AceJudge is a system for managing programming contests. AceJudge's basic features include automatic judging of submitted programs, answering to clarification questions about problem descriptions, reevaluation of programs, real time ranking etc.
The iText based PDF sCramblEr allows you to encrypt a PDF using one or more public certificates of the addressees (one or more .cer files). For each .cer file, you can enforce specific PDF permissions: (dis)allow printing, (dis)allow modification,...