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                   B O S T O N   U N I V E R S I T Y
                                       
                      Computer Science Department
                                       
                          C O L L O Q U I U M

         Asymmetric MACs, Secure IP Multicast, and other easy Crypto

                              Gene Itkis
				 NKS

 			   Thursday, May 13
                                      
                               4:00 PM
                       (Coffee served at 3:45pm)

                                       
                         Seminar Room / MCS 135
                                       

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    We consider some problems arising in group communication. Typical examples
    of such group communication include Internet (IP) Multicast, and Pay-TV
    broadcasting. In these cases, all the communication might be seen by all,
    but only the members of the "subscribers" group can decipher them . The
    group membership may change: some subscribers cancel their subscription,
    while new ones join.

    One issue arising in this setting is the efficient key management: how to
    maintain the above invariant that all members and only the members have the
    group key used to encrypt the group messages.

    Another issue is authentication of the message source. For this problem the
    Public Key Cryptography techniques could be applied. We develop an
    alternative approach, based of Message Authentication Codes (MAC). MACs are
    essentially similar to hash functions, are very efficient and are widely
    used (e.g. IPSEC). We define Asymmetric MACs, which use MACs as a primitive,
    but achieve certain asymmetric properties similar to the Public Key
    techniques.

    The talk will focus on the authentication issues, but if time allows, key
    management and other problems might be discussed.  The talk is intended for 
    general audience and requires no prior knowledge of cryptography.

    
    
    Host: Steve Homer (homer@cs.bu.edu)

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