His classes at Northwestern were attended by cartoonist Chester Gould, who is said to have based the incorruptible, square-jawed Dick Tracy character on Keeler and his colleagues.
Ninety years after its invention, the polygraph still has not been accepted by the scientific, legal or political communities. It does not help that every now and again serious criminals trick the polygraph.
Ridgway had passed a lie detector test in , while another man - who turned out to be innocent - failed. It has been argued that psychopaths like Ridgway or serial killer Ted Bundy are able to trick the polygraph because they have lower anxiety levels than normal people but the research into this has had mixed results.
Polygraphy has no grounding in science because polygraph techniques in use today were developed by interrogators, not scientists, says George Maschke, a former US Army intelligence officer and co-founder of AntiPolygraph. Polygraphy has not advanced in the way a scientific field would, and that is because it's not a science, it's an interrogation technique.
It can be useful in getting confessions, but it is not reliable in and of itself. You don't have to be a trained spy or a sociopath. You just have to understand how to recognise the control questions and augment reactions to them with techniques such as biting the side of your tongue or solving a maths equation in your head," he says.
William F. Friedman [top] dominated U. National Security Agency. His friend Boris Hagelin [bottom], a brilliant Swedish inventor and entrepreneur, founded Crypto AG in in Zug, Switzerland, and built it into the world's largest cipher-machine company. TOP, U. Parts of this story emerged in leaks by CAG employees before and, especially, in a subsequent investigation by the Washington Post and a pair of European broadcasters, Zweites Deutsches Fernsehen , in Germany, and Schweizer Radio und Fernsehen , in Switzerland.
The Post 's article , published on 11 February , touched off firestorms in the fields of cryptology, information security, and intelligence. The revelations badly damaged the Swiss reputation for discretion and dependability. They triggered civil and criminal litigation and an investigation by the Swiss government and, just this past May, led to the resignation of the Swiss intelligence chief Jean-Philippe Gaudin, who had fallen out with the defense minister over how the revelations had been handled.
In fact, there's an interesting parallel to our modern era, in which backdoors are increasingly common and the FBI and other U. Even before these revelations, I was deeply fascinated by the HX, the last of the great rotor machines.
This particular unit, different from the one I had seen a decade before, had been untouched since I immediately began to plan the restoration of this historically resonant machine. People have been using codes and ciphers to protect sensitive information for a couple of thousand years. The first ciphers were based on hand calculations and tables. In , a mechanical device that became known as the Alberti cipher wheel was introduced. Then, just after World War I, an enormous breakthrough occurred, one of the greatest in cryptographic history : Edward Hebern in the United States, Hugo Koch in the Netherlands, and Arthur Scherbius in Germany, within months of one another, patented electromechanical machines that used rotors to encipher messages.
Thus began the era of the rotor machine. Scherbius's machine became the basis for the famous Enigma used by the German military from the s until the end of WW II. To understand how a rotor machine works, first recall the basic goal of cryptography: substituting each of the letters in a message, called plaintext, with other letters in order to produce an unreadable message, called ciphertext.
It's not enough to make the same substitution every time—replacing every F with a Q , for example, and every K with an H. Such a monoalphabetic cipher would be easily solved. A simple cipher machine, such as the Enigma machine used by the German Army during World War II, has three rotors, each with 26 positions. Each position corresponds to a letter of the alphabet. Electric current enters at a position on one side of the first rotor, corresponding to a letter, say T.
The current travels through two other rotors in the same way and then, finally, exits the third rotor at a position that corresponds to a different letter, say R. So in this case, the letter T has been encrypted as R. The next time the operator strikes a key, one or more of the rotors move with respect to one another, so the next letter is encrypted with an entirely different set of permutations.
In the Enigma cipher machines [below] a plugboard added a fixed scramble to the encipherment of the rotors, swapping up to 13 letter pairs. A rotor machine gets around that problem using—you guessed it—rotors. Start with a round disk that's roughly the diameter of a hockey puck, but thinner.
On both sides of the disk, spaced evenly around the edge, are 26 metal contacts, each corresponding to a letter of the English alphabet. Inside the disk are wires connecting a contact on one side of the disk to a different one on the other side. The disk is connected electrically to a typewriter-like keyboard.
When a user hits a key on the keyboard, say W , electric current flows to the W position on one side of the rotor. The current goes through a wire in the rotor and comes out at another position, say L. However, after that keystroke, the rotor rotates one or more positions.
