For those interested in TEMPEST, below is a draft paper written 5 years ago by Christopher Seline. Mr Seline's new E-mail address ends with "DOCKMASTER.NCSC.MIL", so any attempts to query him about TEMPEST are guaranteed to go unanswered. I hope he still feels the same about TEMPEST now that he has changed employers. Date: Fri, 19 Jan 90 19:13:44 -0500 From: cjs%cwru@cwjcc.ins.cwru.edu (Christopher J. Seline (CJS@CWRU.CWRU.EDU)) The following is a prepublication draft of an article on TEMPEST. I am posting it to this news group in the hope that it will: (1) stimulate discussion of this issue; (2) expose any technical errors in the document; (3) solicit new sources of information; (4) uncover anything I have forgotten to cover. I will be unable to monitor the discussions of the article. Therefore, PLEASE post your comments to the news group BUT SEND ME A COPY AT THE ADDRESS LISTED BELOW. I have gotten a number of mail messages about the format of this article. Some explanation is in order: The numbered paragraphs following "____________________" on each page are footnotes. I suggest printing out the document rather than reading it on your CRT. Thanks you in advance. Christopher Seline cjs@cwru.cwru.edu cjs@cwru.bitnet (c) 1990 Christopher J. Seline ============================================================================= <Start Print Job> <New Page> Eavesdropping On the Electromagnetic Emanations of Digital Equipment: The Laws of Canada, England and the United States This document is a rough draft. The Legal Sections are overviews. T h e y w i l l b e significantly expanded in the next version. We in this country, in this generation, are -- by destiny rather than choice -- the watchmen on the walls of world freedom.[1] -President John F. Kennedy _____________________ 1. Undelivered speech of President John F. Kennedy, Dallas Citizens Council (Nov. 22, 1963) 35-36. <New Page> In the novel 1984, George Orwell foretold a future where individuals had no expectation of privacy because the state monopolized the technology of spying. The government watched the actions of its subjects from birth to death. No one could protect himself because surveillance and counter- surveillance technology was controlled by the government. This note explores the legal status of a surveillance technology ruefully known as TEMPEST[2]. Using TEMPEST technology the information in any digital device may be intercepted and reconstructed into useful intelligence without the operative ever having to come near his target. The technology is especially useful in the interception of information stored in digital computers or displayed on computer terminals. The use of TEMPEST is not illegal under the laws of the United States[3], or England. Canada has specific laws criminalizing TEMPEST eavesdropping but the laws do more to hinder surveillance countermeasures than to prevent TEMPEST surveillance. In the United States it is illegal for an individual to take effective counter-measures against TEMPEST surveillance. This leads to the conundrum that it is legal for individuals and the government to invade the privacy of others but illegal for individuals to take steps to protect their privacy. The author would like to suggest that the solution to this conundrum is straightforward. Information on _____________________ 2. TEMPEST is an acronym for Transient Electromagnetic Pulse Emanation Standard. This standard sets forth the official views of the United States on the amount of electromagnetic radiation that a device may emit without compromising the information it is processing. TEMPEST is a defensive standard; a device which conforms to this standard is referred to as TEMPEST Certified. The United States government has refused to declassify the acronym for devices used to intercept the electromagnetic information of non-TEMPEST Certified devices. For this note, these devices and the technology behind them will also be referred to as TEMPEST; in which case, TEMPEST stands for Transient Electromagnetic Pulse Surveillance Technology. The United States government refuses to release details regarding TEMPEST and continues an organized effort to censor the dissemination of information about it. For example the NSA succeeded in shutting down a Wang Laboratories presentation on TEMPEST Certified equipment by classifying the contents of the speech and threatening to prosecute the speaker with revealing classified information. [cite coming]. 3. This Note will not discuses how TEMPEST relates to the Warrant Requirement under the United States Constitution. Nor will it discuss the Constitutional exclusion of foreign nationals from the Warrant Requirement. <New Page> protecting privacy under TEMPEST should be made freely available; TEMPEST Certified equipment should be legally available; and organizations possessing private information should be required by law to protect that information through good computer security practices and the use of TEMPEST Certified equipment. I. INTELLIGENCE GATHERING Spying is divided by professionals into two main types: human intelligence gathering (HUMINT) and electronic intelligence gathering (ELINT). As the names imply, HUMINT relies on human operatives, and ELINT relies on technological operatives. In the past HUMINT was the sole method for collecting intelligence.