Re: CRC32 vd MD5

From: Matt Harris (mdhat_private)
Date: Mon Jan 06 2003 - 09:32:26 PST

  • Next message: Jamie Lawrence: "Re: CRC32 vd MD5"

    Greg Broiles wrote:
    > 
    > Is this risk (that investigators may be deliberately fabricating or
    > altering evidence) a particularly serious or important one?
    > 
    > It's my impression that existing adversarial/legal systems cope with
    > this risk by allowing for impeachment of witnesses for bias, and by
    > correlating (or failing to correlate) evidence across witnesses or
    > forensic artifacts - e.g., it's one thing for one investigator to say
    > he saw evidence in one logfile or one one hard disk, and another (less
    > likely circumstance) for a team of investigators, perhaps from
    > different agencies or departments, to agree to falsify testimony and
    > evidence about coordinated evidence (e.g., perpetrator's record of mail
    > sent matches the mail logs of two intervening ISP's which also matches
    > mail received on victim's computer).
    
    However, these issues have a great deal of bearing outside of the
    courtroom.  While the authenticity may be in some global way protected
    by laws and common sense of judge and juries, during an investigative
    phase, deliberate tampering by anyone could be an issue.  Of course, if
    replicas exist elsewhere such as in your last example this is less of an
    issue, but if the evidence is tampered with prior to or during the
    investigative phase, when conclusions are being formed, it could well
    lead to untrue statements from very truthful persons.  
    
    It almost feels like you're arguing that authenticity of evidence is
    somehow not important because falsehoods will be weeded out by common
    sense (which I'm sure is not the case anyways, but I feel a desire to
    respond anyways).  Even though that may serve to protect the innocent in
    many cases, it doesn't help to deal with the guilty.  
    
    And what of those persons who deal with the data before it ever reaches
    the courtroom?  Rarely in real-life do you have the same people dealing
    with the entire process from start to finish - in many
    legal/financial/etc organizations this may be the case as large budgets
    have been allocated to computer incident response, but in many other
    organizations a lot of it simply falls to one or two people on the
    technical forensics side who then report to a general counsel or
    inspector general's office or somesuch.  
    
    I should note - I'm jumping out into an area here where I have little
    expertise, as I work solely on the technical side of systems security,
    but this is the view from my little corner of the world.  
    
    /*
     *
     * Matt Harris - Senior UNIX Systems Engineer
     * Smithsonian Institution, OCIO
     *
     */
    
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