TUCoPS :: Hardware Hacks :: tempest.txt

Eavesdropping on the electromagnetic emanations of electronic equipment: the laws of Canada, England and the United States

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

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

(c) 1990 Christopher J. Seline
<Start Print Job>
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                                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.


          1.  Undelivered  speech  of  President  John  F.  Kennedy, Dallas
          Citizens Council (Nov. 22, 1963) 35-36.

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                    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. 

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          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).

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          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
               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.

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          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

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          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.

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               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

          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).

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          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
               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.

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          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]

                                IV. CANADIAN LAW
               Canada has taken direct steps to limit eavesdropping on
          computers.    The Canadian  Criminal  Amendment Act  of 1985


          22.  Interception of Communications Act 1985    1, Prohibition on
               (1) Subject to the  following provisions of this section,  a
               person who  intentionally intercepts a communication  in the
               course of its  transmission by post or by  means of a public
               telecommunications system shall be guilty  of an offence and
                    (a) on summary  conviction, to a fine not exceeding the
                    statutory maximum;
                    (b) on conviction on indictment,  to imprisonment for a
                    term not exceeding two years or to a fine or to both.

          23.  Tapping  (aka  trespassatory eavesdropping)  is  patently in
          violation  of the statute.  "The  offense created by section 1 of
          the Interception of Communications Act 1985 covers those forms of
          eavesdropping on computer communications  which involve "tapping"
          the wires along  which messages  are being passed.   One  problem
          which  may  arise,  however,  is  the  question  of  whether  the
          communication in question  was intercepted in  the course of  its
          transmission by  means of a public telecommunications system.  It
          is technically possible  to intercept a communication  at several
          stages in its transmission,  and it may be a question  of fact to
          decide the stage  at which it enters the "public" realm.  THE LAW

          24.  "There are  also forms of  eavesdropping which the  Act does
          not cover.  For  example. eavesdropping on a V.D.U.  [referred to
          in  this text as a CRT] screen  by monitoring the radiation field
          which surrounds it  in order to  display whatever appears on  the
          legitimate  user's  screen on  the  eavesdropper's screen.   This
          activity would not  seem to  constitute any criminal  offence..."

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          criminalized indirect access  to a computer service.[25]   The
          specific reference  to an  "electromagnetic device"  clearly
          shows the intent  of the legislature  to include the use  of
          TEMPEST ELINT equipment within the ambit of the legislation.
               The limitation of obtaining "any computer service" does
          lead to  some confusion.   The Canadian legislature  has not
          made  it  clear  whether  "computer  service"  refers  to  a
          computer  service  bureau  or  merely   the  services  of  a
          computer.    If  the  Canadians  had  meant  access  to  any
          computer,  why  did they  refer  to any  "computer service".
          This   is   especially   confusing   considering   the   al-
          encompassing language  of (b)  'any function  of a  computer
               Even   if   the   Canadian   legislation   criminalizes
          eavesdropping  on  all  computers,  it  does not  solve  the
          problem  of  protecting  the privacy  of  information.   The
          purpose  of  criminal law  is  to control  crime.[26]   Merely
          making  TEMPEST  ELINT  illegal will  not  control  its use.
          First, because  it  is an  inherently  passive crime  it  is
          impossible to detect and hence punish.  Second, making  this
          form of  eavesdropping  illegal without  taking a  proactive
          stance  in  controlling  compromising emanations  gives  the
          public a false sense of security.   Third, criminalizing the
          possession of a TEMPEST ELINT  device prevents public sector
          research into countermeasures.   Finally,  the law will  not
          prevent eavesdropping on private information held in company
          computers unless  disincentives are given for companies that
          do not take sufficient precautions against eavesdropping and
          simple, more common, information crimes.[27]

          25.   301.2(1) of the  Canadian criminal code states  that anyone

          ... without color of right,
          (a) obtains, directly or indirectly, any computer service,
          (b)  by  means  of  an  electromagnetic  ...   or  other  device,
          intercepts  or  causes  to  be  intercepted, either  directly  or
          indirectly, any function of  a computer system ... [is  guilty of
          an indictable offence].

