) that should be compatible with
\nthe core OTAR functions. OTAR functions include the encryption of
\nkeys to maintain their confidentiality and integrity during
\ntransmission. Encryption of keys while in storage and during
\ntransit helps maintain overall system security and confidentiality.
\nIntegrity of keys is required to prevent unauthorized insertion,
\ndeletion, or modification of keys.<\/p>\n
Keys are managed by a Key Manager function which is included in
\na Key Management Facility (KMF). This KMF system element maintains
\na link through a system's infrastructure to an Um air interface as
\ndefined in the General System Model. The KMF performs most of its
\nfunctions through the exchange of Key Management Messages (KMMs)
\nwith other system elements. Figure 1 shows a typical (example)
\nplacement of the KMF. The KMF functionality may also reside in
\nother system elements, such as, the console or a network management
\ncontroller. The protocols for these interfaces are not defined and
\nare beyond the scope of this document. Multiple KMFs may exist
\nwithin one RF sub-system concurrently.<\/p>\n
The Phase 2 TDMA standard defines a new air interface reference
\npoint designated as Um2. This interface conveys encrypted voice
\nmessages encrypted with the same algorithms and keys as the Um
\ninterface. The initial version of Um2 does not define packet data
\ntransmissions, so the OTAR functions are to be conveyed through the
\nUm interface to subscriber units.<\/p>\n","protected":false},"excerpt":{"rendered":"
Project 25 – Digital Radio Over-The-Air-Rekeying (OTAR) Messages and Procedures<\/b><\/p>\n\n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n TIA<\/b><\/a><\/td>\n 2014<\/td>\n 210<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":690349,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2646],"product_tag":[],"class_list":{"0":"post-690338","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-tia","8":"first","9":"instock","10":"sold-individually","11":"shipping-taxable","12":"purchasable","13":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/690338","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/690349"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=690338"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=690338"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=690338"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}