Secure Serial EEPROM with 1-Wire Interface: Microchip AT21CS01-STUM10-T

The Microchip AT21CS01-STUM10-T represents a significant advancement in secure data storage for constrained and connected devices. This device is a 1-Kbit serial Electrically Erasable Programmable Read-Only Memory (EEPROM) that integrates a robust 1-Wire® interface with advanced hardware-based security features, making it an ideal solution for applications requiring authentication, secure storage, and intellectual property protection.

At its core, the AT21CS01 functions as a standard EEPROM, providing non-volatile storage for critical data such as calibration constants, configuration parameters, or small amounts of log data. Its 1-Wire interface drastically simplifies system design by reducing the number of connections to a single data line plus a ground return. This minimalist approach is invaluable for space-constrained applications like smart consumables, printed circuit board authentication, and medical disposables, where minimizing pins and connectors is paramount.

The true differentiator of this device is its embedded cryptographic engine. It features a hardware-based, FIPS 180-based Secure Hash Algorithm (SHA-256) engine and a guaranteed unique, factory-programmed 64-bit ROM identification number. This combination enables powerful challenge-response authentication protocols. A host system can verify the authenticity of a peripheral or consumable by issuing a challenge. The EEPROM uses its internal secret to compute a unique SHA-256 MAC (Message Authentication Code), which the host can then verify. This process effectively clones the device's secret, which is stored in a write-only, non-readable memory location, ensuring the key can never be exposed.

Furthermore, the memory array is partitioned into two main sections: a user EEPROM array and a dedicated Security Register. The Security Register contains the all-important secret and configuration bits that control device functionality, such as write protection for specific memory areas. This prevents unauthorized modification of firmware or critical data.

The device is offered in a compact 2-lead SOT-23 package, making it extremely easy to integrate into even the smallest of form factors. Its low power consumption is suitable for battery-powered and portable applications.

ICGOODFIND: The Microchip AT21CS01-STUM10-T is a highly integrated solution that marries the simplicity of the 1-Wire interface with formidable SHA-256 security. It provides a cost-effective and reliable method for adding strong authentication and secure data storage to products, safeguarding against counterfeiting and unauthorized access.

Keywords: Secure Authentication, 1-Wire Interface, SHA-256 Engine, Hardware Security, EEPROM Memory.