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Keeping It Private: Blocking RFID Readers from Reading your ID Card

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If you've ever watched an adult pay for something by simply touching their credit card to a machine at a store, or you've done the same with a bus pass, you've seen an RFID tag in action. An RFID (Radio-Frequency IDentification) tag allows a card to be read by a computer from a short distance away. This is very convenient, but it also allows criminals to steal information about you. For instance, on the subway or the bus, someone standing next to you can use an RFID reader to access the data on that card. After learning what materials can be used to block an RFID reader, you can design a solution to protect your cards and your passport.


Areas of Science
Time Required
Short (2-5 days)
Material Availability
This science project requires an RFID reader and RFID tags. See the Materials and Equipment list for details.
Average ($40 - $80)
No issues

Howard Eglowstein, Science Buddies

  • Microsoft Windows® is a registered trademark of Microsoft Corporation.
  • Macintosh®, Mac® and 'OS X'® are registered trademarks of Apple, Inc.
  • Apple® is a registered trademark of Apple, Inc.
  • Linux® is a registered trademark of Linus Torvalds.
  • E-ZPass® is a registered trademark of the Port Authority of New York and New Jersey
  • FasTrak® is a registered trademark of Bay Area FasTrak.
  • Hyperteminal® is a registered trademark of Hilgraeve, Inc.
  • PuTTY is copyright 1997-2014 by Simon Tatham
  • SerialTools is copyright 2013 by Erwin Bejsta


To demonstrate that simple materials can be used to protect an RFID tag or card from being read by an RFID reader.


Do you ride a bus to school and simply wave your card past a pad to get on the bus? Your school may have given you an ID card that you can simply wave at a special pad as you come in the door. Maybe that same card is swiped over a pad in the cafeteria to get you a hot lunch. One of the adults in your life might need an ID card for work that they scan past a reader to access their office. Or they might have a passport that a border guard can quickly scan at the airport. Can they simply wave their credit card at the counter in the gas station convenience store to pay for a cold drink? In all of these cases, the card or passport uses Radio Frequency IDentification (RFID) technology to allow quick and convenient access to personal information. Unlike magnetic stripe cards, RFID cards let a computer use the information without touching the card.

RFID is also around us in other applications. We put microchips under the skin of our pets to help veterinarians identify them if they become lost and lose their collars. Your family car might have a toll-paying system transponder on the windshield (known in much of the United States as E-ZPass®, I-PASS, or FasTrak®). If your family has one of those on your car, you can get through the toll booth without stopping; in some cases, you whiz past at 60 mph while others have to stop and pay. Very convenient. But when your personal ID contains RFID for convenience, you might not always want it to be read so easily.

Let us look at how RFID systems work, and how you can use that knowledge to improve privacy and security to better safeguard your personal information. An RFID tag is a miniature radio station. It has a radio transmitter connected to a computer chip and when asked, will turn on the transmitter and broadcast the data that it has. That may sound like how your cell phone works, for example, but there is a huge difference. Your cell phone has a battery that has to be kept charged and it can transmit data for many kilometers. An RFID tag has no battery that you have to charge (a passive RFID tag has no power source at all, while an active RFID tag has a small battery used only when responding) and can't transmit very far. In addition to the computer chip and radio transmitter, the RFID tag also has energy-harvesting parts. How do these work? Well, a coil antenna is tuned to a specific frequency. When the reader wants to get information from the tag, it sends out a signal at the tag's specific frequency. The energy from the radio signal is converted to just enough power to start up the computer chip, energize the radio transmitter in the tag, and send back the tag's data. The reader gets the signal back, extracts the data it needs, and turns off. The tag is now unpowered and goes dead until the next read. The advantage? Very inexpensive and zero maintenance.

Another way of looking at it is that you have a good friend who knows just about everything. You are working a math problem and you really need to know the value of the constant π (Pi). You find your friend in the backyard after a long morning of studying and she is sound asleep. You call her name, but nothing will wake her up. Then you remember that she loves apples. You happen to have an apple, so you offer it to her if she will wake up and answer your question. As soon as you offer the treat, she wakes up, gives you the answer you needed (3.14159...), and goes back to sleep.

Three panel comic of a sleeping woman waking up to answer a question for an apple

Drawing of a 3 panel comic strip explains how an RFID chip works. In the first panel of the comic a sleeping woman represents an RFID chip. In the second panel, another person walks up to the woman and offers her an apple if she can recite the value of pi. The woman recites the value of pi and goes back to sleep in the last panel. The apple represents an incentive or trigger that the RFID chip needs before displaying any information.

Figure 1. An RFID tag is like a friend who knows something important, but won't tell you unless you get her attention with an energy-rich snack.

