—- Update 9/17/2012 —-
To clarify some recent confusion — “dynamic stripe” technology, as described in this article, is not in reference to any property of Dynamics, Inc. Dynamic stripe technology is a generic term of art, by which the author simply means to refer to a commonly employed means of implementing a reprogrammable magnetic stripe.
To learn more about the history of this technology, check out our article on the topic!
Powered cards are the next generation of credit cards and security cards. These “smart” cards may contain embedded battery power, memory, and microprocessors, and can be used as One Time Password (OTP) cards, financial cards, and dynamic-stripe cards to name a few. Dynamic-stripe cards are able to emulate any other magnetic-stripe and can be used to put multiple sets of stripe data on a single card as has been demonstrated by Dynamics inc.
First, it is essential to understand how data is stored on the traditional cards in your wallet.
The stripe on the back of a credit card is a magnetic stripe, often called a magstripe. A magstripe is similar to a piece of cassette tape. It consists of tiny, iron-based(rust) magnetic particles coated in a hardened, plastic film-like epoxy. Each of these particles is a bar magnet measuring 20 millionths of an inch in length. When the magstripe is “written”, the tiny bar magnets are magnetized in either a north or south pole direction.
Card Data Formatting
Cards are required to comply with ISO 7810 standards, which define the required specifications for Magnetic Cards to ensure cross-compatibility between cards and card-readers across the world. ISO 7810 standards dictate card size, thickness, and magstripe encoding.
Contained within the visible stripe are three smaller and separate .110-inch-wide “tracks.” The three track design allows more data to be stored in a magstripe card.
Track 1 (IATA)
Zeros | Start Signal | Primary Acct (19 characters max) | Name (26 characters max) | other data | End Signal | zeros
Named after the “International Air Transport Association,” Track 1 contains the cardholder’s name and account number in addition to other discretionary data. This track is sometimes used by the airlines when a traveler secures reservations with a credit card. The traveler’s name just “pops up” on a ticket machine with the swipe of a credit card!
Track 2 (ABA)
Zeros | Start Signal | Primary Acct (19 characters max) | other data | End Signal | zeros
Standardized by the “American Banking Association,” track 2 is read by ATMs and most payment terminals. Track 2 contains cardholder account number, an encrypted PIN, and other discretionary data.
Track 3 (Thrift)
There are too many non-standard uses of Track 3 to enumerate. Suffice it to say, track 3 is largely an abandoned track and consequently is only used in select scenarios.
When a card is swiped through a card reader, an analog signal is created. This analog signal can be converted to a digital signal the POS (Point Of Sales) system can then accept and process.
Now onto powered cards with dynamic stripes
First off, powered cards such as the cards manufactured by Dynamics Inc. are completely different beasts compared to traditional magstripe cards. They contain a significant amount of electronics, a battery, and they manage to pack all of this inside of a normal looking and standard size plastic card.
Remember wrapping wire around a nail in school to make an electromagnet?
Dynamic stripe powered cards work similarly, and contain small coils encapsulated within a plastic card body. Signals can be sent to the coils from a small microcontroller also embedded within the body of the card.
The magnetic fields produced from these signals traveling through the coils can effectively spoof or emulate the signal that a card reader would see from a traditional credit card.
All this technology needs to be powered, so Lithium ion thin film batteries are embedded within the plastic of the card. These batteries may need to survive a hot lamination encapsulation process so the battery must be able to take the heat without degradation. Many of the powered cards out there rely on thin-film batteries from Solicore Inc out of Lakeland, FL.
When the card is swiped, internal read head detector coils sense movement passed the read head by the hall effect and proceeds to send a signal to the microcontroller; this awakens the microcontroller turning it on. The microcontroller then sends the card data that was stored in the memory to the emulator coils.
The signal may be amplified if needed before it is sent through the emulator coils. The microcontroller can send the stripe one and two data through both coils simultaneously so both tracks can be emulated. The data is also “played” or sent through the emulating coils in a time short enough to allow all the data to be sent before the card leaves the reader.
The emulator coils can be wrapped around an electromagnetically inducible material, (e.g., permalloy, iron, steel, ferrite, nickel alloy), or any a soft magnetic material.
Soft magnetic materials are notable for having very high magnetic permeability, 100-1000x higher than that of steel. In other words, a soft magnetic material has the ability to magnifiy magnetic fields in coils many thousands of times.
Any increase in the performance of the transducer, decreases current needed, and increases the overall efficiency of the powered card, allowing for longer life.
If you are interesting in learning more in this area, feel free to contact me at firstname.lastname@example.org