Principles of Clandestine Communications
Face-to-face meetings, conducted secretly between operational personnel, are known as clandestine meetings. Such meetings are employed frequently in the field; chiefly with regard to management and administrative functions. In general, the advantages of clandestine meetings are 1) they save time, 2) they are used as a countermeasure against some forms of eavesdropping, 3) they offer a measure of certainty, and 4) they provide a means of exercising control. The stress and delicacy of secret work make human contact between an agent and his handler imperative, if an operation or organization is to survive and function effectively. The disadvantages of clandestine meetings reflect concerns of security. Participants may be under visual surveillance and the link between them may be discovered by direct or indirect betrayal. Accidental observation is also a consideration, as are snap searches. In cases where something physical is being passed, apprehension of the participants will provide direct evidence of clandestine activity.
Clandestine meetings are, for our purposes, divided into four categories: 1) meetings between unacquainted operatives; 2) meetings between acquainted operatives; 3) meetings between operatives and outsiders; 4) silent meetings, or brush contacts.
Meetings between unacquainted operatives require secure prearranged identification signals and special briefing. The general description and distinguishing features of each operative must be established and according to operational necessity known to one or both. The security problems inherent in the meeting must be analyzed. There may be risks in permitting certain operatives the ability to extensively describe others they are to meet. There may be liabilities in denying this knowledge. The description must preclude the possibility of accidental recognition of legitimate parties who just happen to be at the meeting site.
One approach to the problem of providing descriptions is the use of artificial description points, innocuous in themselves, which offer operatives means of recognition. This technique is sometimes called "showing the flag." Examples, which should not be confused with safety signals, described below, include the time-worn flower in a buttonhole or uniquely folded newspaper, familiar enough to readers of fiction. Artificial points are often given in lieu of physical descriptions involving height, weight, color of hair and color of eyes. They must be obvious enough to spur recognition yet common enough not to attract unwarranted notice. These points may also be made to mesh with prearranged dialogue.
Unique objects, such as consecutively numbered currency or two halves of the same bank-note, were once used as means of identification and this practice was continued professionally as late as World War I. Experience shows, however, that this technique should not be employed due to obvious liability in case of search or arrest.
Once initial recognition is achieved, the operatives must approach one another. At this juncture identification is made and a method often employed is that of a prearranged dialogue. This is sometimes known as use of paroles, or "secret conversation." For example: assume that the artificial descriptive point is a volume of Bronte. One operative offers, "I have never read Bronte." The other replies, "Do you mean Charlotte or Emily?" This is the first exchange. First exchanges are usually followed for safety's sake by a second exchange unrelated to the first. Again, by way of example: "I did not know there was a difference; as for me I am a gardener." The reply, "It is difficult to keep a garden in this climate." Such harmless dialogue must be structured to prevent accidental conversations with legitimate characters and must leave no question marks.
Meetings between acquainted operatives obviously do not require prearranged identification signals. In every other respect they do not and should not materially differ from other types.
Meetings between operatives and outsiders are in practice avoided but sometimes become necessary. In case where obvious risks are weighed and found to be tolerable, such meetings will be attempted subject to extensive security precautions. A classic example is the stranger who approaches a member of the Resistance, asking to join. Is he sincere, or an agent provocateur? In practice, if subsequent meetings are decided upon these will be handled by the operative first approached. The ruling assumption in such cases is that if the stranger is in fact an agent provocateur then the operative first approached is already "blown."
The manner by which federal agencies approach underground operatives merits further attention, to serve the interests of those readers who are faced with the task of identifying individuals who have been introduced into their groups. Recent federal instructional material covering this topic reads:
"...if the objective is a group of people, the agent will have to determine how he can join them. This can be done with the assistance of an informant who is in the group or, if it is a large group with formalized membership such as a club or "wing" organization, the direct approach of applying for membership may suffice. "...if the objective is to investigate a particular violation occurring at a specific location or to acquire general intelligence information, the approach could be accomplished merely by frequenting the area and establishing the assumed role."
(U.S. Department of Treasury, Law Enforcement School)
The above, while suitable for investigations of limited scope, does not acknowledge all-important questions of resistance countermeasures. Recruits must not be fully accepted until their past and present records of family life, jobs, political activities , and close associates have been investigated and found satisfactory. The usual practice is to restrict the recruit's contact to one member of the organization and to places other than the organization's regular meeting place.
