Download Entropy Extraction in Metastability-base TRNG

Entropy Extraction in
Metastability-based TRNG
Presented by
Cheng Chung Wang & Hsi Shou Wu
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Outline
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Background
Motivation
Implementation and analysis
Conclusion
Discussion
Background
• TRNG : True Random Number Generators
• Entropy : Natural Sources
– Cosmic rays
– Stray electromagnetics waves
– Thermal noise
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Background cont’d
• Process variation and operating condition
will impact the output of TRNG circuits
Temperature
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Fabrication defect
TRNG
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Operating voltage
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Background cont’d
• Bias Removal Techniques
– Post-processing techniques
– Calibration techniques
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Background cont’d
• Post-processing techniques
– XOR
– Von Neumann corrector (entropy extractor)
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Background cont’d
• Calibration
– Phase of clock signal
– Charge injection
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Motivation
• Several proposed biased removal circuit.
• Which one is the best solution?
• “Action speaks louder than words”
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Implementation and analysis
• TRNG without correction
Advanced technology
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Implementation and analysis
• With XOR
Depend on the max entropy one
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Implementation and analysis
• With Von Neumann corrector
Enhance entropy a lot
Drawback:
1. not generate at const rate!
2. Effective bit rate decrease with
technology scaling
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Implementation and analysis
• TRNG with calibration
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Implementation and analysis
• TRNG with calibration
Increase entropy but remain const
output rate
Less energy overhead
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Implementation and analysis
• TRNG with calibration
Tradeoff between number of bits
entropy and energy consumption
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Conclusion
• 1. Modern security systems need on-chip true
random number generators.
• 2. Conventional post-processing techniques are
not efficient for simple TRNG
– Physical calibration techniques are required .
– provide a greater flexibility for trading off entropy
for energy
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Discussion
1. Is the referenced model (dual inverter) representative?
2. Will the results change if we also run Monte Carlo
simulation in other parameters (temperature or
voltage drop)?
3. Would the area overhead be a huge issue?
4. As technology scaled down, dose the experiment
result still make sense?
5. Is bit generation rate a more important issue?
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