          GUIDELINES MANUAL (1988) (Principles  Governing the Redrafting of
          the Preliminary Guidelines "g." (at an unknown page)) 

          27.  There has been great debate over  what exactly is a computer
          crime.    There  are  several  schools  of  thought.    The  more
          articulate school, and the one to  which the author adheres holds
          that  the category  computer crime  should be  limited to  crimes
          directed against computers; for example, a terrorist destroying a
          computer  with explosives would fall into  this category.  Crimes
          such as  putting  ghost  employees  on  a  payroll  computer  and

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                                  V. SOLUTIONS
               TEMPEST ELINT  is passive.   The  computer or  terminal
          emanates  compromising radiation which is intercepted by the
          TEMPEST device  and reconstructed  into useful  information.
          Unlike conventional  ELINT there  is no  need to  physically
          trespass or even come near the target.  Eavesdropping can be
          performed from a nearby office or even a van parked within a
          reasonable distance.   This means  that there is  no classic
          scene of the crime; and little or  no chance of the criminal
          being discovered in the act.[28]  
               If the crime is discovered it will be ancillary to some
          other  investigation.    For example,  if  an  individual is
          investigated for insider  trading a search of  his residence
          may yield a TEMPEST ELINT device.   The device would explain
          how the defendant was obtaining  insider information; but it
          was the insider trading, not the  device, that gave away the
               This  is  especially  true  for illegal  TEMPEST  ELINT
          performed by the state.  Unless the perpetrators are  caught
          in the act  there is  little evidence  of their  spying.   A
          trespassatory bug can be detected and located; further, once
          found it provides tangible evidence that a crime took place.
          A TEMPEST ELINT device by its inherent passive nature leaves
          nothing to detect.   Since the government is less  likely to
          commit an ancillary crime which might be detected there is a
          very small chance  that the spying will  ever be discovered.
          The  only way to  prevent eavesdropping is  to encourage the
          use of  countermeasures: TEMPEST  Certified[29] computers  and
          collecting their pay are merely  age-old accounting frauds; today
          the  fraud involves a computer because  the records are kept on a
          computer.  The  computer is merely ancillary to  the crime.  This
          has been mislabeled  computer crime and should merely be referred
          to as a fraud perpetrated with  the aid of a computer.   Finally,
          there are information  crimes.  These  are crimes related to  the
          purloining or  alteration of information.  These  crimes are more
          common and more profitable due to  the computer's ability to hold
          and access great amounts of information.   TEMPEST ELINT can best
          be categorized as a information crime.

          28.  Compare, for  example, the  Watergate breakin  in which  the
          burglars  were discovered  when they  returned to  move  a poorly
          placed spread spectrum bug.

          29.  TEMPEST Certified refers  to the  equipment having passed  a
          testing and  emanations regime specified  in NACSIM 5100A.   This
          classified document sets forth the emanations levels that the NSA
          believes digital equipment can give  off without compromising the
          information it  is processing.   TEMPEST  Certified equipment  is
          theoretically secure against TEMPEST eavesdropping.  

