VOLUME I Multinational Maritime Tactical Instructions and Procedures

(7) Attention to equipment maintenance to produce minimal internal noise and nullify the possibility
of radiation of encrypted or unencrypted traffic from the superstructure of the transmitting unit or
other improper antenna.
b. COMSEC procedures form an integral part of electronic protective measures (EPM).
4132 AUTHENTICATION
a. Principles. Authentication is used as a measure of protection against imitative deception on
communication circuits. Current authentication procedures are based upon the following principles:
(1) Authentication should not be used unless warranted by the degree of risk that imitative deception
may be attempted by the enemy.
(2) When used, the amount of circuit time devoted to the procedure should be the minimum consistent
with the achievement of an acceptable level of protection against the unit employing imitative
deception.
b. Risk of Imitative Deception. Risk exists on all types of uncovered circuits, and tactical voice
circuits are an obvious potential target. Morse circuits, which may replace certain RATT channels that
have been subjected to heavy ECM, may be vulnerable to imitative deception. The risk of imitative
deception will depend upon what the enemy has to gain from its employment in any tactical situation and
governs the establishment of the authentication policy (see Article 4133).
NOT RELEASABLE
c. Authentication Procedures. Present authentication rules call for the Challenge and Reply
mode whenever possible, because it is significantly more secure than the Transmission mode. It does not
follow that the lower level of security attainable through the latter is not an acceptable compromise
between security and circuit occupancy, when it is backed up by Challenge and Reply, if the credibility of a
given message is in doubt. This is amplified in Table 4-1, but it should be noted that it is relatively easy for
an experienced unit employing imitative deception to obtain an indate transmission authentication from
one circuit and to use it on another; and it is, therefore, a cardinal rule that a receiving station always
initiates a Challenge and Reply whenever the transmitting station has not been identified as friendly.
4133 AUTHENTICATION POLICIES
a. Definitions.
(1) Policy ALFA — Enemy forces are likely to use imitative deception; or the use of imitative deception
has been confirmed and a resulting change in policy ordered by the OTC.
(2) Policy BRAVO — Imitative deception is unlikely to be used by the enemy.
b. Use of Authentication Policies.
MTP 1(D), Vol. I
(1) If the tactical situation is in favor of the enemy trying to conduct imitative deception, the full degree
of authentication is to be implemented as in Policy ALFA (Occasions 1 to 14 in Table 4-1). This
also applies when imitative deception has already been confirmed. To guard against the situation in
which the marker attempts imitative deception simply to test the forces reaction (and the OTC does not
wish to reveal the practical effects of Policy ALFA), Policy BRAVO may be ordered by the OTC.
(2) In Policy BRAVO, authentication is used infrequently (Occasions 1 to 8 in Table 4-1). The initial
stage of a marking situation is typical of one in which Policy BRAVO would be appropriate: the
marker is intent on monitoring rather than interfering with communications. The only benefit to the
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