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An introduction to the Java Ring

Learn about the inner workings of this secure, durable, wearable Java-powered electronic token

By Stephen M. Curry, JavaWorld.com, 04/01/98

This month's column is split into two parts. The first part, embodied in this article, offers the history of the Java Ring and the technology used to build it, as well as a brief discussion of the suitability of the iButton for security applications and other applications. The second part, demonstrates how to use the Java Card 2.0 API with the Java iButton and provides the reader with a very early look at how to design an application, download it, and then communicate with an application running on a Java Card.

It's in the details

The Java Ring is an extremely secure Java-powered electronic token with a continuously running, unalterable realtime clock and rugged packaging, suitable for many applications. The jewel of the Java Ring is the Java iButton -- a one-million transistor, single-chip trusted microcomputer with a powerful Java virtual machine (JVM) housed in a rugged and secure stainless-steel case. Designed to be fully compatible with the Java Card 2.0 standard (for more on Java Card 2.0, see last month's Java Developer column, "Understanding Java Card 2.0 ") the processor features a high-speed 1024-bit modular exponentiator for RSA encryption, large RAM and ROM memory capacity, and an unalterable realtime clock. The packaged module has only a single electrical contact and a ground return, conforming to the specifications of the Dallas Semiconductor 1-Wire bus. Lithium-backed non-volatile SRAM offers high read/write speed and unparalleled tamper resistance through near-instantaneous clearing of all memory when tempering is detected, a feature known as rapid zeroization. Data integrity and clock function are maintained for more than 10 years. The 16-millimeter diameter stainless steel enclosure accommodates the larger chip sizes needed for up to 128 kilobytes of high-speed nonvolatile static RAM. The small and extremely rugged packaging of the module allows it to attach to the accessory of your choice to match individual lifestyles, such as a key fob, wallet, watch, necklace, bracelet, or finger ring.

Historical background

In the summer of 1989, Dallas Semiconductor Corp. produced the first stainless-steel-encapsulated memory devices utilizing the Dallas Semiconductor 1-Wire communication protocol. By 1990, this protocol had been refined and employed in a variety of self-contained memory devices. Originally called "touch memory" devices, they were later renamed "iButtons." Packaged like batteries, iButtons have only a single active electrical contact on the top surface, with the stainless steel shell serving as ground.

Data can be read from or written to the memory serially through a simple and inexpensive RS232C serial port adapter, which also supplies the power required to perform the I/O. The iButton memory can be read or written with a momentary contact to the "Blue Dot" receptor provided by the adapter. When not connected to the serial port adapter, memory data is maintained in non-volatile random access memory (NVRAM) by a lifetime lithium energy supply that will maintain the memory content for at least 10 years. Unlike electrically erasable programmable read-only memory (EEPROM), the NVRAM iButton memory can be erased and rewritten as often as necessary without wearing out. It can also be erased or rewritten at the high speeds typical of complementary metal oxide semiconductor (CMOS) memory, without requiring the time-consuming programming of EEPROM.

 

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