单选题 Clattering keyboards may seem the white noise of the modern age, but they betray more information than unwary typists realise. Simply by analysing audio recordings of keyboard clatter, computer scientists can now reconstruct an accurate transcript of what was typed including passwords. And in contrast with many types of computer espionage, the process is simple, requiring only a cheap microphone and a desktop computer.
Such snooping is possible because each key produces a characteristic click shaped by its position on the keyboard, the vigour and hand position of the typist, and the type of keyboard used. But past attempts to decipher keyboard sounds were only modestly successful, requiring a training session in which the computer matched a known transcript to an audio recording of each key being struck. Thus schooled, the software could still identify only 80% of the characters in a different transcript of the same typist on the same machine. Furthermore, each new typist or keyboard required a fresh transcript and training session, limiting the method's appeal to would-be hackers.
Now, in a blow to acoustic security, Doug Tygar and his colleagues at the University of California, Berkeley, have published details of an approach that reaches 96% accuracy, even without a labelled training transcript. The new approach employs methods developed for speech-recognition software to group together all the similar-sounding keystrokes in a recording, generating an alphabet of clicks. The software tentatively assigns each click a letter based on its frequency, then tests the message created by this assignment using statistical models of the English language. For example, certain letters or words are more likely to occur together - if an unknown keystroke follows a "t", it is much more likely to be an "h" than an "x". Similarly, the words "for example'make likelier bedfellows than"fur example". In a final refinement, the researchers employed a method many students would do well to deploy on term papers: automated spellchecking.
By repeatedly revising unlikely or incorrect letter assignments, Dr. Tygar's software extracts sense from sonic chaos. That said, the method does have one limitation: in order to apply the language model, at least five minutes of the recorded typing had to be in standard English (though in principle any systematic language or alphabet would work). But once those requirements are met, the program can decode anything from epic prose to randomised, ten-character passwords.
This sort of acoustic analysis might sound like the exclusive province of spies and spooks, but according to Dr. Tygar, such attacks are not as esoteric as you might expect. He says it is quite simple to find the instructions needed to build a parabolic or laser microphone on the Internet. You could just point one from outside towards an office window to make a recording. And as he points out, would-be eavesdroppers might not even need their own recording equipment, as laptop computers increasingly come equipped with built-in microphones that could be hijacked.
To protect against these sonic incursions, Dr. Tygar suggests a simple remedy: turn up the radio. His computers were less successful at parsing recordings made in noisy rooms. Ultimately, though, more sophisticated recording gear could overcome even background noise, rendering any typed text vulnerable. Dr. Tygar therefore recommends that typed passwords be phased out, to be replaced with biometric scans or multiple types of authorisation that combine a password with some form of silent verification (clicking on a pre-chosen picture in a selection of images, for example). Loose lips may still sink ships, but his research demonstrates that an indiscrcet keystroke could do just as much damage.

单选题 The word "snooping" in Paragraph 2 means

A. venturing.
B. spying.
C. betrayal.
D. conspiracy.

【正确答案】 B

【答案解析】语义题。由题干定位至第二段首句“Such snooping is possible because each key produces a characteristic click…”，由句中的such snooping回溯至前文 “And in contrast with many types of computer espionage, the process is simple, requiring only a cheap microphone and a desktop computer”，这里明确提到了“计算机间谍活动”，可见snooping与espionage意思相近，都有“窃取”等含义，[B]与之含义相近，故为答案。 [避错] 本题所在句予上下文没有提到冒险活动，[A]无依据；第一段首句中提到了betray，[C]是据此设计的干扰项，但本句中的代词such表明snooping足前文刚刚提到的内容，与相隔甚远的第一句没有关联，排除[C]；conspiracy意为“阴谋”，这与espionage不属于同一语义范畴，排除[D]。

单选题 All the following have an effect on deciphering keyboard sounds in the past EXCEPT

A. the typist.
B. the keyboard.
C. the software.
D. the hacker.

【正确答案】 D

【答案解析】细节题。由题干中的deciphering keyboard sounds定位至第二段第二句，从该句开始分析在过去通过击键的声音解析输入内容的正确率不高的原因。末句指出“Furthermore, each new typist or keyboard required a fresh transcript and training session, limiting the method's appeal to would-be hackers”，这里是说前面谈到的问题“限制了这个方法在黑客群体中的使用”，并非黑客群体影响了解析击键的声音，故[D]为答案。 [避错] 末句明确指出“each new typist or keyboard required a fresh transcript and training session”，这说明在过去不同的打字员，不同的键盘对解析击键声音都有影响，排除[A]和[B]；第三句提到“Thus schooled, the software could still identify only 80% of the characters in a different transcript of the same typist on the same machine.”，可见软件也是影响解码击键声音的因素，排除[C]。

单选题 We can infer that the approach developed by Doug Tygar

A. will bc questioncd by many acoustic security experts.
B. will be welcomed by the majority of the Internet users.
C. may be taken advantage of by people with sinister motive.
D. may be thought highly by the users of computer software.

