Inventors
Ari Juels
Publication date
2019/6/13
Patent office
US
Application number
15778140
Description
Systems and methods are described for providing a secure counter that is resistant to rollback attacks. In an exemplary embodiment, a tag memory, such as an RFID or NFC tag, is provided with a counter value, a verification value, and a digitally signed hash chain head value. The tag is initialized with a counter value of zero and a random initial verification value. The hash chain head value is initialized by applying a cryptographic hash function to the initial verification value a predetermined number of times. The counter is updated by incrementing the counter value and applying the hash function to the verification value. The counter is verified by determining the number of times the hash function must be applied to the verification value to reach the hash chain head value. Embodiments using a plurality of sub-counters are also described.
Total citations
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