Communications

Method
Standards
Type of Memory
Memory Capacity
Memory Integrity

Lifespan
Power Requirements
Security
Environmental
Reliability

General Description of Components
Standard Configuration
Physical Characteristics
Standard Interfaces

Initial Equipment
Infrastructure
Operational

Anticipated Developments
Theoretical Technical Limitations
Standards

Magnetic stripe media provides an inexpensive and flexible means of maintaining modifiable information.

A magnetic stripe consists of magnetic material combined with paint or binder that is subjected to a magnetic field before drying. This field aligns the magnetic poles of the magnetic material, and makes it suitable for reading and writing. The magnetic stripe may be stamped or laminated on any flat surface, such as a credit card, a hotel room card-key, or a security identification badge. The information is written on and read from the stripe by a number of types of readers. A reader consists of a magnetic recording head which can read and write the magnetic information on the card. The information on the card consists of binary code. From this low level data form, a high level data format such as ISO BCD or ALPHA is used to convert the binary code into alphanumeric characters.

Magnetic stripe cards started to appear in the banking industry in the late 1970s. Once international standards were developed, magnetic stripe cards became an effective way of providing convenient customer service. The use of ATMs allowed the banks to offer new services, and to accommodate the growing number of customers without having to increase staff levels or build expensive facilities.

Today magnetic stripe cards are widely used for banking, retail, telephone systems, access control, airline ticketing, and transit fare collection. In fact, the existing infrastructure of magnetic stripe reading and writing equipment is so extensive that changing to an alternate technology would likely be a very slow and costly process.

Card Performance Characteristics

The magnetic stripe and reader communicate via a magnetic field. Reading is performed by swiping the magnetic stripe card across through a reader. The reader picks up the changes in polarity on the stripe through the magnetic recording head. For writing, the reader creates a magnetic field that will effectively alter the polarization of a small region on the stripe, and thereby write information on the stripe. Data interchange between the card and the read/write unit typically occurs at speeds of about 12,000 bits per second.

There are several parameters associated with magnetic stripes such as the physical attributes of the media, location of tracks on the stripe, encoding techniques, decoding techniques, and data format.

ISO has two specifications for these parameters [ISO ALPHA and ISO Tracks 1, 2, and 3] but many applications do not adhere to them. This lack of adherence is due to the flexibility of available equipment, as well as a desire to enhance security.

Read/Write-When a stripe is exposed to a polarized magnetic field, it will adopt a similar field for a small specific region on the stripe. This process can be repeated for erasing data or storing new data.

The capacity of a specific magnetic stripe is determined by the type of media, the method of writing the data, the number of tracks, and the density of the information on the tracks. The ISO standard card consists of three tracks. Track 1 was originally created for the airline industry and can hold up to 79 alphanumeric characters using a density of 210 bits per inch. Track 2 is used by the banking industry and can hold up to 40 numeric characters using a density of 75 bits per inch. This track is generally encoded before the card is given to the end-user. Track 3 is the area most commonly used for information that changes frequently. This track holds up to 107 numeric characters using a density of 210 bits per inch. Combining the memory capacities of tracks 1, 2, and 3, the ISO standard card can hold up to 226 alphanumeric characters.

The magnetic stripe is susceptible to alteration or erasure from other magnetic fields, as well as physical damage and environmental damage. The need to prevent damage to the information maintained on the stripe as a result of inadvertent contact with magnetic fields that may be encountered in day-to-day use of a card has led many manufacturers, integrators, and application engineers to develop cards with more resistant magnetic properties. The resistance of the magnetic stripe is typically discussed in terms of coercivity [measured in Oersteds], which is defined as the magnetic force required to erase an encoded tape. Generally, low coercivity cards [300 Oersteds] are more easily changed or encoded than high coercivity cards [3000 Oersteds]. There are limitations to useful coercivity levels, however, since a stripe with a coercivity above 3000-5000 Oersteds may be difficult for the read/write to modify.

Additionally, some manufacturers have stated that coercivity may not be the best indicator of stripe performance, and have started to consider more performance oriented measures of magnetic immunity.

The life span may vary significantly due to the quality of reader, material used in the card, and the environment in which the card and the read/write equipment are kept and operated. In many cases the card will be physically damaged before the magnetic integrity of the stripe becomes a factor.

Some manufacturers claim that typical readers will read two million cards and that the typical card can maintain its magnetic integrity through several thousand reads. However, practical experience has shown that most regularly used card will wear out and will need to be replaced after about 1000 reads.

