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I first meet Yang Qing at Blackhat 2014 and was pleasantly surprised to learn such a young face leads a team on hardware security.Since then he has accomplished several works，ranging from GPS spoofing to designing various gadgets for protecting users’security and privacy.When he told me about their book on wireless security，I was delighted because wireless security is such an important topic and needs much more attention and talents than what we have today.

With the proliferation of wireless technologies，numerous emerging wireless devices have been woven into the fabric of our daily life，ranging from controlling our home appliances to making our vehicles automatically seek for help in emergency situations.Unfortunately，the security on these wireless devices has almost always lagged behind the plethora of the interests in integrating wireless technologies into almost everything.Granted that manufactories and designers have gradually increased their motivation in securing their devices，we have a long way to go.Spreading knowledge on wireless security is one of the critical efforts towards securing wireless devices，and this book serves as a good endeavor along this goal.

Many academic books on wireless communication and wireless security are available，and many of them focus on the theoretical principles.This book is a collection of the systems works that Qing and his team have carried out in the past few years as well as the state of the art.The book covers a wide range of wireless devices，such as RFID，Bluetooth，Zigbee，GPS，and it contains many results，plots，screen-snapshots from real world experiments.

This book can serve as a good tutorial for those who want to have their hand dirty and reproduce the prior findings.It can also be a good reference book for those who want to find out the off-the-shelf tools for exploring the wireless world.I hope this book can help to foster talents in wireless security and to teach them necessary skills to secure the wireless world for many years to come.

徐文渊（浙江大学教授，南卡大学终身教授）