Taint Analysis.

Our use of tainting, inspired by Perl's taint mode [32], bears some resemblance to a Biba integrity model [6] and thus is distantly related to previous work on enforcing information flow policies through typing [29,39,40]. However, because we do not have to deal with maliciously constructed code, we avoid the need to solve many of the most vexing challenges (e.g., covert channels) in enforcing information flow policies.