A new study shows that terahertz data links, which may play a role in ultra-high-speed wireless data networks of the future, aren’t as immune to eavesdropping as many researchers have assumed. The research, published in the journal自然，表明聪明的窃听者有可能从Terahertz发射器拦截一个信号，而不会在接收器上检测到侵入。
布朗大学工程学院的教授，研究的合着者丹尼尔·米特尔曼（Daniel Mittleman）说：“ Terahertz社区的传统观念是，在不引起攻击的情况下，几乎不可能监视Terahertz的数据链接。”“但是我们表明，在Terahertz领域中未发现的窃听比大多数人的想象更容易，并且当我们考虑设计网络体系结构时，我们需要考虑安全问题。”
由于频率较高，Terahertz辐射can carry up to 100 times more data than the microwaves used in wireless communication today, which makes terahertz an attractive option for use in future wireless networks. Along with enhanced bandwidth, it has also been generally assumed that the way in which high-frequency waves propagate would naturally enhance security. Unlike microwaves, which propagate in wide-angle broadcasts, terahertz waves travel in narrow, very directional beams.
“In microwave communications, an eavesdropper can put an antenna just about anywhere in the broadcast cone and pick up the signal without interfering with the intended receiver,” Mittleman said. “Assuming that the attacker can decode that signal, they can then eavesdrop without being detected. But in terahertz networks, the narrow beams would mean that an eavesdropper would have to place the antenna between the transmitter and receiver. The thought was that there would be no way to do that without blocking some or all of the signal, which would make an eavesdropping attempt easily detectable by the intended receiver.”
Mittleman and colleagues from Brown, Rice University and the University at Buffalo set out to test that notion. They set up a direct line-of-site terahertz data link between a transmitter and receiver, and experimented with devices capable of intercepting signal. They were able show several strategies that could steal signal without being detected—even when the data-carrying beam is very directional, with a cone angle of less than 2 degrees (in contrast to microwave transmission, where the angle is often as large as 120 degrees).
One set of strategies involves placing objects at the very edge of a beam that is capable of scattering a tiny portion of the beam. In order for a data link to be reliable, the diameter of the beam must be slightly larger than the aperture of the receiver. That leaves a sliver of signal for an attacker to work with without casting a detectable shadow on the receiver.
研究人员表明，一块扁平的金属可以将一部分梁的一部分重定向到由攻击者操作的次要接收器。研究人员能够在第二个接收器上获取可用信号，而主接收器没有明显的功率损失。
通过使用梁中的金属缸而不是平板，该团队（从攻击者的角度来看）展示了更加灵活的方法（从攻击者的角度来看）。
“Cylinders have the advantage that they scatter light in all directions, giving an attacker more options in setting up a receiver,” said Josep Jornet, an assistant professor of engineering at Buffalo and a study co-author. “And given the physics of terahertz wave propagation, even a very small cylinder can significantly scatter the signal without blocking the line-of-sight path.”
The researchers went on to demonstrate another type of attack involving a lossless beam splitter that would also be difficult, if not impossible, to detect. The光束放置在发射器前面的分离器将使攻击者能够偷窃足够有用的东西，但并没有太多，以至于它会引发网络管理员之间的警报铃。
研究人员说，最重要的是，尽管与较低的频率相比，与Terahertz链接相关的固有安全性增强功能，但这些安全性改进仍然远非万无一失。
莱斯大学电气和计算机工程教授兼研究合着者爱德华·奈特利（Edward Knightly）说：“自从马可尼（Marconi）时代以来，从窃听者那里获得无线传输一直是一个挑战。”“尽管Terahertzbands take a huge leap in this direction, we unfortunately found that a determined adversary can still be effective in intercepting the signal.”
提交以下：M2M（机器到机器）
