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By Scott Ruoti, University of Tennessee
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Among the many changes brought about by the pandemic is the widespread use of QR codes<\/a>, graphical representations of digital data<\/a> that can be printed and later scanned by a smartphone or other device.
QR codes have a wide range of uses that help people avoid contact with objects and close interactions with other people, including for sharing restaurant menus, email list sign-ups, car and home sales information, and checking in and out of medical and professional appointments.
QR codes are a close cousin of the bar codes on product packaging that cashiers scan with infrared scanners to let the checkout computer know what products are being purchased.
Bar codes store information along one axis, horizontally. QR codes store information in both vertical and horizontal axes, which allows them to hold significantly more data. That extra amount of data is what makes QR codes so versatile.
Anatomy of a QR code<\/a>
<\/strong>While it is easy for people to read Arabic numerals, it is hard for a computer. Bar code<\/a>s encode alphanumeric data as a series of black and white lines of various widths. At the store, bar codes record the set of numbers that specify a product's ID. Critically, data stored in bar codes is redundant. Even if part of the bar code is destroyed or obscured, it is still possible for a device to read the product ID.
QR codes are designed to be scanned using a camera, such as those found on your smartphone. QR code scanning is built into many camera apps for Android and iOS. QR codes are most often used to store web links; however, they can store arbitrary data, such as text or images.
When you scan a QR code, the QR reader in your phone's camera deciphers the code, and the resulting information triggers an action on your phone. If the QR code holds a URL, your phone will present you with the URL. Tap it, and your phone's default browser will open the webpage.
QR codes are composed of several parts: data, position markers, quiet zone and optional logos.
The data in a QR code is a series of dots in a square grid. Each dot represents a one and each blank a zero in binary code, and the patterns encode sets of numbers, letters or both, including URLs. At its smallest this grid is 21 rows by 21 columns, and at its largest it is 177 rows by 177 columns. In most cases, QR codes use black squares on a white background, making the dots easy to distinguish. However, this is not a strict requirement, and QR codes can use any color or shape for the dots and background.
Position markers are squares placed in a QR code's top-left, top-right, and bottom-left corners. These markers let a smartphone camera or other device orient the QR code when scanning it. QR codes are surrounded by blank space, the quiet zone, to help the computer determine where the QR code begins and ends. QR codes can include an optional logo in the middle.
Like barcodes, QR codes are designed with data redundancy. Even if as much as 30% of the QR code is destroyed or difficult to read, the data can still be recovered. In fact, logos are not actually part of the QR code; they cover up some of the QR code's data. However, due to the QR code's redundancy, the data represented by these missing dots can be recovered by looking at the remaining visible dots.
Are QR codes dangerous<\/a>?<\/strong>
QR codes are not inherently dangerous. They are simply a way to store data. However, just as it can be hazardous to click links in emails, visiting URLs stored in QR codes can also be risky in several ways.
The QR code's URL can take you to a phishing website that tries to trick you into entering your username or password for another website. The URL could take you to a legitimate website and trick that website into doing something harmful, such as giving an attacker access to your account. While such an attack requires a flaw in the website you are visiting, such vulnerabilities are common on the internet<\/a>. The URL can take you to a malicious website that tricks another website you are logged into on the same device to take an unauthorized action.
A malicious URL could open an application on your device and cause it to take some action. Maybe you've seen this behavior when you clicked a Zoom link, and the Zoom application opened and automatically joined a meeting. While such behavior is ordinarily benign, an attacker could use this to trick some apps into revealing your data.
It is critical that when you open a link in a QR code, you ensure that the URL is safe and comes from a trusted source. Just because the QR code has a logo you recognize doesn't mean you should click on the URL it contains.
There is also a slight chance that the app used to scan the QR code could contain a vulnerability that allows malicious QR codes to take over your device. This attack would succeed by just scanning the QR code, even if you don't click the link stored in it. To avoid this threat, you should use trusted apps provided by the device manufacturer to scan QR codes and avoid downloading custom QR code apps.