[4] The HUMINT operative would steal important papers, observe troop and weapon movements[5], lure people into his confidences to extract secrets, and stand under the eavesdrip[6] of houses, eavesdropping on the occupants. As technology has progressed, tasks that once could only be performed by humans have been taken over by machines. So it has been with spying. Modern satellite technology allows troop and weapons movements to be observed with greater precision and from greater distances than a human spy could ever hope to accomplish. The theft of documents and eavesdropping on conversations may now be performed electronically. This means greater safety for the human operative, whose only involvement may be the placing of the initial ELINT devices. This has led to the ascendancy of ELINT over HUMINT because the placement and _____________________ 4. HUMINT has been used by the United States since the Revolution. "The necessity of procuring good intelligence is apparent & need not be further urged -- All that remains for me to add is, that you keep the whole matter as secret as possible. For upon Secrecy, Success depends in Most Enterprises of the kind, and for want of it, they are generally defeated, however well planned & promising a favorable issue." Letter of George Washington (Jul. 26, 1777). 5. "... I wish you to take every possible pains in your powers, by sending trusty persons to Staten Island in whom you can confide, to obtain Intelligence of the Enemy's situation & numbers -- what kind of Troops they are, and what Guards they have -- their strength & where posted." Id. 6. Eavesdrip is an Anglo-Saxon word, and refers to the wide overhanging eaves used to prevent rain from falling close to a house's foundation. The eavesdrip provided "a sheltered place where one could hide to listen clandestinely to conversation within the house." W. MORRIS & M. MORRIS, MORRIS DICTIONARY OF WORD AND PHRASE ORIGINS, 198 (1977). <New Page> monitoring of ELINT devices may be performed by a technician who has no training in the art of spying. The gathered intelligence may be processed by an intelligence expert, perhaps thousands of miles away, with no need of field experience. ELINT has a number of other advantages over HUMINT. If a spy is caught his existence could embarrass his employing state and he could be forced into giving up the identities of his compatriots or other important information. By its very nature, a discovered ELINT device (bug) cannot give up any information; and the ubiquitous nature of bugs provides the principle state with the ability to plausibly deny ownership or involvement. ELINT devices fall into two broad categories: trespassatory and non-trespassatory. Trespassatory bugs require some type of trespass in order for them to function. A transmitter might require the physical invasion of the target premises for placement, or a microphone might be surreptitiously attached to the outside of a window. A telephone transmitter can be placed anywhere on the phone line, including at the central switch. The trespass comes either when it is physically attached to the phone line, or if it is inductive, when placed in close proximity to the phone line. Even microwave bugs require the placement of the resonator cone within the target premises.[7] Non-trespassatory ELINT devices work by receiving electromagnetic radiation (EMR) as it radiates through the aether, and do not require the placement of bugs. Methods include intercepting[8] information transmitted by satellite, microwave, and radio, including mobile and cellular phone transmissions. This information was purposely transmitted with the intent that some intended person or persons would receive it. Non-trespassatory ELINT also includes the interception of information that was never intended to be transmitted. All electronic devices emit electromagnetic radiation. Some of the radiation, as with radio waves, is intended to transmit information. Much of this radiation is not intended to transmit information and is merely incidental to _____________________ 7. Pursglove, How Russian Spy Radios Work, RADIO ELECTRONICS, 89-91 (Jan 1962). 8. Interception is an espionage term of art and should be differentiated from its more common usage. When information is intercepted, the interceptor as well as the intended recipient receive the information. Interception when not used as a term of art refers to one person receiving something intended for someone else; the intended recipient never receives what he was intended to receive. <New Page> whatever work the target device is performing.