Countermeasures include 1) loyalty tests, in which potential group members are subject to mock capture and interrogation, 2) a sudden summons to meet with security personnel under ominous circumstances designed to reveal signs of nervousness, 3) "leaks" purporting to inform the recruit that he has been blown and is marked for execution, and 4) a particularly effective technique involving change of meeting places. In the latter instance, potential members are kept unwitting of a change in site for a clandestine meeting at which they are expected to attend. Countersurveillants are posted to discover if the recruit is followed, or if surveillance personnel are in place at the site prior to his arrival. Assuming the recruit passes this test, he is approached and told that the meeting is off, or alternately, informed of the new meeting site.
Silent meetings, normally called brush contacts, are arguably not meetings at all. Orthodox silent meetings are conducted according to the rules of clandestine meeting practice and are normally used solely to pass something physical. Examples are exchanges of identical briefcases in a crowded airport, or the exchange of folded newspapers during a momentary pause on a park bench.
Clandestine meetings are further categorized in terms of their frequency. There are 1) regular meetings, 2) special meetings, and 3) control meetings.
Regular meetings take place according to a prearranged schedule and frequently involve the same site or sites. Such meetings will also be supported by "fall-backs," or alternative meeting times and sites, in case the regular meeting is missed for any reason.
Special meetings take place in response to special signals or requests, typically when the matter is of some urgency. Such meetings may or may not be supported by fall-backs.
Control meetings are functionally a combination of both regular and special meetings and are used in instances where a communication link has been broken or lost. In such cases, the operative must come to a prearranged site at a prearranged time to re-establish contact. Another sort of control meeting involves the use of "places of conspiracy." Places of conspiracy are utilized in emergency circumstances when an operative has been isolated through the capture or compromise of his immediate superior. In this case, the operative knows to visit a predetermined site at a particular time of day, showing certain recognition signals. A representative of the clandestine group takes not of the time and recognition signals, and if these are correct makes the approach. Because of the representative's vulnerable position as a contact for persons in danger, he is limited to this one duty and knows little about other aspects of the organization.
Meetings are held in the open, in public places or conveyances, under safe circumstances (safe-houses), and at a variety of other sites. Meeting sites should be selected on the basis of the ease with which countersurveillance may be practiced. They must be manageable. Deserted areas, for example, are ideal from a countersurveillance point of view, but assuming hostile surveillance the appearance of one operative in proximity to another in such an area may be cause for contamination. Granting this, more public places, such as parks, museums, parking lots, and a host of other locations are often used. Such places, unless selected with considerable care, can be unmanageable due to the volume of foot traffic and surrounding vantage points.
A worthwhile practice is the selection of pre-surveyed sites where ordinary traffic and activity have been observed over a long period of time. Some practitioners have selected convoy operators (countersurveillants) on the basis of their familiarity with the meeting site, acting on the principle that the convoy's job will be easier if he knows the area's normal routine.
Sites selected must actually exist, and must be accessible to both parties at the time set for the meeting. If audio surveillance is a factor the site should present participants with a measure of safety. Obviously the site and the cover must be closely intertwined. An example of this is use of a doctor's or dentist's office, or a motion picture theater. There must be plausible cover for every meeting and each operative must be fully aware of the details of this cover.
In the case of special meetings, requests are necessary. These are accomplished in any one of several ways. Distinctive arrangements of objects, chalk marks, and classified advertisements have all been used to signal requests. A common method is the use of "wrong numbers" in telephonic communication. The requester dials, and when the line is answered, asks for "Joe," or someone else who is not at that number. This is the signal that a meeting is being requested. Upon learning that, "There's nobody by that name here," the requester asks, "Is this 555-1613?" The number is a code which gives the date, time, and place. (In our example, 5 could refer to a place, 16 could refer to a day, and 13 could refer to 1300 hours). Following this the requester is informed he has reached a wrong number and rings off.
If an operative discovers or suspects he is being followed to a meeting site it becomes incumbent upon him to inform his contact of impending danger. To provide for this contingency safety signals evolved. Used in addition to recognition signals, safety signals silently advise meeting participants 1) it is it safe to approach for the secret conversation, 2) if surveillance is suspected, and 3) if a fall-back meeting is feasible.
To again follow our example of an operative with a volume of Bronte, let us assume the meeting is to take place in a public library. The operative is seated, and apart from serving as a recognition point, his book also becomes a safety signal. If the book is placed on his right it is safe to approach; on his left, there is danger. If the book lies open and face down this informs that a fall-back will take place.
Vigorous, often elaborate and time consuming countersurveillance is practiced by both participants on the way to and from meeting sites. Convoys or countersurveillants are often used to guard participants going to and from meetings. Guards are also used in the vicinity of the site itself. Another technique frequently employed is the staggered arrival. Participants arrive separately at intervals, sometimes as long as thirty minutes or more, taking special effort to observe signs of hostile activity.