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QR码是如何工作的,是什么让他们危险:计算机科学家解释了吗
二维码是一系列的数据点在正方形网格。每个点代表一个和每个空白零二进制代码,和编码的模式集的数字,字母或两个,包括url。
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斯科特Ruoti,田纳西大学
在许多变化带来的大流行的广泛使用QR码的图形化表达,数字数据可以打印的,后来扫描通过智能手机或其他设备。
QR码有广泛的用途,帮助人们避免接触对象和与别人密切互动,包括共享餐厅菜单,注册邮件列表,汽车和房屋销售信息,并检查医疗专业的任命。
QR码是近亲的产品包装上的条形码收银员结账与红外扫描仪扫描,让计算机知道产品被购买。
条形码存储信息沿着一个轴,横向。二维码信息存储在两个垂直和水平轴,它允许保存更多数据。额外的数据量是QR码那么多才多艺。
解剖学的QR代码
虽然人们容易阅读阿拉伯数字,很难一台电脑。条形码年代编码字母数字数据作为一系列各种宽度的黑色和白色的线。在商店里,条形码记录的数据集指定产品的ID。至关重要的是,数据存储在条形码是多余的。即使条形码被摧毁或模糊的一部分,它仍然是一个设备可以读取产品ID。
二维码被设计成使用相机扫描,如发现在你的智能手机。二维码扫描是许多相机内置Android和iOS应用程序。QR码是最常用于存储网络链接;然而,他们可以存储任意数据,如文本或图像。
当你扫描二维码,QR读者在你的手机相机理解代码,以及由此产生的信息触发一个动作在你的手机上。如果二维码持有一个URL,你的手机将URL。利用它,你的手机的默认浏览器将打开网页。
QR码是由几个部分组成:数据、位置标记,安静的区域和可选的标志。
二维码是一系列的数据点在正方形网格。每个点代表一个和每个空白零二进制代码,和编码的模式集的数字,字母或两个,包括url。在其最小网格是21行21列在其最大是177行177列。在大多数情况下,QR码使用白色背景上的黑色方块,使点容易区分。然而,这并不是一个严格的要求,和QR码可以使用任何颜色或形状的点和背景。
位置标记放置在一个二维码的左上的广场,右上的左下侧的角落。这些标记让智能手机相机或其他设备时东方二维码扫描。QR码四周都是空白的空间,安静的区域,帮助计算机确定二维码开始和结束的地方。二维码可以包括一个可选的标志在中间。
像条形码、二维码与数据冗余设计。即使多达30%的二维码被摧毁或难以阅读,数据仍然可以被恢复。事实上,标志不是二维码的一部分;他们掩盖一些二维码的数据。然而,由于二维码的冗余,这些失踪的点所代表的数据可以恢复通过查看剩余的可见点。
QR码是危险的吗?
QR码本身并不危险。他们只是存储数据的一种方法。然而,正如它可以危害单击电子邮件中的链接,访问url存储在二维码还可以在几个方面是有风险的。
二维码的URL可以带你去钓鱼网站,试图欺骗你输入你的用户名或者密码为另一个网站。URL可以带你到一个合法的网站,欺骗网站做一些有害的,如允许攻击者访问你的帐户。而这样的攻击需要一个缺陷在你访问的网站,这样的漏洞是很常见的互联网。URL可以带你去一个恶意网站,技巧你登录到另一个网站在同一设备未经授权采取行动。
恶意网址可以打开一个应用程序在设备上,因为它采取一些行动了。也许你已经看到这种行为,当你点击变焦链接时,和缩放应用程序自动打开了,参加了一个会议。虽然这种行为通常是良性的,攻击者可以利用这个来诱骗一些应用程序暴露您的数据。
关键是当你打开一个链接在一个二维码,可以确保URL是安全的,来自可信来源。仅仅因为二维码的标志你认识并不意味着你应该点击它所包含的URL。
还有一个微小的机会,用来扫描二维码的应用程序可能包含一个漏洞,允许恶意QR码接管你的设备。这种攻击会成功通过扫描二维码,即使你不点击链接存储在它。为了避免这种威胁,您应该使用受信任的应用程序提供的设备制造商扫描QR码,避免下载自定义二维码应用。
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