The App Note starts by noting that for over a decade, SHA-1 authentication was used to effectively protect intellectual property (IP) from counterfeiting and illegal copying. But as computer technology information processing has advanced, users want an even higher level of security.
Now, a secure authenticator and a companion secure coprocessor implement SHA-256 authentication. This new technology provides advanced physical security to deliver low-cost IP protection, clone prevention, and peripheral authentication. This note explains the general logistics of a SHA-256-based security system and discusses the bidirectional authentication functionality that the authentication system utilises. Implementing a secure authentication system requires linking a host system with a sensor/peripheral module. The system presented in the paper consists of a SHA-256 secure authenticator plus a SHA-256 secure coprocessor. The host communicates with the authenticator and the coprocessor over the industry-standard I2C bus. Additional features of Maxim's part include a 3 kb user EEPROM array, multiple memory protection methods and advanced physical security, combine to provide IP protection, clone prevention, and authentication.
Read the complete note at; www.maximintegrated.com/en/app-notes/index.mvp/id/5785