Now you are ready to get started. In this science project, you will learn what materials can be used to block a radio-frequency identification (RFID) reader, and design a solution to protect your ID cards and passport.

Terms and Concepts



Materials and Equipment

Important: the Parallax USB RFID reader linked below is no longer available. You will need to find a different RFID reader to do this project and follow the instructions for your reader. Alternatively, you may be able to purchase a used Parallax reader or find one from another vendor if you search online.

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Experimental Procedure

Important: the instructions below were written for the Parallax USB RFID reader, which is no longer available. You will need to follow the instructions for your RFID reader if you purchase a different one.

Gathering Your Materials

In this science project, you will look at what materials can be used to keep an RFID reader from reading an RFID tag. Different types of RFID systems will be more or less easily blocked by different materials, but metals are generally a good bet.

Aluminum tape, wire mesh and cake pan next to a steel pan, copper scrubbers, RFID shield, usb cable and RFID reader kit
Figure 2. Suggested materials and the RFID reader. Back row: aluminum tape, one type of commercial RFID shield, a USB cable, and the Parallax RFID reader kit (containing the reader itself and four different type of compatible tags). Front row: Steel baking pan, aluminum mesh (lint trap), copper pot scrubbers, and an aluminum cake pan. Good candidates would also include aluminum foil, copper foil, aluminum window screen, and copper mesh (not shown).

You should try a variety of materials in a variety of configurations:

  • In the aluminum family, try aluminum foil sheets and aluminum baking pans. In addition, aluminum tape is used by heating contractors to seal up joints when they install and repair hot-air heating systems.
  • Copper might be a little harder to find, but you can find copper foil and copper tape at a specialty shop that sells materials for working with stained glass, or online. Copper mesh is sold specifically for electronic shielding (look up "Faraday cage") and is available online.
  • Steel baking pans might be in your kitchen already. For another configuration, a local metal shop might have some steel scraps you can have. Explain that it is for science and they might be impressed enough to give you a hunk.

Installing the Software


Notes: Depending on who owns the computer you are using, get permission from your parents or your school before you download and install any software. The exact procedure for installing software on your particular computer may vary depending on how that computer is set up. If you need to, ask an adult for help installing the drivers and application software.

  1. The RFID reader in the materials list will be connected to your computer via USB. That is very common, of course, but an RFID reader is not like a keyboard or a mouse; the computer will not know what to do with the data. To fix that, you need a device driver, which allows the computer to know how to access data from the reader.
  2. In the RFID kit, you will find instructions for going to the Parallax website for documentation, and to the FTDI website for drivers. The RFID reader uses chips from FTDI, so it is necessary to have the drivers from their site that are specific to your computer. Drivers are available on their website for Windows XP, Vista, Windows 7 and Windows 8, and for Mac® OS X 10.6 or later. Linux systems may not need drivers, as many Linux installations already support the FTDI chipset.
  3. The goal is to make the RFID reader look like a standard serial communications port. Follow the instructions provided with the kit and on the Internet to get the drivers installed. Ask an adult if you need assistance.

Serial Terminal Emulator

Here is a little background about the terms serial and terminal. It is somewhat "old school" to keep referring to "serial" and "terminals" on modern computers, but the terms go back decades (to the 1960s and 1970s) when a computer did not have a display or a keyboard. Instead, computers used a different type of port, called a serial port, which was common before USB was invented. The computer may have been in a special air-conditioned room nearby, while the user had a terminal on his or her desk that had the display and the keyboard. So we still use that terminology today when we talk about how a computer communicates with other devices, even though there is no separate terminal on most people's computers, and many computers no longer have the old standard serial port.

In this science project, you will need to look at the data coming from the RFID reader. Because of the driver you installed in the previous section, your computer will think the data is coming in on a serial port. To see the data, you need to install a program that works like an old-style terminal to display the raw data. These terminal emulators are easily found for just about any computer you will be using.

  • On Windows, your computer may already have Hyperterminal installed.
  • Newer Windows systems may not have Hyperterminal installed, but you can download a free program called PuTTY (the name evokes even older technology) that will do the job perfectly and is actually preferred for this project.
  • Under Mac OS X, look in the app store for a program called SerialTools.
  • Linux machines can use a serial terminal emulator such as minicom.

