The DS2460 SHA-1 Coprocessor with EEPROM is a hardware implementation of the ISO/IEC 10118-3 Secure Hash Algorithm (SHA-1), eliminating the need to develop software to perform the complex SHA computation required for authenticating SHA devices and for performing the validation of digitally signed service data. The DS2460 communicates with a microcontroller through the popular IC interface. Applications include hosts of access control and electronic payment systems for token authentication and service data validation as well as generation of one-time-use encryption keys for short message encryption and decryption for messages not exceeding the length of a SHA-1 result, which is 20 bytes.