Data Remanence Effects on Memory Based Entropy Collection for RFID Systems

Random number generation is a fundamental security primitive. This relatively simple requirement is beyond the capacity of passive RFID (Radio Frequency IDentification) tags, however. A recent proposal, Fingerprint Extraction and Random Number Generation in SRAM (FERNS), uses onboard RAM as a randomness source. Unfortunately, practical considerations prevent this approach from reaching its full potential. First, the amount of RAM available for utilization as a randomness generator may be severely restricted due to competition with other system functionalities. Second, RAM is subject to data remanence; there is a period after losing power during which stored data re-mains intact in memory.