Connecting the RFID Reader

  1. With the device driver and terminal emulator installed, plug the RFID reader into the computer using the mini USB cable. Depending on your computer, it may take a moment or two for the computer to recognize the device. It will appear in your computer as a serial port.
    1. On Windows, it is a device that is usually named something like 'COM4', 'COM5', or some other number. Figures 3 and 4, below, show some sample screens from Hyperterminal and PuTTY (preferred) that you might run on a Windows computer. If using PuTTY, select the options as shown in Figure 4, using whatever COM port is correct for your particular installation.
    2. On a Mac or Linux machine, it could be named almost anything, depending on the specifics. That's okay though, as the serial terminal software can find it. Figures 5 and 6, below, show a successful setup using SerialTools, a program available for Mac OS X machines.
      1. Be sure to check the 'RTS' and 'DTR' boxes to activate the RFID reader, and click on "Connect."
      2. Once connected, SerialTools will display any data coming in from the RFID reader.
Screenshot of the program Hyperterminal recognizing a RFID reader that is plugged into a computer

Screenshot of the program Hyperterminal opening a window to attempt to connect to an RFID reader plugged into the computer. The connection window has COM10 selected as the connection method.

Figure 3. Hyperterminal is one program you may already have on a Windows computer. The RFID reader will appear as one of the higher-numbered COM ports.

Screenshot of a settings configuration window in the program PuTTY

Screenshot of a setting configuration window open in the program PuTTY. In the session tab there is an option to attempt to connect to a peripheral device that is inserted into the computer with a serial connector. Other options for connection types, speed, and sessions are also available in the window. More settings and options are listed in a sidebar to the left of the window.

Figure 4. PuTTY is a very popular terminal emulator that runs on just about any version of Windows. It is a better choice than Hyperterminal if you have permission to install software on your computer. Select the options as shown, using whatever COM port is correct for your particular installation.

Screenshot of the program SerialTools recognizing a RFID reader that is plugged into a computer

Screenshot of the program SerialTools for MacOS detecting a device connected to the computer. A drop down menu that displays devices connected to the computer is open and a usb-serial device is selected. Options can be changed for baud rate, bits, parity, stop bits, RTS, DTR, CTS, DSR, cr/lf, raw and local echo.

Figure 5. SerialTools for Mac OS X will show you a list of serial ports it found on your computer. In this example, it thinks it found some Bluetooth serial ports as well, but we connected through USB, so select the one with USB in the name. Be sure to check the 'RTS' and 'DTR' boxes to activate the RFID reader, and click on 'Connect.'

Screenshot of the program SerialTools displaying incoming data from a RFID reader that is plugged into a computer

Screenshot of data being displayed from an RFID chip in the SerialTools program. When an RFID reader is connected to the SerialTools program data from the reader will be sent to a small window in the bottom of the program window. There is an option to disconnect on the right side of the program window.

Figure 6. Once connected, SerialTools will display any data coming in from the RFID reader.
  1. Start the terminal emulator software. In the software's menus, you will find a place to select the device. You probably do not have many serial devices connected, so it should be easy to locate the correct port. The RFID reader uses 2400 baud, 8 bits, no stop bits (you can look this up if you want to know what that means). Select these options in your communications software.
  2. To check if you got it right, take one of the tags that came with your RFID reader and wave it within a few centimeters of the reader. You should see a 10-digit number appear on the screen.
    1. If you do, that's awesome! You got the configuration right and are ready to proceed with the test.
    2. If not, you may need to restart the computer to get the driver activated, or you may have selected the wrong serial port in the terminal software. Is the LED on the reader lit? If not, check that you have a working cable and that you plugged the cable into a working USB port.
  3. The tags in this kit each contain a unique 10-digit identifier. It doesn't make any difference for this science project what the data is, but the fact that the reader can read and report it is what we care about. Imagine though, that you could use those unique numbers to identify which tag it just saw. How could you use that information? Farmers tag the ears of dairy cattle to help track the animals and to allow automated feeding systems to provide just the right amount of food for each animal. You could put a tag on your dog's collar and put a reader on your dog door to keep out strays. Does it make you think of a way to build a musical instrument? Use your imagination! Once you have completed your testing, find some fun ways of using the reader and the sample tags.

Setting Up the Test

  1. First, cover the work surface with a piece of cardboard to protect it.
  2. Place the RFID reader on the flat side of one of your bricks, blocks, or other sturdy non-metallic object of your choosing, and carefully tape it in place with the masking or painter's tape, or attach it with rubber bands. It is not going to move much anyway, so you do not need to use a lot of tape. See Figure 7, below.
    1. If you are using a brick, the surface is likely to be rough, so be careful not to scratch the RFID reader any more than necessary. You could put a piece of paper towel between the RFID reader and the brick to prevent scratches.
  3. Pick one of the tags from the kit and attach it to the other brick with the tape or rubber bands. Position it the same height as the center of the reader, and place the two bricks a short distance apart, as shown in Figure 7, below.
  4. You will see data appear in the program window on your computer. As long as the tag is close enough to the reader, you will see it appear repeatedly. This is a perfect time to collect some control data and start a table in your lab notebook.
An RFID tag and reader are taped to two bricks facing each other with a small space separating both
Figure 7. Position the RFID reader and tag on two bricks (or some other sturdy supports) and space them a short distance apart.
Blue hanging tag Material
Distance No shielding (control) Aluminum foil RFID wallet Copper scrubber Copper foil
__ cm (farthest-read distance) ?????
__ cm (closer) ?????
__ cm (a little closer still) ?????
Table 1. A sample table for collecting your data. Make one table for each tag type you test. For each material, indicate (with "yes" or "no") whether the reader can read the tag from that distance through the test material.
  1. With none of your test materials (no "shielding") between the bricks, start with the tag pretty far away, enough so that the reader can't read the unshielded tag. Slowly decrease the distance until the RFID reader is reading the tag. Mark that distance in your data table in your lab notebook. When you have found the minimum distance, there is no need to keep moving the tag closer. Reset it back to a little farther than the furthest successful distance when the RFID reader read the tag.