So the next time the user hits the W key, the letter will be encrypted not as L but rather as some other letter. Though more challenging than simple substitution, such a basic, one-rotor machine would be child's play for a trained cryptanalyst to solve.
So rotor machines used multiple rotors. Versions of the Enigma, for example, had either three rotors or four. In operation, each rotor moved at varying intervals with respect to the others: A keystroke could move one rotor or two, or all of them. Operators further complicated the encryption scheme by choosing from an assortment of rotors, each wired differently, to insert in their machine.
Military Enigma machines also had a plugboard, which swapped specific pairs of letters both at the keyboard input and at the output lamps. The rotor-machine era finally ended around , with the advent of electronic and software encryption, although a Soviet rotor machine called Fialka was deployed well into the s.
The HX pushed the envelope of cryptography. For starters it has a bank of nine removable rotors. The unit I acquired has a cast-aluminum base, a power supply, a motor drive, a mechanical keyboard, and a paper-tape printer designed to display both the input text and either the enciphered or deciphered text. In encryption mode, the operator types in the plaintext, and the encrypted message is printed out on the paper tape.
Each plaintext letter typed into the keyboard is scrambled according to the many permutations of the rotor bank and modificator to yield the ciphertext letter. In decryption mode, the process is reversed. The user types in the encrypted message, and both the original and decrypted message are printed, character by character and side by side, on the paper tape. While encrypting or decrypting a message, the HX prints both the original and the encrypted message on paper tape.
The blue wheels are made of an absorbent foam that soaks up ink and applies it to the embossed print wheels. Beneath the nine rotors on the HX are nine keys that unlock each rotor to set the initial rotor position before starting a message. That initial position is an important component of the cryptographic key. To begin encrypting a message, you select nine rotors out of 12 and set up the rotor pins that determine the stepping motion of the rotors relative to one another.
Then you place the rotors in the machine in a specific order from right to left, and set each rotor in a specific starting position. Finally, you set each of the 41 modificator switches to a previously determined position.
To decrypt the message, those same rotors and settings, along with those of the modificator, must be re-created in the receiver's identical machine.
All of these positions, wirings, and settings of the rotors and of the modificator are collectively known as the key. The HX includes, in addition to the hand crank, a nickel-cadmium battery to run the rotor circuit and printer if no mains power is available.
A volt DC linear power supply runs the motor and printer and charges the battery. The precision volt motor runs continuously, driving the rotors and the printer shaft through a reduction gear and a clutch. Pressing a key on the keyboard releases a mechanical stop, so the gear drive propels the machine through a single cycle, turning the shaft, which advances the rotors and prints a character. The printer has two embossed alphabet wheels, which rotate on each keystroke and are stopped at the desired letter by four solenoids and ratchet mechanisms.
Fed by output from the rotor bank and keyboard, mechanical shaft encoders sense the position of the alphabet printing wheels and stop the rotation at the required letter.
Each alphabet wheel has its own encoder. One set prints the input on the left half of the paper tape; the other prints the output on the right side of the tape.
After an alphabet wheel is stopped, a cam releases a print hammer, which strikes the paper tape against the embossed letter. At the last step the motor advances the paper tape, completing the cycle, and the machine is ready for the next letter. As I began restoring the HX, I quickly realized the scope of the challenge.
The plastic gears and rubber parts had deteriorated, to the point where the mechanical stress of motor-driven operation could easily destroy them. Replacement parts don't exist, so I had to build such parts myself. After cleaning and lubricating the machine, I struck a few keys on the keyboard. I was delighted to see that all nine cipher rotors turned and the machine printed a few characters on the paper tape. But the printout was intermittently blank and distorted.
I replaced the corroded nickel-cadmium battery and rewired the power transformer, then gradually applied AC power. To my amazement, the motor, rotors, and the printer worked for a few keystrokes. But suddenly there was a crash of gnashing gears, and broken plastic bits flew out of the machine. Printing stopped altogether, and my heartbeat nearly did too.
I decided to disassemble the HX into modules: The rotor bank lifted off, then the printer. The base contains the keyboard, power supply, and controls. These snubbers had disintegrated.
