Understanding and analyzing information flow is crucial in the evaluation of security critical software systems. Data Flow Logic (DFL) is a domain specific language under development at Rockwell Collins for use in specifying and verifying information flow properties of software written in C. The language leverages source code annotations to enable concise, consumable, abstract specifications of crucial information flow properties. A static analysis engine is also being developed to allow specifications to be verified automatically. This talk will highlight the motivation, methodology and status of the DFL tool suite.