This is the pgp key of Microsoft TechNet Security - found at:
http://www.microsoft.com/technet/security/bulletin/notify.mspx
 
They digitally sign all Microsoft Security Bulletins.
 
pub  2048/3103F52B 2000/01/22 Microsoft Security Response Center
                              <secure at microsoft.com>
            Key fingerprint = 5E 39 06 33 D6 B3 97 88
                              F7 76 D9 80 AB 7A 94 32
 
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