# X-Ray Fault Injection in non-volatile memories of Power Off Devices

Paul Grandamme, Lilian Bossuet, Jean-Max Dutertre

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Paul Grandamme, Lilian Bossuet, Jean-Max Dutertre. X-Ray Fault Injection in non-volatile memories of Power Off Devices. JAIF 2024 - Journée thématique sur les attaques par injection de fautes, Sep 2023, Gardanne, France. hal-04935001

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# X-Ray Fault Injection in non-volatile memories of Power Off Devices

Paul Grandamme¹,²

PhD thesis supervised by Lilian Bossuet¹ and Jean-Max Dutertre²

¹Université Jean Monnet Saint-Etienne, CNRS, Institut d'Optique Graduate School, Laboratoire Hubert Curien UMR 5516, F-42023, SAINT-ETIENNE, France

²Mines Saint-Etienne, CEA Leti, Centre CMP, 13541 Gardanne, France

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MINES
Saint-Etienne

Une école de FIMT

September 28th 2023
## Fault Attack

Disturbing the device to modify its behavior to obtain information or disable internal protection mechanisms

<figure><img src="image_5.png" /><figcaption>Clock glitch</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Laser injection</figcaption></figure>

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /><figcaption>Electromagnetic
injection</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>Temperature variation</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>X-Ray irradiation
(MITIX Project [1, 3])</figcaption></figure>

<footnote>[1] Anceau S. et al. Nanofocused X-Ray Beam to Reprogram Secure Circuits. CHES 2017.</footnote>

<footnote>[3] Maingault L. et al. Laboratory X-rays Operando Single Bit Attacks on Flash Memory Cells. CARDIS 2021.</footnote>
Laser injection

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

Electromagnetic
injection

<figure><img src="image_13.png" /></figure>

## Benefits

High time and spatial accuracy

## Limitations

The device must be powered → some countermeasures exist

## Advantages

X-Ray can have an effect in non-volatile memories of power off devices
Table of contents

1. Flash memory, floating gate transistor and X-ray effects

* Flash Memory and floating gate transistor

* X-Ray effects on floating gate transistor

2. Experiments

3. Results

4. Conclusion
# Overview

1. Flash memory, floating gate transistor and X-ray effects

* Flash Memory and floating gate transistor

* X-Ray effects on floating gate transistor

2. Experiments

3. Results

4. Conclusion
<figure><img src="image_14.png" /></figure>

<figure><img src="image_15.png" /><figcaption>Floating gate transistors</figcaption></figure>

[4] S. Skorobogatov, 'Optical Fault Masking Attacks', in 2010 Workshop on Fault Diagnosis and Tolerance in Cryptography, Santa Barbara, CA, TBD: IEEE, Aug. 2010, pp. 23–29
NOT CHARGED

<figure><img src="image_16.png" /></figure>

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<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
NOT CHARGED

<figure><img src="image_18.png" /></figure>

CHARGED

<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /></figure>

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
# Overview

1. Flash memory, floating gate transistor and X-ray effects

* Flash Memory and floating gate transistor

* X-Ray effects on floating gate transistor

2. Experiments

3. Results

4. Conclusion
# TID mechanisms in floating gate transistor

<figure><img src="image_21.png" /></figure>

## Effect 1

* $e^/-/h^+$ pair created by radiation is separated by the electric field

* one of them escapes through the control gate

* the other one is injected into the floating gate

⇒ recombination with stored charges

⇒ decrease of the charge

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
<figure><img src="image_22.png" /></figure>

## Effect 2

* the charge can be trapped in the oxide

* Phenomenon is not significant because of the thinness of the oxides

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
<figure><img src="image_23.png" /></figure>

## Effect 3: *photoemission*

* charges stored in the floating gate get enough energy from the radiation to escape from the potential well

⇒ decrease of the stored charge

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
3 different effects:

* electron-hole pair generation in the oxide

* charge trapping in the oxide

* **photoemission**

[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013
<figure><img src="image_24.png" /></figure>

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
Influence of ionizing radiation on the threshold voltage
distribution

<figure><img src="image_25.png" /></figure>

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
<figure><img src="image_26.png" /></figure>

<footnote>[2] S. Gerardin et al., 'Radiation Effects in Flash Memories', IEEE Trans. Nucl. Sci., vol. 60, no. 3, pp. 1953-1969, Jun. 2013</footnote>
# Table of contents

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

* X-Ray setup

* Targets

* Protocol

3. Results

4. Conclusion
# Overview

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments
* X-Ray setup
* Targets
* Protocol

3. Results

4. Conclusion
<figure><img src="image_27.png" /></figure>

## Settings

* Tungsten (W) anode

* Source : 100kV and 45mA ⇒ photons with 40keV energy
Overview

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

* X-Ray setup

* Targets

* Protocol

3. Results

4. Conclusion
<figure><img src="image_28.png" /></figure>

## Targets settings

* 32-bit microcontroller with ARM Cortex-M3 core

* 128 kB of Flash memory (erase state: 0xFFFFFFFF)

