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1994-06-02 - Re: Black Eye for NSA, NIST, and Denning

Header Data

From: Derek Atkins <warlord@MIT.EDU>
To: koontzd@lrcs.loral.com (David Koontz )
Message Hash: 47f30d714b3577d187e1607c98309a0bb37c00909a45ae6035c08b10939d2b12
Message ID: <9406022313.AA00210@squeamish-ossifrage.mit.edu>
Reply To: <9406022244.AA18607@io.lrcs.loral.com>
UTC Datetime: 1994-06-02 23:13:12 UTC
Raw Date: Thu, 2 Jun 94 16:13:12 PDT

Raw message

From: Derek Atkins <warlord@MIT.EDU>
Date: Thu, 2 Jun 94 16:13:12 PDT
To: koontzd@lrcs.loral.com (David Koontz )
Subject: Re: Black Eye for NSA, NIST, and Denning
In-Reply-To: <9406022244.AA18607@io.lrcs.loral.com>
Message-ID: <9406022313.AA00210@squeamish-ossifrage.mit.edu>
MIME-Version: 1.0
Content-Type: text/plain


The format of the LEAF block is public knowledge.  Here is how it
is formed:


      [80-bit Session key Ks]   [16-bit # ]   [32-bit chip ID]

      [80-bit Unit Key    Ku]

      [80-bit.  {Ks}Ku      ]   [16b {#}Ks]   [32-bit chip ID]

      [128-bit LEAF:  {{Ks}Ku {#}Ks ID}Kf  (Kf == family key)]

Whether or not known plaintext will work is unclear, since you cannot
get {#}Ks (you really don't know what it is outside the chip) and you
also don't know what # is (it is, according to the NSA, a fixed number
in all the chips).

Hope this helps.

-derek

         Derek Atkins, SB '93 MIT EE, G MIT Media Laboratory
       Member, MIT Student Information Processing Board (SIPB)
    Home page: http://www.mit.edu:8001/people/warlord/home_page.html
       warlord@MIT.EDU    PP-ASEL     N1NWH    PGP key available

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