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2020-03-02
Serpanos, Dimitrios, Stachoulis, Dimitrios.  2019.  Secure Memory for Embedded Tamper-Proof Systems. 2019 14th International Conference on Design Technology of Integrated Systems In Nanoscale Era (DTIS). :1–4.

Data leakage and disclosure to attackers is a significant problem in embedded systems, considering the ability of attackers to get physical access to the systems. We present methods to protect memory data leakage in tamper-proof embedded systems. We present methods that exploit memory supply voltage manipulation to change the memory contents, leading to an operational and reusable memory or to destroy memory cell circuitry. For the case of memory data change, we present scenaria for data change to a known state and to a random state. The data change scenaria are effective against attackers who cannot detect the existence of the protection circuitry; furthermore, original data can be calculated in the case of data change to a known state, if the attacker identifies the protection circuitry and its operation. The methods that change memory contents to a random state or destroy memory cell circuitry lead to irreversible loss of the original data. However, since the known state can be used to calculate the original data.

2017-05-16
Torii, Naoya, Yamamoto, Dai, Matsumoto, Tsutomu.  2016.  Evaluation of Latch-based Physical Random Number Generator Implementation on 40 Nm ASICs. Proceedings of the 6th International Workshop on Trustworthy Embedded Devices. :23–30.

In the age of the IoT (Internet of Things), a random number generator plays an important role of generating encryption keys and authenticating a piece of an embedded equipment. The random numbers are required to be uniformly distributed statistically and unpredictable. To satisfy the requirements, a physical true random number generator (TR-NG) is used. In this paper, we implement a TRNG using an SR latch on 40 nm CMOS ASIC. This TRNG generates the random number by exclusive ORing (XORing) the outputs of 256 SR latches. We evaluate the random number generated using statistical tests in accordance with BSI AIS 20/31 and using an IID (Independent and Identically Distributed) test, and the entropy estimation in accordance with NIST SP800-90B changing the supply voltage and environmental temperature within its rated values. As a result, the TRNG passed all the tests except in a few cases. From this experiment, we found that the TRNG has a robustness against environmental change. The power consumption is 18.8 micro Watt at 2.5 MHz. This TRNG is suitable for embedded systems to improve security in IoT systems.