[9] This information can be intercepted and reconstructed into a coherent form. With current TEMPEST technology it is possible to reconstruct the contents of computer video display terminal (VDU) screens from up to a kilometer distant[10]; reconstructing the contents of a computer's _____________________ 9. There are two types of emissions, conducted and radiated. Radiated emissions are formed when components or cables act as antennas for transmit the EMR; when radiation is conducted along cables or other connections but not radiated it is referred to as "conducted". Sources include cables, the ground loop, printed circuit boards, internal wires, the power supply to power line coupling, the cable to cable coupling, switching transistors, and high-power amplifiers. WHITE & M. MARDIGUIAN, EMI CONTROL METHODOLOGY AND PROCEDURES, 10.1 (1985). "[C]ables may act as an antenna to transmit the signals directly or even both receive the signals and re-emit them further away from the source equipment. It is possible that cables acting as an antenna in such a manner could transmit the signals much more efficiently than the equipment itself...A similar effect may occur with metal pipes such as those for domestic water supplies. ... If an earthing [(grounding)] system is not installed correctly such that there is a path in the circuit with a very high resistance (for example where paint prevents conduction and is acting as an insulator), then the whole earthing system could well act in a similar fashion to an antenna. ... [For a VDU] the strongest signals, or harmonics thereof, are usually between 60-250 MHz approximately. There have however been noticeable exception of extremely strong emissions in the television bands and at higher frequencies between 450-800 MHz. Potts, Emission Security, 3 COMPUTER LAW AND SECURITY REPORT 27 (1988). 10. The TEMPEST ELINT operator can distinguish between different VDUs in the same room because of the different EMR characteristics of both homo and heterogeneous units. "[T]here is little comparison between EMR characteristics from otherwise comparable equipment. Only if the [VDU] was made with exactly the same components is there any similarity. If some of the components have come from a different batch, have been updated in some way, and especially if they are from a different manufacturer, then completely different results are obtained. In this way a different mark or version of the same [VDU] will emit different signals. Additionally because of the variation of manufacturing standards between counties, two [VDUs] made by the same company but sourced from different counties will have entirely different EMR signal characteristics...From this it way be thought that there is such a jumble of emissions around, that it would not be possible to isolate those from any one particular source. Again, this is not the case. Most received signals have <New Page> memory or the contents of its mass storage devices is more complicated and must be performed from a closer distance.[11] The reconstruction of information via EMR, a process for which the United States government refuses to declassify either the exact technique or even its name[12], is not limited to computers and digital devices but is applicable to all devices that generate electromagnetic radiation.[13] TEMPEST is especially effective against VDUs because they produce a very high level of EMR.[14] _____________________ a different line synchronization, due to design, reflection, interference or variation of component tolerances. So that if for instance there are three different signals on the same frequency ... by fine tuning of the RF receiver, antenna manipulation and modification of line synchronization, it is possible to lock onto each of the three signals separately and so read the screen information. By similar techniques, it is entirely possible to discriminate between individual items of equipment in the same room." Potts, supra note 9. For a discussion of the TEMPEST ELINT threat See e.g., Memory Bank, AMERICAN BANKER 20 (Apr 1 1985); Emissions from Bank Computer Systems Make Eavesdropping Easy, Expert Says, AMERICAN BANKER 1 (Mar 26 1985); CRT spying: a threat to corporate security, PC WEEK (Mar 10 1987). 11. TEMPEST is concerned with the transient electromagnetic pulses formed by digital equipment. All electronic equipment radiates EMR which may be reconstructed. Digital equipment processes information as 1's and 0's--on's or off's. Because of this, digital equipment gives off pulses of EMR. These pulses are easier to reconstruct at a distance than the non-pulse EMR given off by analog equipment. For a thorough discussion the radiation problems of broadband digital information see e.g. military standard MIL-STD-461 REO2; White supra note 9, 10.2. 12. See supra note 2. 13. Of special interest to ELINT collectors are EMR from computers, communications centers and avionics. Schultz, Defeating Ivan with TEMPEST, DEFENSE ELECTRONICS 64 (June 1983). 14. The picture on a CRT screen is built up of picture elements (pixels) organized in lines across the screen. The pixels are made of material that fluoresces when struck with energy. The energy is produced by a beam of electrons fired from an electron gun in the back of the picture tube. The electron beam scans the screen of the CRT in a regular repetitive manner. When the voltage of the beam is high then the pixel it is focused upon emits photons and appears as a dot on the screen. By selectively firing the gun as it scans across the face of the CRT, the pixels form characters on the CRT screen. <New Page> ELINT is not limited to governments. It is routinely used by individuals for their own purposes. Almost all forms of ELINT are available to the individual with either the technological expertise or the money to hire someone with the expertise. Governments have attempted to criminalize all use of ELINT by their subjects--to protect the privacy of both the government and the population. II. UNITED STATES LAW In the United States, Title III of the Omnibus Streets and Crimes Act of 1968[15] criminalizes trespassatory ELINT as the intentional interception of wire communications.