215 research outputs found
Circuit Techniques for Low-Power and Secure Internet-of-Things Systems
The coming of Internet of Things (IoT) is expected to connect the physical world to the cyber world through ubiquitous sensors, actuators and computers. The nature of these applications demand long battery life and strong data security. To connect billions of things in the world, the hardware platform for IoT systems must be optimized towards low power consumption, high energy efficiency and low cost. With these constraints, the security of IoT systems become a even more difficult problem compared to that of computer systems. A new holistic system design considering both hardware and software implementations is demanded to face these new challenges.
In this work, highly robust and low-cost true random number generators (TRNGs) and physically unclonable functions (PUFs) are designed and implemented as security primitives for secret key management in IoT systems. They provide three critical functions for crypto systems including runtime secret key generation, secure key storage and lightweight device authentication. To achieve robustness and simplicity, the concept of frequency collapse in multi-mode oscillator is proposed, which can effectively amplify the desired random variable in CMOS devices (i.e. process variation or noise) and provide a runtime monitor of the output quality. A TRNG with self-tuning loop to achieve robust operation across -40 to 120 degree Celsius and 0.6 to 1V variations, a TRNG that can be fully synthesized with only standard cells and commercial placement and routing tools, and a PUF with runtime filtering to achieve robust authentication, are designed based upon this concept and verified in several CMOS technology nodes. In addition, a 2-transistor sub-threshold amplifier based "weak" PUF is also presented for chip identification and key storage. This PUF achieves state-of-the-art 1.65% native unstable bit, 1.5fJ per bit energy efficiency, and 3.16% flipping bits across -40 to 120 degree Celsius range at the same time, while occupying only 553 feature size square area in 180nm CMOS.
Secondly, the potential security threats of hardware Trojan is investigated and a new Trojan attack using analog behavior of digital processors is proposed as the first stealthy and controllable fabrication-time hardware attack. Hardware Trojan is an emerging concern about globalization of semiconductor supply chain, which can result in catastrophic attacks that are extremely difficult to find and protect against. Hardware Trojans proposed in previous works are based on either design-time code injection to hardware description language or fabrication-time modification of processing steps. There have been defenses developed for both types of attacks. A third type of attack that combines the benefits of logical stealthy and controllability in design-time attacks and physical "invisibility" is proposed in this work that crosses the analog and digital domains. The attack eludes activation by a diverse set of benchmarks and evades known defenses.
Lastly, in addition to security-related circuits, physical sensors are also studied as fundamental building blocks of IoT systems in this work. Temperature sensing is one of the most desired functions for a wide range of IoT applications. A sub-threshold oscillator based digital temperature sensor utilizing the exponential temperature dependence of sub-threshold current is proposed and implemented. In 180nm CMOS, it achieves 0.22/0.19K inaccuracy and 73mK noise-limited resolution with only 8865 square micrometer additional area and 75nW extra power consumption to an existing IoT system.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138779/1/kaiyuan_1.pd
Nonuniform-spaced Critical Behavior of Dynamical Quantum Phase Transitions in Multi-band Bloch Hamiltonian
We investigate the dynamical quantum phase transition (DQPT) in the
multi-band Bloch Hamiltonian of the one-dimensional periodic Kitaev model after
a quench from a Bloch band. Our study goes beyond the limitations of previous
works that primarily focused on two-band models and reveals significant
differences in DQPT between the two-band and multi-band systems. Our results
show that only the quench from the Bloch states, which causes the band gap to
collapse at the critical point, induces the DQPT after crossing the quantum
phase transition; otherwise, the DQPT will not occur. Additionally, the
critical times of the DQPT are not evenly spaced due to the deviation in the
critical momentum caused by the non-analytic singularities of the Pancharatnam
geometric phase. Our findings provide a better understanding of the
characteristics of non-equilibrium systems surrounding DQPTs.Comment: 9 pages, 10 figure
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A miRNA-HERC4 pathway promotes breast tumorigenesis by inactivating tumor suppressor LATS1.