<New Page>
               In merely making  TEMPEST ELINT  illegal the public  is
          given the  false impression  of security;  they lulled  into
          believing  the  problem  has been  solved.    Making certain
          actions illegal does not prevent them  from occurring.  This
          is  especially  true  for  a  TEMPEST  ELINT  because it  is
          undetectable.  Punishment is an empty  threat if there is no
          chance of being  detected; without detection there can be no
          apprehension and conviction.   The only way  to prevent some
          entity  from eavesdropping  on  one's  computer or  computer
          terminal is  for the equipment not to  give off compromising
          emanation; it must be TEMPEST Certified.
               The United  States can solve  this problem by  taking a
          proactive  stance on compromising  emanations.  The National
          Institute of Standards and Technology  (NIST[30]) is in charge
          of  setting  forth standards  of  computer security  for the
          private  sector.   NIST  is  also charged  with  doing basic
          research to advance the art of computer security.  Currently
          NIST does not discuss TEMPEST with  the private sector.  For
          privacy's sake,  this policy must be changed  to a proactive
          one.  The NIST should publicize  the TEMPEST ELINT threat to
          computer  security and  should set  up a  rating system  for
          level  of  emanations  produced   by  computer  equipment.[31]
          Further,  legislation  should  be  enacted  to  require  the
          labeling  of  all computer  equipment    with  its level  of
          emanations and whether it is TEMPEST Certified.  Only if the
          public  knows of the  problem can it begin  to take steps to
          solve it.
               Title III makes  possession of a surveillance  device a
          crime,  unless  it   is  produced  under  contract   to  the
          government.  This means that  research into surveillance and
          counter-surveillance   equipment   is  monopolized   by  the
          government and a  few companies working under  contract with
               NACSIM 5100A is  classified, as are all  details of TEMPEST.
          To  obtain  access to  it, contractor  must  prove that  there is
          demand within  the government for the specific  type of equipment
          that intend to  certify.  Since  the standard is classified,  the
          contractors can not sell the equipment to non-secure governmental
          agencies or the public.  This prevents reverse engineering of the
          standard  for its physical  embodiment, the  Certified equipment.
          By  preventing  the   private  sector  from  owning   this  anti-
          eavesdropping equipment,  the NSA has  effectively prevented  the
          them from protecting the information in their computers. 

          30.  Previously the Bureau of Standards.   The NIST is a division
          of the Commerce Department.

          31.  In this case computer equipment would include all peripheral
          computer equipment.  There is no use is using a TEMPEST Certified
          computer if the printer or the modem are not Certified.

<New Page>
          the government.   If TEMPEST eavesdropping  is criminalized,
          then possession of TEMPEST ELINT equipment will be criminal.
          Unfortunately,this  does  not  solve the  problem.    Simple
          TEMPEST ELINT  equipment is easy  to make.   For just  a few
          dollars  many  older  television  sets  can be  modified  to
          receive and  reconstruct  EMR.    For less  than  a  hundred
          dollars a more  sophisticated TEMPEST ELINT receiver  can be
               The  problem  with  criminalizing  the  possession   of
          TEMPEST ELINT equipment is  not just that the law  will have
          little effect on the use of such equipment, but that it will
          have a  negative effect  on counter-measures  research.   To
          successfully   design   counter-measures  to   a  particular
          surveillance  technique  it  is  vital  to have  a  complete
          empirical  understanding   of  how  that   technique  works.
          Without  the right  to  legally manufacture  a  surveillance
          device there is no possible way for a researcher to have the
          knowledge to  produce an effective  counter-measures device.
          It  is  axiomatic:  without  a  surveillance device,  it  is
          impossible to test a counter-measures device.  
               A number of  companies produce  devices to measure  the
          emanations from electrical equipment.  Some of these devices
          are  specifically   designed  for   bench  marking   TEMPEST
          Certified equipment.  This does not  solve the problem.  The
          question  arises:  how   much  radiation  at   a  particular
          frequency  is compromising?  The  current answer is to refer

          32.  The  NSA  has tried  to  limit the  availability  of TEMPEST
          information to prevent the spread of the devices.
               For a discussion of the  First Amendment and prior restraint
          See, e.g. The United  States of America v. Progressive,  Inc. 467
          F.Supp 990 (1979, WD Wis.)(magazine intended to publish plans for
          nuclear  weapon; prior  restraint injunction  issued),  reh. den.
          United States v. Progressive  Inc. 486 F.Supp 5 (1979,  WD Wis.),
          motion  den  Morland  v. Sprecher  443  US  709 (1979)(mandamus),
          motion denied  United States  v. Progressive,  Inc. 5  Media L  R
          (1979, 7th Cir.), dismd. without op. U.S. v. Progressive, Inc 610
          F.2d 819 (1979, 7th Cir.); New York Times, Co. v.  United States,
          403  U.S.  713 (1971)(per  curium)(Pentagon Papers  case: setting
          forth prior  restraint standard  which government  was unable  to
          Balance  Between Scientific  Freedom  and  NAtional Security,  23
          JURIMETRICS  J. 1  (1982)(current  laws and  regulations limiting
          scientific and  technical expression exceed the  legitimate needs
          of national security); Hon. M.  Feldman, Why the First  Amendment
          is not Incompatible  with National Security, HERITAGE  FOUNDATION
          REPORTS (Jan.  14, 1987).  Compare Bork,  Neutral Principles  and
          Some First Amendment Problems,  47 IND. L. J. 1  (First Amendment
          applies only to  political speech); G.  Lewy, Can Democracy  Keep
          Secrets, 26  POLICY REVIEW 17  (1983)(endorsing draconian secrecy
          laws mirroring the English system).