Also, the foam disks that ink the alphabet wheels were decomposing, and gooey bits were clogging the alphabet wheels. I made some happy, serendipitous finds. To rebuild the broken printer parts, I needed a dense rubber tube. I discovered that a widely available neoprene vacuum hose worked perfectly. Using a drill press and a steel rod as a mandrel, I cut the hose into precise, millimeter sections.
But the space deep within the printer, where the plastic snubbers are supposed to be, was blocked by many shafts and levers, which seemed too risky to remove and replace.
So I used right-angle long-nosed pliers and dental tools to maneuver the new snubbers under the mechanism. After hours of deft surgery, I managed to install the snubbers. The HX has nine rotors and also uses a technique called reinjection. Or anger over being asked an intrusive question? Could it be a reaction to an unrelated memory that a question has evoked?
Yet the laboratory conditions in which their studies were performed were very different from real life. This was intended to convince the subject, before the main part of the examination began, that the polygraph was infallible.
This response could be generated in a number of ways. The subject might be asked to select a playing card, examine it, and answer no to everything the operator asked about it. Is it a face card? To make sure the test worked, the operator used a marked deck. During the s and s law-enforcement agencies across the country began to adopt the polygraph for criminal cases.
Edgar Hoover, on lie detectors. The military services tested the device for use in intelligence work during World War II. Researchers continued to try to refine and improve the lie detector, focusing in particular on the interrogation format. A lawyer named John E. The aim was to distinguish the reaction to lying from simple nervousness.
Skill at evaluating information beyond the actual tracings is thought to explain why on-the-scene testers are usually better at detecting deception than polygraph experts who review charts after the fact. Yet this difference belies the claims that polygraphy is an objective scientific technique; you might just as well ask the police officers who interviewed a suspect for their opinion.
During the s Cleve Backster, who instituted the polygraph program at the CIA, tried to minimize operator bias by standardizing and quantifying the reading of lie-detector charts. He also refined even further the methods for conducting a polygraph interview.
At the same time, David T. Was it red … blue … brown? A guilty party, asked to repeat each word, would presumably show a physiological reaction to the crime element, while an innocent person would not. No complicated interrogation technique or intrusive questions were needed.
However, this technique is limited to interrogations that center on a specific incident, and the polygraph operator must be aware of details about the crime that are not widely known and that the criminal has noticed and remembered. By use of the lie detector in the United States had increased tenfold in a single decade. The polygraph had found a new role: employee screening. Leonarde Keeler had envisioned a role for the device in private business as early as , but only after World War II did corporations embrace the technology.
Companies used lie detectors as an economical way to select prospective employees and investigate internal theft, with periodic tests acting as a deterrent to malfeasance. Polygraph schools sprang up around the country, and some corporations kept polygraph specialists on salary.
Lie detecting became something of a craze, with one Dallas firm conducting 42, polygraph tests on its applicants in alone. The government turned to the polygraph to test potential employees in intelligence and defense posts, asking about everything from Communist sympathies to unconventional sexual practices.
Law-enforcement agencies continued to use the lie detector too, but by the s employee screening had surpassed criminal investigation as the primary use of the technology. To the extent that polygraph screening did work, it did so in part because of the intimidation factor: It encouraged employees or candidates to reveal information that they might otherwise have hidden.
During a lie-detector test the subject is given a chance, before or after the exam begins, to admit any wrongdoing or suspicious activity that might influence the results. After the machine is switched off, the subject can be asked to explain indications of deception on the chart. Eager to clear themselves, subjects may admit to peccadilloes or even major crimes. Critics believe that such interrogations amount to invasions of privacy. In another congressional committee recommended that government agencies stop using lie detectors altogether.
Massachusetts passed the first ban on compulsory polygraph tests for employment in A few other states followed suit, but in a federal law, the Employee Polygraph Protection Act, made it illegal for an employer to require a lie-detector test for job applicants or employees. Firms involved in certain industries, such as security, were exempt, though, as were all lawenforcement and other government agencies.
The technology of lie detection has remained remarkably stable since Keeler established the basics in the early s. Over the years just a few inventors have introduced changes. One added a second respiration sensor so that thoracic and abdominal breathing could be tracked separately. Another introduced an amplifier to let the blood-pressure cuff work at a lower pressure. Many modern machines are fully electronic, equipped with pressure sensors instead of mechanical tambours to convert data to pen movement.
Lie detectors began to be connected to computers during the s, with digital readouts replacing the tracings of ink on paper.
0コメント