* 2048 bitlines and 512 wordlines

* security bits preventing from reading memory if activated
1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

* X-Ray setup

* Targets

* Protocol

3. Results

4. Conclusion
<figure><img src="image_29.png" /></figure>
# Table of contents

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

3. Results

* X-Ray effects

* Time and thermal recuperation

4. Conclusion
Overview

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

3. Results

* X-Ray effects

* Time and thermal recuperation

4. Conclusion
<table><thead><tr><td>Color</td><td>Bit Value</td><td>Faulty</td><td>FGMOS state</td></tr></thead><tbody><tr><td>White</td><td>1</td><td>Yes</td><td>Discharged</td></tr><tr><td>Black</td><td>0</td><td>No</td><td>Charged</td></tr></tbody></table>

Before irradiation:

<figure><img src="image_30.png" /></figure>

After irradiation:

<figure><img src="image_31.png" /></figure>
<figure><img src="image_32.png" /></figure>
<figure><img src="image_33.png" /></figure>
1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

3. Results
* X-Ray effects
* Time and thermal recuperation

4. Conclusion
Time and thermal recovery

After irradiation:

<figure><img src="image_34.png" /></figure>

After time
recovery:

7 days @ room temperature

<figure><img src="image_35.png" /></figure>

After thermal
recovery:

2h @ 150°C

<figure><img src="image_36.png" /></figure>
Permanent VS non-permanent faults

<figure><img src="image_37.png" /></figure>
# Table of contents

1. Flash memory, floating gate transistor and X-ray effects

2. Experiments

3. Results

4. Conclusion
## Conclusion

* X-Ray can have an effect on non-volatile memories of power off devices

* Exponential dependance between the total ionizing dose and the number of faults

* Thermal recuperation is possible for the non-permanent faults

* Permanent faults are due to the discharge of the floating gate transistors

## Ongoing work

* Lead shield design and fabrication to target specific part of the device

* Application on cryptographic algorithm attack
Thank you for listening. Do you have any questions?

This work is funded by a french ANR program, along with the project POP.

Thanks to the MOPERE team (LabHC) for the access to the X-Ray source.

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LABORATOIRE
HUBERT CURIEN

MINES
 Saint-Etienne

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MINES
 Saint-Étienne

Une école de l'IMT

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CNSC - GRENoble IP - USA

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LCIS

Laboratoire de Conception
et d'Intégration des Systèmes

anr®
* 6T SRAM cell:

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* $NI2 \rightarrow$ Stuck at 0

* $NI1 \rightarrow$ Stuck at 1

* Thermal annealing possible

* Non-volatile memories:

* whole column is reset (Thermal annealing possible)

* single bit is reset

⇒ Same phenomenon
Maingault L. et al. Laboratory X-rays Operando Single Bit Attacks on Flash Memory Cells. CARDIS 2021.

* Use of a conventional W target X-rays source

* Perform frontside attack

* Some proposal of mask conception
<figure><img src="image_44.png" /></figure>

Stéphanie Anceau, Pierre Bleuet, Jessy Clédière, Laurent Maingault, Jean-Luc Rainard, and Rémi Tucoulou.

**Nanofocused x-ray beam to reprogram secure circuits.**

In Wieland Fischer and Naofumi Homma, editors, *Cryptographic Hardware and Embedded Systems - CHES 2017 - 19th International Conference, Taipei, Taiwan, September 25-28, 2017, Proceedings*, volume 10529 of *Lecture Notes in Computer Science*, pages 175–188. Springer, 2017.

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S. Gerardin, M. Bagatin, A. Paccagnella, K. Grürmann, F. Gliem, T. R. Oldham, F. Irom, and D. N. Nguyen.

**Radiation effects in flash memories.**

*IEEE Transactions on Nuclear Science*, 60(3):1953–1969, 2013.

<figure><img src="image_46.png" /></figure>

Laurent Maingault, Stéphanie Anceau, Manuel Sulmont, Luc Salvo, Jessy Clédière, Pierre Lhuissier, Emrick Beliard, and Jean-Luc Rainard.

**Laboratory x-rays operando single bit attacks on flash memory cells.**

In Vincent Grosso and Thomas Pöppelmann, editors, *Smart Card Research and Advanced Applications - 20th International Conference, CARDIS 2021, Lübeck, Germany, November 11-12, 2021, Revised Selected Papers*, volume 13173 of *Lecture Notes in Computer Science*, pages 139–150. Springer, 2021.

<figure><img src="image_47.png" /></figure>

Sergei Skorobogatov.

**Optical fault masking attacks.**

In Luca Breveglieri, Marc Joye, Israel Koren, David Naccache, and Ingrid Verbauwhede, editors, *2010 Workshop on Fault Diagnosis and Tolerance in Cryptography, FDTC 2010, Santa Barbara, California, USA, 21 August 2010*, pages 23–29. IEEE Computer Society, 2010.