Von Welch Frank Siebenlist Ian T. Foster John Bresnahan Karl Czajkowski Jarek Gawor Carl Kesselman Sam Meder Laura Pearlman Steven Tuecke Security for Grid Services. 48-57 2003 conf/hpdc/2003 HPDC http://csdl.computer.org/comp/proceedings/hpdc/2003/1965/00/19650048abs.htm db/conf/hpdc/hpdc2003.html#WelchSFBCGKMPT03