首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Leaks from Edward Snowden, a system’s administrator turned whistleblower at the National Security Agency(NSA), America’s signals
Leaks from Edward Snowden, a system’s administrator turned whistleblower at the National Security Agency(NSA), America’s signals
admin
2016-09-24
98
问题
Leaks from Edward Snowden, a system’s administrator turned whistleblower at the National Security Agency(NSA), America’s signals-intelligence agency, have confirmed that the Internet is insecure, and that modern spy agencies can—and do, on an industrial scale—tap virtually any form of online communication. But perhaps the most acute embarrassment so far has been caused by the revelation that the NSA may have been listening to phone calls made by the leaders of America’s allies, most notably those of the German chancellor, Angela Merkel. But how exactly is it done?
A mobile phone is essentially a telephone with a radio attached. Anyone can listen in on the radio waves travelling between a handset and the base station to which it is connected. To prevent casual eavesdropping, phones often(although not always)use encryption, which disarranges the data so that only the intended recipient can make sense of it. But not all encryption is created equal. The encryption used in second-generation(2G)phones—a technology that dates back to 1991—is weak, and readily cracked by modern computers. The 3G standard includes stronger disarranging, although it is still not perfect. 4G, the newest standard, currently being used around the world, likewise offers more competent encryption—although documents leaked by Edward Snowden suggest that the spies are pressuring manufacturers to put secret "back doors" into their products.
But getting involved in cryptography isn’t always necessary. Spy agencies can obtain details from telephone companies, either by asking them to cooperate or forcing them to. Another option is to impersonate the mobile network itself, by setting up a fake base-station and persuading the target’s phone to connect to it. At a hacker conference in 2010, a security researcher called Chris Paget gave a detailed demonstration of how this works, using less than $ 2, 000 of off-the-shelf equipment(a fake base-station can instruct phones that connect to it to do all sorts of things, such as turn off their encryption). Police forces around the world use a similar gear to silently listen in on calls made by their targets. A recent book describes how the FBI has quietly removed several such fake base-stations— run by foreign embassies—from around Washington, D. C.
Nor is it just calls. Text messages can also be snatched. Modern smartphones are general-purpose computers. Users store e-mails on them, fix their position with satellite navigation systems, and even use them for banking, making them very juicy targets indeed. Even if the phones themselves are secure, it is far from clear how secure the behind-the-scenes servers run by Google and Apple, which control the Android and iOS platforms respectively, really are. For the non-spies, there are cheaper, simpler options that often work, too. This week several journalists in Britain are standing trial for hacking the voicemail messages of everyone from serving politicians to murdered schoolchildren. Their methods were low-tech but effective: they smooth-talked employees of mobile-phone companies into handing over the four-digit pass codes that protect their customers’ voicemail accounts. Or else they simply guessed them, betting that the phone owners either hadn’t changed them from default settings or had chosen easy-to-remember ones, such as 1 — 2 — 3 — 4. Whether the NSA used low-or high-tech methods to tap Mrs. Merkel’s phone remains a mystery—for now, at least.
How can encryption prevent casual eavesdropping?
选项
A、By stopping the usual radio waves.
B、By disconnecting a telephone to a radio.
C、By making the information incomprehensible.
D、By creating equal code pages.
答案
C
解析
加密金钥如何防止偶然的窃听?使信息无法理解。根据第二段第三句,为了防止偶然的窃听,电话往往(尽管并非总是如此)使用加密金钥,即一种特殊的代码,代码将数据打乱,只让蓄意的接收者理解数据。
转载请注明原文地址:https://kaotiyun.com/show/sJGO777K
0
考博英语
相关试题推荐
Onlytwocountriesintheadvancedworldprovidenoguaranteeforpaidleavefromworktocareforanewbornchild.Lastspring
Concernwithmoney,andthenmoremoney,inordertobuytheconveniencesandluxuriesofmodernlife,hasbroughtgreatchanges
Whowouldhavethoughtwewouldbecomeaplanetof"ologies"?There’sbiology,psychology,herpetology,etymology,andgeologyj
Today,theTowerofLondonisoneofthemostpopulartourist【C1】______andattractsoverthreemillionvisitorsayear.Itw
TheculturesofChinaandJapanhavesharedmanyfeatures,buteachhasusedthemaccordingtoitsnational______.
Schoolbuildingsthemselvescanreflectliberalorconservativeviewsaboutwhatshouldgooninaclassroom.Theearliestschoo
IknowthatifIstartwatchingsoapoperaIwillimmediatelybecomehopelessly______toit.
Youprobablyknowthatit’sbetterforbothyouandtheenvironmentifyoubuyanorganictomatoinsteadofonethat’sbeendous
Theproblemisinherentand______inanydemocracy,butithasbeenmoresevereinoursduringthepastquarter-centurybecauseo
Onecanunderstandothersmuchbetterbynotingtheimmediateandfleetingreactionsoftheireyesand______toexpressedthought
随机试题
乳母的合理膳食原则。
下列哪种新生的细胞是机化时出现的特征性细胞?
主治外感热病气分高热证,及肺热、胃火、肝火、心火等脏腑火热证主治外感热病热人营血之高热神昏谵语,及火热内生之血热妄行诸证
患者,女性,33岁,因心悸及颈部明显搏动感来诊。查体:血压130/50mmHg;X线胸片示左心室扩大、主动脉弓突出并有明显搏动感。该患者最可能发生的情况是
()于1994年颁布了《工程咨询单位资格认定暂行办法》。
供热站试运行要求()。
下列国际工程投标报价的策略中,()的特点是不着眼一次投标效益,用低报价吸引投标人。
下列关于原始创新、集成创新和引进消化吸收再创新的表述正确的有()。
太平洋战争(华南师范大学2004年世界近现代史真题)
世界上公认的第一台电子计算机是______。
最新回复
(
0
)