Obviously, this number would be significantly lower for thin paper magnetic stripe cards that are easily damaged.

There are no on-card power requirements.

There are numerous ways of violating the security of a magnetic stripe card including counterfeiting, skimming, and buffering. Presently, the manufacture of counterfeit cards is a significant security problem. However, skimming, or encoding additional data on a card, and buffering which involves the temporary storage and subsequent reloading of original data, can be prevented through measures taken by some available products. For example, some vendors offer products that combine unique security signatures, or signals, with natural variations, or "jitter", when the cards are encoded, to deter counterfeiting or alteration of stored information.

The best environment for magnetic stripes is a cool, dry, clean area. The typical storage temperatures are -40 to 176 øF [-40 to 80 øC]. Typical operating temperatures are 32 to 130 øF [0 to 55 øC]. Operational relative humidity is 5% to 95% non-condensing. Magnetic fields may alter or erase information stored on the stripe or may reduce the performance of the stripe. Dirt of any kind that collects on the magnetic stripe may cause substantial wear, or impede the reading or encoding operation of the read/write unit.

The reader head is designed to be in direct, physical contact with the magnetic stripe. Any dirt, chemicals or grime which interferes with this contact will degrade performance significantly. Studies have shown that common magnetic stripe cards have an read failure rate of 0.06%.

System Operations

Magnetic stripe cards are generally ISO standard thickness or thinner. The materials include PVC, polyester, paper, and other similar materials. The weight of the card is determined by the material used, but the choice of card design is usually based on the specific application, the desired price per card, and the desired minimum lifetime of the card.

The standard system configuration includes a magnetic stripe card, a read/write unit, and a data analysis platform. These components each come in several types, and there are several thousand different configurations possible. Each application may have a unique configuration.

The size and thickness of magnetic stripe cards vary depending on the type of paper or plastic that is used. A wide variety of read/write units are available; their size depends on the intended application.

Some read/write units are completely stand-alone and may house data storage equipment for later upload to a central facility. Small read-only units are also available and are relatively inexpensive.

Most magnetic stripe cards use variations of ISO BCD, ISO ALPHA and ISO Tracks 1, 2, and 3 standards. Many applications use slightly different formats for security reasons. The reader to controller interface is quite varied. The most frequent are RS-232 and RS-424.

Costs

Cards-Magnetic stripe cards are commodity priced. The typical card is purchased in large quantities [thousands] for pennies a card [on average $0.12-0.45].

Readers - The cost for a reader ranges from $200-600 [Point Of Sale reader} to several thousand [high quality reader/writer]. Read-only readers are also available for approximately $15-250.

Control Units - Control units are available for many applications and can be a personal computer. The costs range from a thousand dollars up to several thousand dollars.

The infrastructure cost would include cost of each reader/writer and control unit, inventory of blank cards, communications between control units and central system, and staffing to install, maintain, and man the control units.

Once the infrastructure is in place, the operational costs might include telecommunications costs, card distribution, customer service, and user account management.

Maintenance
While the cost of magnetic stripe cards and readers is inexpensive in comparison to other card technologies, the maintenance costs could be rather substantial. Due to the insert or swipe nature of card reading and the mechanical nature of the read/write units, the systems are often prone to failure. Transport type read/write units can have an especially high maintenance component. Swipe read/write units have fewer mechanical parts, but are still susceptible to wearing and misalignment of the magnetic heads, and vandalism of the slot. Consequently, a significant level of staffing will be required to repair or replace equipment, maintain spare parts, and monitor system usage.

Future Trends and Considerations

No significant developments are anticipated, but minor advances may be made in card security as the result of new or enhanced security procedures.

Many aspects of magnetic stripe technology appear to be nearing theoretical or practical limitations. For example, the memory capacity of an ISO standard card is approximately 1 kbits, and although more information could probably be stored on a card, a significantly different configuration would make the card unreadable to an ISO standard reader.

Reasonable advances may still be possible in the area of security, but staying one step ahead of counterfeiting or fraud has not been an easy task for the banking industry over the last few years.

Standards already exist [ISO] for the placement of information on the stripe as well as the formatting methods. Since most applications do not adhere to the specifications exactly [due to the flexibility of the equipment and the desire for increased security], there may be minor changes to the existing standards to reflect this variation in the marketplace.