Negar Kiyavash Amir Houmansadr Nikita Borisov Multi-flow Attacks Against Network Flow Watermarking Schemes. 307-320 2008 USENIX Security Symposium http://www.usenix.org/events/sec08/tech/full_papers/kiyavash/kiyavash.pdf conf/uss/2008 db/conf/uss/uss2008.html#KiyavashHB08