<New Page>
          to NACSIM  5100A.   This document  specifies the  emanations
          levels suitable  for Certification.   The  document is  only
          available  to United  States  contractors having  sufficient
          security  clearance  and  an  ongoing  contract  to  produce
          TEMPEST Certified computers  for the  government.   Further,
          the correct levels are specified by the NSA and there  is no
          assurance that, while these levels are sufficient to prevent
          eavesdropping by unfriendly operatives,  equipment certified
          under NACSIM  5100A will have  levels low enough  to prevent
          eavesdropping by the NSA itself.
               The  accessibility  of  supposedly  correct  emanations
          levels  does  not solve  the  problem of  preventing TEMPEST
          eavesdropping.     Access   to  NACSIM   5100A   limits  the
          manufacturer to selling the equipment  only to United States
          governmental  agencies  with  the  need  to  process  secret
          information.[33]  Without  the right to possess  TEMPEST ELINT
          equipment  manufacturers  who  wish to  sell  to  the public
          sector cannot determine what a  safe level of emanations is.
          Further  those  manufacturers with  access  to  NACSIM 5100A
          should  want  to  verify that  the  levels  set  out in  the
          document are, in  fact, low enough to  prevent interception.
          Without an actual  eavesdropping device with which  to test,
          no   manufacturer  will   be   able  to   produce  genuinely
          uncompromising equipment.

               Even if the  laws allow ownership of  TEMPEST Certified
          equipment by the public, and even  if the public is informed
          of  TEMPEST's   threat  to  privacy,   individuals'  private
          information will not necessarily  by protected.  Individuals
          may  choose to  protect their  own information on  their own
          computers.  Companies  may choose  whether to protect  their
          own  private  information.    But  companies that  hold  the
          private information of  individuals must  be forced to  take
          steps to protect that information.
               In  England  the  Data  Protection  Act 1984[34]  imposes
          sanctions   against   anyone   who   stores   the   personal
          information[35] on  a computer  and fails  to take  reasonable

          33.  For  example, the  NSA has  just recently  allowed the  Drug
          Enforcement Agency (DEA) to  purchase TEMPEST Certified  computer
          equipment.    The DEA  wanted  secure computer  equipment because
          wealthy  drug   lords  had   were  using   TEMPEST  eavesdropping

          34.  An  Act  to  regulate  the  use of  automatically  processed
          information relating to individuals and the provision of services
          in respect of such information.
               -Data Protection Act 1984, Long Title.

          35.  "Personal data"  means data consisting  of information which
          relates to a  living individual who  can be identified from  that

<New Page>
          measures to prevent disclosure of that information.  The act
          mandates  that  personal  data  may  not  be  stored  in any
          computer  unless  the  computer bureau  or  data  user[36] has
          registered under the  act.[37]    This provides for a  central
          registry  and  the tracking  of  which companies  or persons
          maintain databases of personal information.   Data users and
          bureaux must  demonstrate a  need and  purpose behind  their
          possession of personal data.
               The act  provides tort  remedies to  any person  who is
          damaged by disclosure  of the  personal data.[38]   Reasonable
          care to  prevent the  disclosure  is a  defense.[39]   English
          information (or from that and other information in the possession
          of the data user), including any  expression of opinion about the
          individual but not any  indication of the intentions of  the data
          user in respect of that individual.
               -Data Protection Act 1984   1(3)

          36.  "Data user" means  a person  who holds data,  and a  persons
          "Holds" data if --
               (a) the data form part of a collection of  data processed or
               intended to be  processed by or on behalf  of that person as
               mentioned in  subsection (2) above; [subsection  (2) defines
               "data"] and
               (b) that person (either  alone or jointly or in  common with
               other persons)  controls the  contents and  use of  the data
               comprised in the collection; and
               (c) the data are in the form in which  they have been or are
               intended to be processed as mentioned in paragraph (a) above
               or (though not  for the time being  in that form) in  a form
               into which they have been converted after being so processed
               and  with  a  view  to  being  further  so  processed  on  a
               subsequent occasion.
               - Data Protection Act   1(5).

