David Galindo Sebastià Martín Molleví Paz Morillo Jorge Luis Villar Easy Verifiable Primitives and Practical Public Key Cryptosystems. 69-83 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2851&spage=69 2003 conf/isw/2003 ISC db/conf/isw/isc2003.html#GalindoMMV03