Near Field Communication Primer

I thought I’d do a primer about NFC since Samsung’s Galaxy Nexus is getting a lot of press about it. You may have heard of Google Wallet or how NFC is going to be built into smart phones in the future. Maybe you haven’t thought about how it works or how to hack it. As a side[side(side)] project I’ve been working on NFC research with (as always for me) a specific focus on the security perspectives. This is an overview of NFC to maybe peak your interest.


Near Field Communication is a way to transmit information between intelligent devices. I know you’re already thinking Bluetooth but wait. NFC has a limitation that says in its spec that it can’t be more than .2m away from its partner during communication. It may be a bit more depending on the implementation but the thing to remember here is that the protocol itself is what limits the distance, not just the hardware. (Quit pointing that gigantic antenna at my pocket right now!) It transmits on the HF band 13.56MHz, a frequency already used by some RFID chips and fun devices like the Proxmark 3.


Here’s what’s different about NFC: There are three different modes.

  • Reader/Writer: Commonly used in smart posters or smart stickers. Think QR code but subtle.
  • Peer to Peer: Data is exchanged back and forth between devices; securely exchange credit cards, give your friend your home WIFI settings, or exchange business cards.
  • Card Emulation: A device acts like a contactless smart card. What if you could use your phone as a bus pass instead of keeping that flimsy magstripe pass in your pocket?


Lets take care of that up front. NFC sounds a lot like RFID (they share the whole RF thing) and it seems to get stored in people’s heads that way because NFC has the card emulation mode where it emulates at “tag” or an RFID chip.  RFID isn’t usually much more than a tag blindly broadcasting data hoping a receiver picks it up. Passive tags (or little antennas without a power source) sit and wait for an RFID reader to come by to energize them. They get all excited and tell the reader everything they know. Imagine a dog just waiting at the door for it’s owner to come home. The active RFID tags have a battery in them that constantly broadcasts itself to anyone that will listen. Kind of like that annoying friend you have that tells you everything about their life even though you never asked. NFC on the other hand is like an intelligent college student. She can have an intimate conversation with you, she can make a presentation in front of a class, but she can still get drunk and act stupid if that’s what everyone else is doing at the party.

NFC is not a new technology

We’ve seen them in European phones since 2003 or 4 and they’ve been hacked on for just as long. The folks at the Chaos Computer Club have been hacking on NFC since it’s original inception; when manufacturers like Nokia started installing it into their feature phones, AKA dumb phones. It never made it across the water – some may say due to some FCC regulations on the 13.56 frequency but I’ll leave that topic to the Ham guys.


If you haven’t already, you should put on your tin foil hat now. NFC is a way for corporations to take over our bodies, man! Well…most likely not. But you’re already thinking about the security problems as soon as I wrote “credit card.” I’m going to save this whole discussion for another day but the tl;dr version is that NFC has been designed with security in mind but a lot is left up to the developer to implement securely. We all know how well that works especially for mobile app developers so I’m sure everything is going to be fine, right? Maybe next time I’ll tell you about the butt sniffing attack. No seriously.

Android and The Galaxy Nexus

How is Android implementing NFC in the Galaxy Nexus? Here’s an example of a peer to peer mode connection: When you put a Galaxy Nexus next to another Galaxy Nexus, the phone will make an NFC connection as long as both phones are unlocked. If the app that you  have open supports NFC (i.e. Google Maps) it will allow you to communicate data from your app to the other device. Some examples of this are sharing contact information, location data, websites, etc but apparently it’s going to be used for games or whatever developers can think of.

