Amtel® Corporation (San Jose, CA) offers the CryptoMemory® family of EEPROMs with a 64-bit embedded hardware encryption engine, four sets of non-readable 64-bit authentication keys, and four sets of non-readable 64-bit session encryption keys. The new devices provide a low-cost means of preventing product counterfeiting and/or piracy.

Each crypto memory chip contains a unique serial number and the user can optionally assign one of four unique 64-bit encryption keys to each zone. The host knows how to generate these keys using the serial number and a special "secret" that it stores. During mutual authentication, the CryptoMemory sends its serial number and encrypted identity to the host. The host then computes a 64-bit number, called a "challenge," based on a random number and its own encryption key. It sends the random number and the "challenge" to the device. The CryptoMemory device uses the random number and its own key to generate a 64-bit number. If the 64-bit number matches the "challenge," the CryptoMemory device accepts the host as authentic. The device then generates a new encrypted identity, which it sends to the host as a "challenge." The host uses the original encrypted identity of the device, the same random number it sent, and the device's serial number to compute a new encrypted identity. If that number matches the "challenge," the CryptoMemory is deemed to be authentic.

The authentication keys are generated by the host in a secure location. They are based on the CryptoMemory's serial number and the host's key. Only the authentication keys are written to the CryptoMemory. The host key, which is required to create the authentication keys, is not stored in the CryptoMemory; it resides only in the host. Thus, in the unlikely event that a CryptoMemory were "cracked," it does not contain enough information to create the right keys.

CryptoMemory devices are available in densities from 1 Kbit to 256 Kbits of user memory to accommodate a wide range of information storage and cost requirements. They have standard memory interfaces to microcontrollers and off-the-shelf readers that include a two-wire interface, ISO 7816-3 interface in T=0 Mode for wired asynchronous communications. Package options include 8-lead SOIC or PDIP plastic packages and modules for smartcard applications.

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Embedded Technology Magazine

This article first appeared in the January, 2008 issue of Embedded Technology Magazine.

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