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Showing posts from April, 2011

What's the problem with Microsoft Word?

2008 HowStuffWorks
In 2006 and 2007, major security flaws were discovered in Microsoft Word. In the last two months of 2006 alone, at least four major security flaws involving Microsoft Word were revealed. All are "zero day" flaws, meaning Microsoft and security organizations became aware of them at the same time that destructive hackers became aware of them. In many "zero day" cases, it's the exploitation of the flaw that brings it to the attention of the software companies; in other cases, the software companies announce the flaw and hackers immediately take advantage of it before a patch can be released. The strange thing about these Word problems is that almost eight weeks after the flaws were exploited by attackers, Microsoft still hadn't released a patch to fix it.The first in this string of security holes popped up in early December 2006. This flaw affects computers running Word 2000, 2002 and 2003; Word 2004 for Mac and Word 2004 version X fo…

How facebook works

Some people are online social butterflies, deftly managing to interact with hundreds of Facebook friends on a daily basis. To them, there's no challenge in wading through a dozen event invites, wishing a happy birthday to the appropriate people, responding to Wall posts and making the next move in one of the thousands of games permeating the site.For the rest of us, Facebook can sometimes seem a little overwhelming. If you've got a lot of Facebook friends, you may find it impossible to keep up with everything. And if your friends are the sensitive type, you may give off the impression that you don't care about them. There's nothing quite like finding out a friend is in a tizzy because you didn't respond to an invite on Facebook to go bowling.Then there are the people who'd rather never get on Facebook at all. As our culture embraces social networking sites and services, people begin to feel the pressure to participate. That might not be a big deal to…
Imagine driving to a job interview and realizing that you're lost. Your first impulse would probably be to call the business that's interviewing you and ask for directions. But if you're not sure where you are, getting directions can be tricky.But suppose you use your phone for another purpose -- to figure out exactly where you are and to get turn-by-turn directions to where you're going. New phones that include global positioning system (GPS) receivers can do exactly that. With the right software or service package, they can pinpoint your location, give directions to your destination and provide information about nearby businesses.In this article, we'll review the basics of how cell phones and GPS receivers work. Then, we'll explore how phones combine these technologies.Cell Phone Basics
A cell phone is basically a sophisticated two-way radio. Towers and base stations, arranged into a network of cells, send and receive radio signals. Cell phones contain low-po…

ROBOTICS

Want a robot to cook your dinner, do your homework, clean your house, or get your groceries? Robots already do a lot of the jobs that we humans don't want to do, can't do, or simply can't do as well as our robotic counterparts. In factories around the world, disembodied robot arms assemble cars, delicately place candies into their boxes, and do all sorts of tedious jobs. There are even a handful of robots on the market whose sole job is to vacuum the floor or mow your lawn.Robots Image Gallery
Photo courtesy Honda Motor Co., Ltd.
Honda's ASIMO robot. See more pictures of robots.

Many of us grew up watching robots on TV and in the movies: There was Rosie, the Jetsons' robot housekeeper; Data, the android crewmember on "Star Trek: The Next Generation"; and of course, C3PO from "Star Wars." The robots being created today aren't quite in the realm of Data or C3PO, but there have been some amazing advances in their technology. Honda engi…
Pros and Cons There are several ways a security system can verify that somebody is an authorized user. Most systems are looking for one or more of the following: What you have What you know Who you are To get past a "what you have" system, you need some sort of "token," such as an identity card with a magnetic strip. A "what you know" system requires you to enter a password or PIN number. A "who you are" system is actually looking for physical evidence that you are who you say you are -- a specific fingerprint, voice or iris pattern. "Who you are" systems like fingerprint scanners have a number of advantages over other systems. To name few: Physical attributes are much harder to fake than identity cards. You can't guess a fingerprint pattern like you can guess a password. You can't misplace your fingerprints, irises or voice like you can misplace an access card. You can't forget your fingerprints like you can for…
Analysis In movies and TV shows, automated fingerprint analyzers typically overlay various fingerprint images to find a match. In actuality, this isn't a particularly practical way to compare fingerprints. Smudging can make two images of the same print look pretty different, so you're rarely going to get a perfect image overlay. Additionally, using the entire fingerprint image in comparative analysis uses a lot of processing power, and it also makes it easier for somebody to steal the print data. Instead, most fingerprint scanner systems compare specific features of the fingerprint, generally known as minutiae. Typically, human and computer investigators concentrate on points where ridge lines end or where one ridge splits into two (bifurcations). Collectively, these and other distinctive features are sometimes called typica. The scanner system software uses highly complex algorithms to recognize and analyze these minutiae. The basic idea is to measure the relat…
Capacitance Scanner Like optical scanners, capacitive fingerprint scanners generate an image of the ridges and valleys that make up a fingerprint. But instead of sensing the print using light, the capacitors use electrical current. The diagram below shows a simple capacitive sensor. The sensor is made up of one or more semiconductor chips containing an array of tiny cells. Each cell includes two conductor plates, covered with an insulating layer. The cells are tiny -- smaller than the width of one ridge on a finger.
The sensor is connected to an integrator, an electrical circuit built around an inverting operational amplifier. The inverting amplifier is a complex semiconductor device, made up of a number of transistors, resistors and capacitors. The details of its operation would fill an entire article by itself, but here we can get a general sense of what it does in a capacitance scanner. (Check out this page on operational amplifiers for a technical overview.) Like any a…
Optical Scanner A fingerprint scanner system has two basic jobs -- it needs to get an image of your finger, and it needs to determine whether the pattern of ridges and valleys in this image matches the pattern of ridges and valleys in pre-scanned images. There are a number of different ways to get an image of somebody's finger. The most common methods today are optical scanning and capacitance scanning. Both types come up with the same sort of image, but they go about it in completely different ways. The heart of an optical scanner is a charge coupled device (CCD), the same light sensor system used in digital cameras and camcorders. A CCD is simply an array of light-sensitive diodes called photosites, which generate an electrical signal in response to light photons. Each photosite records a pixel, a tiny dot representing the light that hit that spot. Collectively, the light and dark pixels form an image of the scanned scene (a finger, for example). Typically, an analog-…

FINGERPRINT BASICS

Fingerprints are one of those bizarre twists of nature. Human beings happen to have built-in, easily accessible identity cards. You have a unique design, which represents you alone, literally at your fingertips. How did this happen? People have tiny ridges of skin on their fingers because this particular adaptation was extremely advantageous to the ancestors of the human species. The pattern of ridges and "valleys" on fingers make it easier for the hands to grip things, in the same way a rubber tread pattern helps a tire grip the road.
The other function of fingerprints is a total coincidence. Like everything in the human body, these ridges form through a combination of genetic and environmental factors. The genetic code in DNA gives general orders on the way skin should form in a developing fetus, but the specific way it forms is a result of random events. The exact position of the fetus in the womb at a particular moment and the exact composition and density…

HOW FINGERPRINT SCANNER WORKS

Photo courtesy Siemens
A computer mouse with a built-in fingerprint scanner
Computerized fingerprint scanners have been a mainstay of spy thrillers for decades, but up until recently, they were pretty exotic technology in the real world. In the past few years, however, scanners have started popping up all over the place -- in police stations, high-security buildings and even on PC keyboards. You can pick up a personal USB fingerprint scanner for less than $100, and just like that, your computer's guarded by high-tech biometrics. Instead of, or in addition to, a password, you need your distinctive print to gain access. In this article, we'll examine the secrets behind this exciting development in law enforcement and identity security. We'll also see how fingerprint scanner security systems stack up to conventional password and identity card systems, and find out how they can fail.

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