The Reader/Writer mode will allow you to take an NFC tag and shove it next to the phone. Depending on the data stored on the card, it will open an appropriate app to view the content. In the case of an NFC tag that is contains a URL, it will automatically go to that page. Ask me about some of the NFC tags I’ve made at a 2600 meeting sometime. :)

More info:

If you want to see a much better post that’s chock full of info check this out:

Here’ s a random YouTube video of two guys with Galaxy Nexuses so I don’t have to make one:

from on December 21st, 2011Comments0 Comments

Chatting With Spain

Last Thursday’s Do night, JustBill brought in his HF rig to try out on our club antennas.  Bill is an expert user on several digital communications modes including PSK31.  PSK31 or “Phase Shift Keying, 31 Baud” is a digital radio modulation mode, used primarily in the amateur radio field to conduct real-time keyboard-to-keyboard informal text chat between amateur radio operators.  After we got his rig set up and interfaced to Ham Radio Deluxe running on the club computer, we started a session on 40 meters and keyboard chatted with a guy in Spain.  We also chatted with a Ham in Wisconsin and another in Alabama.  We heard a Russian station but not quite enough signal to get to him with 50 watts.  Here’s a link to a wiki on PSK31:

JustBill at the controls….with aliens supervising

We also got an old Radio Shack HTX-202 operating APRS (Automatic Packet Reporting System) with UI-View32 (an ancient client software for radio packet hosting) and the ProComm TNC to communicate to the radio.  K2HAX is on the map!  APRS is an important tool for position reporting, remote telemetry, text messaging anyone anyplace, and local coordination of emergency training events. For a cool view of current APRS activity around K2HAX, go here.


’73 – N2ZVP – rochbert

from on December 13th, 2011Comments0 Comments

K2HAX Is On The Air

K2HAX is on the air!  With our move to the new space, we have access to the roof.  On a beautiful fall day, Chris Olin and I put up a 30’ fiberglass mast on a tripod base (not attached to the roof).  Then we hoisted up a trapped dipole for 10-80 meters and a G5RV.  The dipole is oriented SW-NE, the G5RV is SE-NW.  We also put up a 2m/70 cm J-Pole for VHF/UHF.  All the feedlines were run with previously used 8/U down to our space (about 150’) and into the Ham Shack.

We initially had a Kenwood TS-530s transceiver and roller tuner setup for HF and we made a few contacts.  We wanted to get the Yaesu FT-857GX out of the storage container and try it out.  That is setup now along with an automatic tuner.  Reception seems decent.  We are waiting on an operable microphone to get back on the air.  Bill, Von, Rowan, and Steve are working on that.  We will be working on CAT control and a hook-up for using SDR like functionality with Ham Radio Deluxe, allowing us to get into the digital communication modes.

The Yaesu FT-8800 VHF/UHF rig is working well, K2HAX normally monitors 146.61 (N2MPE local ARES/RACES repeater) while someone is in the shack.  We have cables for programming this rig on order and also have a cable for use with the PacComm TNC for packet, etc.

We also have a desktop PC with a nice monitor setup for use with the transceivers.  We are waiting on a 2 port serial card to communicate with the radios.  The remote programming of the radios and the option for digital mode communications (PSK, Packet, etc) opens up with the PC.

Our bench includes power supplies, frequency counters, various multi-meters and hand tools.  We have a great selection of soldering tools for discrete and SMT component work.  We have a variable temperature iron and a variable speed and temperature blower for re-work.  On order is a Hakko 808 de-soldering tool.  We have 2 antenna analyzers, a new Comet and an older MFJ.  Several bench projects are already underway including Jamie’s whispering clocks, many cable hacks for the radios, and Walter’s attempts to repair blown audio equipment.

Ham radio is witnessing a rebirth in popularity.  Emergency preparedness at the county/state/and national level has recognized the value of Ham radio as the most dependable means for communication during an emergency.  Interlock members have participated in local POD drills, Ginna nuclear event practice response teams and are regular attendees at the local ARES/RACES meetings.  Ham Radio can provide texting, TV and many other familiar forms of communication without any annoying infrastructure.  We can DX with Ham operators around the world, by voice and many new and old digital modes.  SDR is an emerging technology applied to Ham radio; opening up some fantastic possibilities for low power operation, contesting, and pulling weak signals out of the noise.

Ham radio is growing in popularity.  Interlock Hams would love to introduce anyone interested to the hobby and answer any questions you may have.

’73 Walter

Hammy ShackThe Ham Shack

from on November 27th, 2011Comments0 Comments