[16] As originally passed, Title III did not prohibit non- _____________________ The pixels glow for only a very short time and must be routinely struck by the electron beam to stay lit. To maintain the light output of all the pixels that are supposed to be lit, the electron beam traverses the entire CRT screen sixty times a second. Every time the beam fires it causes a high voltage EMR emission. This EMR can be used to reconstruct the contents of the target CRT screen. TEMPEST ELINT equipment designed to reconstruct the information synchronizes its CRT with the target CRT. First, it uses the EMR to synchronize its electron gun with the electron gun in the target CRT. Then, when the TEMPEST ELINT unit detects EMR indicating that the target CRT fired on a pixel, the TEMPEST ELINT unit fires the electron gun of its CRT. The ELINT CRT is in perfect synchronism with the target CRT; when the target lights a pixel, a corresponding pixel on the TEMPEST ELINT CRT is lit. The exact picture on the target CRT will appear on the TEMPEST ELINT CRT. Any changes on the target screen will be instantly reflected in the TEMPEST ELINT screen. TEMPEST Certified equipment gives off emissions levels that are too faint to be readily detected. Certification levels are set out in National Communications Security Information Memorandum 5100A (NACSIM 5100A). "[E]mission levels are expressed in the time and frequency domain, broadband or narrow band in terms of the frequency domain, and in terms of conducted or radiated emissions." White, supra, note 9, 10.1. For a thorough though purposely misleading discussion of TEMPEST ELINT see Van Eck, Electromagnetic Radiation from Video Display units: An Eavesdropping Risk?, 4 Computers & Security 269 (1985). 15. Pub. L. No. 90-351, 82 Stat. 197. The Act criminalizes trespassatory ELINT by individuals as well as governmental agents. cf. Katz v. United States, 389 U.S. 347 (1967) (Fourth Amendment prohibits surveillance by government not individuals.) 16. 18 U.S.C. 2511(1)(a). <New Page> trespassatory ELINT,[17] because courts found that non-wire communication lacked any expectation of p2IIIrivacy.[18] The Electronic Communications Privacy Act of 1986[19] amended Title III to include non-wire communication. ECPA was specifically designed to include electronic mail, inter- computer communications, and cellular telephones. To accomplish this, the expectation of privacy test was eliminated.[20] As amended, Title III still outlaws the electronic interception of communications. The word "communications" indicates that someone is attempting to communicate something to someone; it does not refer to the inadvertent transmission of information. The reception and reconstruction of emanated transient electromagnetic pulses (ETEP), however, is based on obtaining information that the target does not mean to transmit. If the ETEP is not intended as communication, and is therefore not transmitted in a form approaching current communications protocols, then it can not be considered communications as contemplated by Congress when it amended Title III. Reception, or interception, of emanated transient electromagnetic pulses is not criminalized by Title III as amended. III. ENGLISH LAW In England the Interception of Communications Act 1985[21] criminalizes the tapping of communications sent over _____________________ 17. United States v. Hall, 488 F.2d 193 (9th Cir. 1973) (found no legislative history indicating Congress intended the act to include radio-telephone conversations). Further, Title III only criminalized the interception of "aural" communications which excluded all forms of computer communications. 18. Willamette Subscription Television v. Cawood, 580 F.Supp 1164 (D. Or. 1984) (non-wire communications lacks any expectation of privacy). 19. Pub. L. No. 99-508, 100 Stat. 1848 (codified at 18 U.S.C. 2510-710) [hereinafter ECPA]. 20. 18 U.S.C. 2511(1)(a) criminalizes the interception of "any wire, oral or electronic communication" without regard to an expectation of privacy. 21. Interception of Communications Act 1985, Long Title, An Act to make new provision for and in connection with the interception of communications sent by post or by means of public telecommunications systems and to amend section 45 of the Telecommunications Act 1984. <New Page> public telecommunications lines.[22] The interception of communications on a telecommunication line can take place with a physical tap on the line, or the passive interception of microwave or satellite links.[23] These forms of passive interception differ from TEMPEST ELINT because they are intercepting intended communication; TEMPEST ELINT intercepts unintended communication. Eavesdropping on the emanations of computers does not in any way comport to tapping a telecommunication line and therefore falls outside the scope of the statute.[24] ------------------------------------------------------------------------- To find out more about the anon service, send mail to help@anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin@anon.penet.fi.