TRANSMISSION SECURITY

Transmission security results from measures designed to protect transmission from interception and exploitation by means other than cryptographic analysis. In the next paragraphs, we will discuss specific methods of transmission security.

COMMUNICATIONS SECURITY (COMSEC) EQUIPMENT

There are numerous types of cryptographic equipment used throughout the Navy. However, they all perform the same basic function-to encipher or decipher a communications signal.

During secure transmission, the cryptoequipment accepts a "plain text" teleprinter or data signal containing classified information from the classified (red) patch panel and adds a "key" (randomly chosen bits generated internally). This composite signal is relayed as an encrypted signal.

Following this encryption, the signal is fed to the unclassified (black) patch panel where it is patched directly to a converter. This converted audio signal is then routed to the transmitter for transmission.

Over-the-Air Rekey/Transfer (OTAR/OTAT)

Many of the new cryptosystems that use the 128-bit electronic key (ANDVT, KY-58, KG-84A/C, and KY-75) are now capable of obtaining new or updated key via the circuit they protect or other secure communications circuits. This process is known as over-the-air rekey (OTAR) or over-the-air transfer (OTAT). The use of OTAR or OTAT drastically reduces the distribution of physical keying material and the physical process of loading cryptoequipments with key tapes.

A station may have nothing to do with actual physical CRYPTO changeovers on a day-to-day basis.

All an operator would have to do is observe the alarm indications and ensure the alarm indicator returns to operate. The electronic key would normally come from the Net Control Station (NCS).

The added feature of OTAT is that the key can be extracted from an OTAT-capable cryptosystem using a KYK-13 or KYX-15/KYX-15A. The key is then loaded into another cyptosystem as needed. More detailed information on OTAR/OTAT is available in the Procedures Manual for Over-the-Air Transfer (OTAT) and Over-the-Air Rekey (OTAR) and Field Generation and Over-the-Air Distribution of Tactical Electronic Key, NAG-16C/TSEC.

Authentication

Authentication is a security measure designed to protect a communications or command system against fraudulent transmissions or simulation. Authenticating systems have instructions specifying the method of use and transmission procedures. By using an authenticating system properly, an operator can distinguish between genuine and fraudulent stations or transmissions. A station may include authentication in a transmitted message. This security measure is called transmission authentication. The types of authentication are:

l Challenge and Reply- This is a prearranged system whereby one station requests authentication of another station (the challenge). By a proper response, the latter station establishes its authenticity (the reply).

l Transmission Authentication- A station establishes the authenticity of its own transmission by either a message- or a self-authentication method. A message authentication is a procedure that a station uses to include an authenticator in the transmitted message. Self-authentication is a procedure that a station uses to establish its own authenticity, and the called station is not required to challenge the calling station.

The following examples are instances when authentication is mandatory:

l A station suspects intrusion on a circuit;

l A station is challenged or requested to authenticate;

l A station directs radio silence or requires another station to break an imposed radio silence; and

A station transmits operating instructions that affect communications, such as closing down a station, shifting frequency, or establishing a special circuit.

You can find further information on authentication in Communications Instructions-Security (U), ACP 122.

MEACONING, INTRUSION, JAMMING, AND INTERFERENCE (MIJI)

MIJI is a term used to describe four types of interference that you are likely to experience in a given situation.

Meaconing is the interception and rebroadcast of navigation signals. These signals are rebroadcast on the received frequency to confuse enemy navigation. Consequently, aircraft or ground stations are given inaccurate bearings. Meaconing is more of a concern to personnel in navigation ratings than to you as a Radioman. However, communications transmitters are often used to transmit navigation signals. Since communications personnel operate the transmitters, they must know how to deal with any communications problems resulting from meaconing.

Intrusion is defined as any attempt by an enemy to enter U.S. or allied communications systems and simulate our traffic to confuse and deceive. An example of intrusion is an unauthorized radio transmission by an unfriendly source pretending to be part of an air traffic control service and giving false instructions to a pilot.

Jamming is the deliberate radiation, reradiation, or reflection of electromagnetic signals to disrupt enemy use of electronic devices, equipment, or systems. In jamming operations, the signals produced are intended to obliterate or obscure the signals that an enemy is attempting to receive. Some common forms of jamming include:

l Several carriers adjusted to the victim frequency;

l Random noise amplitude-modulated carriers;

l Simulated traffic handling on the victim frequency;

l Random noise frequency-modulated carriers;

l Continuous-wave carrier (keyed or steady); and Several audio tones used in rapid sequence to amplitude modulate a carrier (called bagpipe from its characteristic sound).

Interference is normally a nondeliberate intrusion upon a circuit. It unintentionally degrades, disrupts, obstructs, or limits the effective performance of electronic or electrical equipment. Interference usually results from spurious emissions and responses or from intermodulation products. Sometimes, however, interference may be induced intentionally, as in some forms of electronic warfare. An example of interference is the interruption of military transmissions by a civilian radio broadcast.

The more effective methods of dealing with MIJI are contained in Fleet Communications, NTP 4, and in Reporting Meaconing, Intrusion, Jamming, and Inteference of Electromagnetic Systems, OPNAVINST 3430.18.

SUMMARY

In this chapter we introduced you to the basic concepts of communications security, described various cryptosystems, and familiarized you with the procedures and methods of transmission security.

As a Radioman, you have a two-fold job concerning security. The first, of course, is to properly perform your duties within general security guidelines. Security guidelines pertain to everyone in every official capacity. Second, you must also perform your duties in such a manner as to protect the integrity and overall value of secure communications.

Security violations result from bad personal habits, security indifference, occupational fatigue, or ignorance of established regulations. When security violations occur in installations located in foreign countries, the violations become more serious because of an activity's greater vulnerability to hostile exploitation. With respect to COMSEC, security violations could prove costly.

Security precautions mentioned in this chapter do not guarantee complete protection, nor do they attempt to meet every conceivable situation. Anyone who adopts a commonsense outlook can, however, solve most security problems and gain a knowledge of basic security regulations. For information on local security rules, study your command's security regulations.