The E3 ligase HERC4 is overexpressed in human breast cancer and its expression levels correlated with the prognosis of breast cancer patients. However, the roles of HERC4 in mammary tumorigenesis remain unclear. Here we demonstrate that the knockdown of HERC4 in human breast cancer cells dramatically suppressed their proliferation, survival, migration, and tumor growth in vivo, while the overexpression of HERC4 promoted their aggressive tumorigenic activities. HERC4 is a new E3 ligase for the tumor suppressor LATS1 and destabilizes LATS1 by promoting the ubiquitination of LATS1. miRNA-136-5p and miRNA-1285-5p, expression of which is decreased in human breast cancers and is inversely correlated with the prognosis of breast cancer patients, are directly involved in suppressing the expression of HERC4. In summary, we discover a miRNA-HERC4-LATS1 pathway that plays important roles in the pathogenesis of breast cancer and represents new therapeutic targets for human breast cancer
Dynamics of the Geometric Phase in Inhomogeneous Quantum Spin Chains
The dynamics of the geometric phase are studied in inhomogeneous quantum spin
chains after a quench. Analytic expressions of the Pancharatnam geometric phase
(PGP) are derived, for both the period-two quantum Ising chain
(QIC) and the disordered QIC. In the period-two QIC, due to the periodic
modulation, the PGP changes with time at the boundary of the Brillouin zone,
and consequently, the winding number
based on
the PGP is not quantized and thus not topological anymore. Nevertheless, the
PGP and its winding number show non-analytic singularities at the critical
times of the dynamical quantum phase transitions (DQPTs). This relation between
the PGP and the DQPT is further confirmed in the disordered QIC, where the
winding number is not defined. It is found that the critical time of DQPT
inherited from the homogeneous system and the additional one induced by the
weak disorder are also accompanied by the non-analytic singularity of the PGP,
by decomposing the PGP into each quasiparticle mode. The connection between the
non-analytic behavior of the PGP at the critical time and the DQPT, regardless
of whether the winding number is topological, can be explained by the fact that
they both arise when the Loschmidt amplitude vanishes.Comment: 14 pages, 8 figure
Dominant Eigenvalue-Eigenvector Pair Estimation via Graph Infection
We present a novel method to estimate the dominant eigenvalue and eigenvector
pair of any non-negative real matrix via graph infection. The key idea in our
technique lies in approximating the solution to the first-order matrix ordinary
differential equation (ODE) with the Euler method. Graphs, which can be
weighted, directed, and with loops, are first converted to its adjacency matrix
A. Then by a naive infection model for graphs, we establish the corresponding
first-order matrix ODE, through which A's dominant eigenvalue is revealed by
the fastest growing term. When there are multiple dominant eigenvalues of the
same magnitude, the classical power iteration method can fail. In contrast, our
method can converge to the dominant eigenvalue even when same-magnitude
counterparts exist, be it complex or opposite in sign. We conduct several
experiments comparing the convergence between our method and power iteration.
Our results show clear advantages over power iteration for tree graphs,
bipartite graphs, directed graphs with periods, and Markov chains with
spider-traps. To our knowledge, this is the first work that estimates dominant
eigenvalue and eigenvector pair from the perspective of a dynamical system and
matrix ODE. We believe our method can be adopted as an alternative to power
iteration, especially for graphs.Comment: 13 pages, 8 figures, 3 table
Dynamical relaxation behavior of extended XY chain with gapless phase following a quantum quench
We investigate the dynamical relaxation behavior of the two-point correlation
in extended XY models with a gapless phase after quenches from various initial
states. Specifically, we study the XY chain with gapless phase induced by the
additional interactions: Dzyaloshinskii-Moriya interaction and XZY-YZX type of
three-site interaction. When quenching from the gapped phase, we observe that
the additional interactions have no effect on the relaxation behavior. The
relaxation behavior is and for
the quench to the commensurate phase and the incommensurate phase,
respectively. However, when quenching from the gapless phase, we demonstrate
that the scaling behavior of is changed to for
the quench to the commensurate phase, and the decay of
follows or for the quench to the incommensurate
phase depending on the parameters of pre-quench Hamiltonian. We also establish
the dynamical phase diagrams based on the dynamical relaxation behavior of
in the extended XY models.Comment: 12 pages, 10 figure
ASCH-PUF: A "Zero" Bit Error Rate CMOS Physically Unclonable Function with Dual-Mode Low-Cost Stabilization
Physically unclonable functions (PUFs) are increasingly adopted for low-cost
and secure secret key and chip ID generations for embedded and IoT devices.
Achieving 100% reproducible keys across wide temperature and voltage variations
over the lifetime of a device is critical and conventionally requires large
masking or Error Correction Code (ECC) overhead to guarantee. This paper
presents an Automatic Self Checking and Healing (ASCH) stabilization technique
for a state-of-the-art PUF cell design based on sub-threshold inverter chains.
The ASCH system successfully removes all unstable PUF cells without the need
for expensive temperature sweeps during unstable bit detection. By accurately
finding all unstable bits without expensive temperature sweeps to find all
unstable bits, ASCH achieves ultra-low bit error rate (BER), thus significantly
reducing the costs of using ECC and enrollment. Our ASCH can operate in two
modes, a static mode (S-ASCH) with a conventional pre-enrolled unstable bit
mask and a dynamic mode (D-ASCH) that further eliminates the need for
non-volatile memories (NVMs) for storing masks. The proposed ASCH-PUF is
fabricated and evaluated in 65nm CMOS. The ASCH system achieves "0" Bit Error
Rate (BER, < 1.77E-9) across temperature variations of -20{\deg}C to
125{\deg}C, and voltage variations of 0.7V to 1.4V, by masking 31% and 35% of
all fabricated PUF bits in S-ASCH and D-ASCH mode respectively. The prototype
achieves a measured throughput of 11.4 Gbps with 0.057 fJ/b core energy
efficiency at 1.2V, 25{\deg}C.Comment: This paper has been accepted to IEEE Journal of Solid-State Circuits
(JSSC
High Glucose Predisposes Gene Expression and ERK Phosphorylation to Apoptosis and Impaired Glucose-Stimulated Insulin Secretion via the Cytoskeleton
10.1371/journal.pone.0044988PLoS ONE79
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