Considering that a set of three genes is sufficient for the replication of most retroviruses, the human and simian immunodeficiency viruses (HIV and SIV) exhibit a surprising degree of genomic complexity. HIV-1 contains no less than six open reading frames in addition to the prototypic gag, pol, and env coding sequences (see Figure 1). Two of these supplementary genes, tat and rev, are absolute...

The per-method access control lists of standard internet technologies allow only simple forms of access control to be expressed and enforced. They also fail to enforce a strict need-to-know view of persistent data. Real applications require more flexible security constraints including parameter restrictions, logging of accesses and state-dependent access constraints. In particular, the concept ...