Yki Kortesniemi Tero Hasu Jonna Särs A Revocation, Validation and Authentication Protocol for SPKI Based Delegation Systems. 2000 conf/ndss/2000 NDSS http://www.isoc.org/isoc/conferences/ndss/2000/proceedings/023.pdf db/conf/ndss/ndss2000.html#KortesniemiHS00