  1. Start with one material, perhaps aluminum foil. Cut a piece just big enough to cover the tag and record its measurements in your lab notebook. Fasten it over the tag with a rubber band and repeat the test from the previous section. Can you find a distance where the tag becomes readable? Is it significantly closer than with no aluminum foil? Take careful notes and measurements as you test, and keep track of all data in your lab notebook.
A sheet of aluminum foil is placed between an RFID tag and an RFID reader which are both taped to bricks
Figure 8. Testing with aluminum foil material.
  1. Continue testing with the same-sized (or as close as possible) pieces of at least six other materials.
  2. Repeat the same tests again with the different tag types from the kit. Make a new data table for each new type of tag. Record all results in your lab notebook. Can larger tags be read from further away than the smaller ones? In your research about how RFID tags work, did you see the reason why this might be true?
  3. Many science fairs require that you do multiple trials for each test that you do. For example, you may need to do three separate trials with aluminum foil and your first RFID tag, three trials with your second material, etc. If this is necessary for your science project, you should expand your data table to include room for three trials for each test.

Evaluating Your Results

  1. Make a bar graph, with material type on the horizontal line (x-axis) and the farthest distance at which the tag could be read on the vertical line (y-axis). Calculate an average distance if you did more than one trial for each material. You may want to make a separate graph for each tag you tested, or combine all the different tags into one graph.
  2. From your tests, what can you conclude about what kinds of materials will stop an RFID tag from being readable? If you were asked to design something to carry your school ID in that would stop it from being read on the bus (if your school issues RFID ID cards), what would be a good material to use? How would you design it? Consider making one and putting it in your science project display.
  3. In your research, you may have found that different RFID systems operate at different frequencies and have different properties. You probably discovered that the reading distance of the inexpensive reader you used in this science project wasn't very large. You may also have found that it can only read one tag at a time. A large commercial reader that you might find in a factory or a warehouse will operate at much farther distances and read hundreds of tags at the same time. The reader you tested is a low-frequency (125 kHz) RFID system. You may want to find some specifications of commercial readers and compare them to the one you tested with. Compare prices, too; yours likely cost about $50. One you might put on a forklift in a warehouse could cost several thousand dollars! When preparing your display board, consider including images of these 'real' RFID readers along with their capabilities. Even with the limited capability of the small reader you tested with, it is still pretty amazing and useful!
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  • Experiment with the size of the test materials. Does a larger piece protect the tag better than a smaller piece?
  • Perform your tests again with non-metallic substances. Do any of them affect the ability of the reader to read the tag?
  • Make a protective carrier of some kind to keep the tags from being read. Using what you learned about these materials, what can you come up with that is practical and still protective? Can you protect your ID card or your parents' credit cards?
  • Do you know some place that uses commercial RFID equipment that would let you run a few tests? Perhaps you can get access to a warehouse where they have RFID tag stickers on boxes. Bring along some of your test materials and see of they shield the commercial tags in the same way they worked with your low-frequency tags.
  • Ask a local veterinarian how the RFID tagging works in pets and see if they will let you try your shielding material with their reader and the tag that might be in your dog or cat. Those systems do not read from a large distance at all, but can they read through any of your test materials?
  • For another science project about RFID tags, try Sounds Like RFID: Using a Radio Frequency Identification (RFID) Reader to Make Musical Instruments


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MLA Style

Science Buddies Staff. "Keeping It Private: Blocking RFID Readers from Reading your ID Card." Science Buddies, 24 Dec. 2022, https://www.sciencebuddies.org/science-fair-projects/project-ideas/CompSci_p048/computer-science/blocking-rfid-readers-from-reading-your-id-card. Accessed 28 Nov. 2023.

APA Style

Science Buddies Staff. (2022, December 24). Keeping It Private: Blocking RFID Readers from Reading your ID Card. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/CompSci_p048/computer-science/blocking-rfid-readers-from-reading-your-id-card

Last edit date: 2022-12-24
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