【正确答案】 C

【答案解析】推断题。由题干中的Doug Tygar定位至第三段。首句指出“Now, in a blow to acoustic security, Doug Tygar and his colleagues at the University of California, Berkeley, have published details of an approach that reaches 96% accuracy, even without a labelled training transcript”，之后对这一解析击键声音的方法进行具体说明。结合第二段末句的“…limiting the method's appeal to would-be hackers”可以推断，新方法精确度高，无需脚本，有可能受到黑客们的青睐，[C]中的sinister motive意为“险恶用心”，可见该项符合文意，故为答案。 [避错] 首句提到“in a blow to acoustic security”，即新方法是对声音安全的挑战，但这里没有提及专家们的反应，[A]为过度推断；文中没有涉及互联网用户对击键解析软件的反应，[B]无依据；同理，文中也没有涉及用户对软件的判断，[D]无依据，排除。

单选题 It can be concluded from the passage that

A. some typed texts might be replaced in the future for security.
B. various methods should be combined to decipher sounds.
C. Dr. Tygar's approach is more prone to be attacked by hackers.
D. background noises will hinder hackers from eavesdropping.

【正确答案】 A

【答案解析】推断题。按照试图顺序及选项内容定位至最后两段。末段第四句指出“Dr. Tygar therefore recommends that typed passwords be phased out, to be replaced with biometric scans or multiple types of authorisation that combine a password with some form of silent verification”，既然解决密码输入时可能通过击键声音被分析出来这一风险只能是用无声的方法来替代，这说明将来可能会出现这种情况，[A]符合文意，故为答案。 [避错] 倒数第二段提到了几种分析击键声音的方法：很容易就能在互联网上找到如何制作抛物面反射传声录音器或者激光麦克风的方法。然后你可以把录音器贴在办公室窗户外来录音，间谍甚至不需要拥有录音设备，他们只需黑掉你的内置麦克即可。但没有提及将几种方法结合起来，排除[B]；第二段首句指出“这种声音分析听起来就像是间谍和内鬼们的专用品，但是根据Tygar博士的研究，类似的攻击行为并不是你想象中的那么神秘”，由此不能得出Tygar博士的新方法更易受到攻击的结论，排除[C]；末段首句提到现在解决被窃听的方法“turn up the radio”，但同时第二句的“ultimately, though, more sophisticated recording gear could overcome even background noise, rendering any typed text vulnerable”说明制造噪音的方法在将来还是会失效的，[D]与此含义不符，排除。

单选题 The author's main purpose of writing this passage is to

A. warn people of the computer security.
B. show his achievement in acoustic security.
C. present the ways to eavesdrop on computer users.
D. tell readers how to distinguish the sounds of keystrokes.

【正确答案】 A

【答案解析】主旨题。本文开篇引入主题，指出通过分析击键声音来分析输入文字这一现象。第二段就过去通过击键的声音解析输入内容的正确率不高这一问题进行说明。接下来指出Dr. Tygar研究的新的解析方法，精确度高，使用方便，具体解释了原理和存在的缺陷。在Tygar博士就该解析软件可能受到黑客的利用进行解释之后，引出末段的结论：Loose lips may still sink ships。可以看出虽然文中大部分是对解析方法进行说明，但文章的重点在于使用键盘时的安全问题，末句的“his research demonstrates that an indiscreet keystroke could do just as much damage”是作者写作的意图，这与文中反复出现的espionage，spying，spooking，hackers等一样，是对电脑使用者的警示。故[A]为答案。 [避错] 文中只是在第三段和第四段具体介绍了Tygar所开发出的新方法，可见他的研究成果只是文章的部分内容，此外，该研究也不是acoustic security(声音安全)方面的成果，排除[B]；倒数第二段提到了如何窃听击键声音的几种方法．这是文章部分细节内容，非主旨，排除[C]；文中虽然解释了击键声音解析软件的编程原理，但作者的意图在末段体现得非常明显，不是告诉读者如何区分不同的击键声音，而是要警示他们注意自己电脑使用时的声音安全问题，排除[D]。