Drops, known variously as "letter drops" are defined as a person, place, conveyance, or object used to transmit messages, money, or equipment in secrecy between operational personnel. Drops are used in both internal and external clandestine communications.
Drops are used in preference to clandestine meetings. In general, the advantages of drops are 1) greater secrecy for communications, and 2) greater security for personnel. Use of drops can reduce the number of clandestine meetings and offer considerably more flexibility in time. There is no direct contact between parties, and assuming the drop remains inviolate, only one operative is exposed at any given moment. Drops may be established in depth to facilitate increased isolation of either sender or receiver, or used to create a reserve of operational necessities. They are also adaptable for use by different types of personnel, such as low-level utility operatives (cut-outs) or those with poor language skills.
The principle disadvantage of drops is uncertainty. While loaded, materials in drops are outside the operative's immediate control. Drops are also liable to accidental or deliberate discovery with subsequent adverse manipulation, and the ravages of fire, flood, or wild animals. Extensive use of drops may also have a negative effect on management. Fewer meetings decrease the opportunities to train and evaluate agents.
Drops are used for both long and short term storage. Long term storage is calculated in terms of days or weeks; short term in hours. When employed for the purpose of communication, drops may hold original documents or full sized copies; or , alternately, reduced reproductions on film. Film is usually undeveloped, and placed in "trapped" containers. Documents may be in cipher or clear text. As stated above, drops are also used to transmit money or supplies. Examples of the latter include weapons, medical equipment, or other technical apparatus. Drops are of two principle types: 1) "live" drops, and 2) dead drops.
Live drops may be witting or unwitting, id est, they may or may not operate with knowledge of the clandestine purpose. Live drops are not encumbered by any organizational forms and do not require a special cover or camouflage. They are located in stores, restaurants, offices, or small shops such as those maintained by news stands or tobacconists. These locations provide ease of access for couriers and employ a high degree of normal, transient foot traffic.
Another form of live drop is the so-called underground mail station. Such drops may be located in safe-houses especially developed for the purpose with elaborate concealment chambers. As materials are received, housekeepers send coded signals or messages to the next link of the courier line, advising that service is necessary.
Dead drops are categorized variously by type or location. In the former category we find 1) stationary drops, and 2) portable drops. In the later category we find 1) urban drops, and 2) rural drops. Both categories admit of the mobile, or "roving" drop.
Stationary dead drops are selected or prepared in lamp-posts, fences, behind mirrors in washrooms, and in a host of other places such as crevices in rocks of clefts in trees. Portable dead drops, also known as "concealment devices," are discarded or specially constructed objects that contain messages, documents or equipment to be passed. Early U.S. practitioners responsible for devising concealment devices soon discovered that the cardinal principle in producing concealment devices was that the subject of disguise be neither edible nor burnable. In such cases it is liable to be used by some casual passer-by. Magnetic key-boxes, used to hide a duplicate key beneath an automobile bumper, are often used as portable drops. Mobile drops are located in conveyances, popularly the lavatories on trains, buses, or aircraft.
Urban drops are those located in public or otherwise freely accessible places and are typically used for extremely short term transmittals. Rural drops, as the term implies, are located in rustic or rural places. Rural drops are used for either short or long term transmittals.
Advisory signals and indicators are used to express 1) what particular drop is to be serviced, 2) safety or danger, 3) a drop is loaded, and 4) a drop is unloaded.
In common practice, operatives assigned to service drops will do so in response to signaled requests. This signal will usually indicate which drop is loaded, and be supported by a safety/danger signal. We note parenthetically that absence of a safety signal is regarded as a danger signal. Proceeding to the area of the drop, the operative will practice diligent countersurveillance. If the operative is confident of security the drop will be quickly unloaded. He will then make a signal to this effect supported by another safety/danger signal. Safety/danger signals are always made on return journeys, after countersurveillance has been practiced going to and coming from the drop site.
Generally, signals can be divided into five categories, as follows:
1. Graphic. Chalk marks expressing numbers, letters, or designs; notices appearing in the classified section of a newspaper, postcards, or other forms of correspondence.
2. Object. Any small object, such as a flower-pot, or arrangement of an object, such as a window shade. The object may be used independently or tangentially; that is, the object and its position may both hold significance.
3. Light. Ordinary flashlights, automobile headlights, or infrared light.
4. Sound. Radio transmissions, telephone calls, distinctive rings on door buzzers.
5. Personal. Articles of clothing, or objects carried.
Certain signals or combinations may be used solely in conjunction with specific activities. Graphic and object signals, for example, may be used with dead drops. Light and sound signals with some other activity.