@Article{CEEFx01,
  author = 	 { Dwaine Clarke and Jean-Emile Elien and Carl Ellison and Matt Fredette
                   and Alexander Morcos and Ronald L. Rivest },
  title = 	 { Certificate chain discovery in {SPKI/SDSI}},
  journal = 	 { Journal of Computer Security },
  issn =         { 0926227X },                  
  publisher =    { IOS Press },                  
  OPTyear = 	 { 2001 },
  date =         { 2001 },                  
  issue = 	 { December },
  volume = 	 { 9 },
  number = 	 { 4 },
  pages = 	 { 285--322 },
  keywords =     { certificate, certificate chain, certificate chain discovery, public-key infrastructure, 
                   PKI, SPKI, SDSI, naming, local names, authorization, delegation, threshold subjects },
  abstract =     { 
                  SPKI/SDSI is a novel public-key infrastructure
                  emphasizing naming, groups, ease-of-use, and
                  flexible authorization. To access a protected
                  resource, a client must present to the server a
                  proof that the client is authorized; this proof
                  takes the form of a ``certificate chain'' proving that
                  the client's public key is in one of the groups on
                  the resource's ACL, or that the client's public key
                  has been delegated authority (in one or more stages)
                  from a key in one of the groups on the resource's
                  ACL.  
                  \par 
                  While finding such a chain can be
                  nontrivial, due to the flexible naming and
                  delegation capabilities of SPKI/SDSI certificates,
                  we present a practical and efficient algorithm for
                  this problem of ``certificate chain discovery''. 
                  \par
                  We also present a tight worst-case bound on its
                  running time, which is polynomial in the length of
                  its input.  We also present an extension of our
                  algorithm that is capable of handling ``threshold
                  subjects'', where several principals are required to
                  co-sign a request to access a protected resource.  
                  },
}