          37.  Data Protection Act 1984,   4,5.

          38.  An individual who is the subject of personal data held  by a
          data user... and who  suffers damage by reason of  (1)(c) ... the
          disclosure of the  data, or  access having been  obtained to  the
          data without  such authority as  aforesaid shall  be entitled  to
          compensation from  the data  user... for any  distress which  the
          individual has  suffered  by  reason of  the  ...  disclosure  or
               - Data Protection Act 1984   23.

          39.  ... it shall  be a defense to  prove that ... the  data user
          ...  had  taken  such  care  as  in  all  the  circumstances  was
          reasonably required  to prevent  the... disclosure  or access  in
               Data Protection Act 1984   23(3)

<New Page>
          courts  have not yet  ruled what level  of computer security
          measures  constitute  reasonable  care.     Considering  the
          magnitude of invasion possible with  TEMPEST ELINT it should
          be  clear  by now  that  failure  to use  TEMPEST  Certified
          equipment is prima facie unreasonable care.
               The Remedies section of the  act provides incentive for
          these  entities to provide  successful protection  of person
          data from disclosure  or illicit access.  Failure to protect
          the data will  result in monetary loss.  This  may be looked
          at from the economic efficiency  viewpoint as allocating the
          cost  of  disclosure the  persons  most able  to  bear those
          costs, and also most able to prevent disclosure.  Data users
          that  store   personal  data  would  use  TEMPEST  Certified
          equipment as part of their computer security plan, thwarting
          would-be eavesdroppers.  
               The Data Protection  Act 1984  allocates risk to  those
          who can  bear it best and provides  an incentive for them to
          keep other  individuals' data private.   This act  should be
          adopted by the United States as part of a full-spectrum plan
          to combat TEMPEST eavesdropping.  Data users are in the best
          position  to  prevent  disclosure  through  proper  computer
          security.    Only by  making  them  liable for  failures  in
          security can we begin to rein in TEMPEST ELINT.

                 Do not  criminalize TEMPEST ELINT.   Most crimes that
          TEMPEST ELINT would aid, such a insider trading, are already
          illegal; the current laws are adequate.
                 The  National Institute of  Standards and  Technology
          should immediately begin  a program  to educate the  private
          sector about TEMPEST.  Only if  individuals are aware of the
          threat  can  they  take  appropriate precautions  or  decide
          whether any precautions are necessary.
                   Legislation  should  be   enacted  to  require  all
          electronic  equipment to  prominently display  its level  of
          emanations  and  whether  it  is   TEMPEST  Certified.    If
          individuals are to choose to protect themselves they must be
          able  to  make  a  informed   decision  regarding  how  much
          protection is enough.
                 TEMPEST  Certified equipment  should be available  to
          the private  sector.   The current  ban on  selling to  non-
          governmental  agencies  prevents  individuals  who  need  to
          protect information from having the technology to do so.
                 Possession of  TEMPEST ELINT equipment should  not be
          made  illegal.   The  inherently  passive nature  and simple
          design  of  TEMPEST ELINT  equipment  means that  making its
          possession illegal  will not deter  crime; the units  can be
          easily manufactured and are impossible  to detect.  Limiting
          their   availability   serves   only   to   monopolize   the
          countermeasures research, information, and equipment for the
          government;   this   prevents   the  testing,   design   and

<New Page>
          manufacture of counter-measures by the private sector.
                 Legislation mirroring  England's Data Protection  Act
          1984 should be  enacted.  Preventing disclosure  of personal
          data  can  only be  accomplished  by giving  those companies
          holding the data a reason to protect  it.  If data users are
          held liable for  their failure  to take reasonable  security
          precautions they  will  begin to  take  reasonable  security
          precautions,  including   the  use   of  TEMPEST   Certified

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