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--- backside:start [2018/02/20 21:25] – mcmaster
+++ backside:start [2018/02/20 21:54] – mcmaster
@@ Line 9: / Line 9: @@
 ====== Camera ======
+mcmaster: I bought an MU800 with the intention of removing the IR filter. I also might put silicon wafer in the imaging path to filter out the visible light. Unclear if my microscope optics can pass the IR light, say, even the relay lens. But I suppose if they have an IR filter it must pass some?
+Ordering some IR lasers
 ===== Sample commercial unit =====
@@ Line 24: / Line 28: @@
 ====== Optical fault injection ======
+Basic idea: change how the circuit switches current in order to introduce a glitch. For a combinitorial circuit you probably want a CW laser to keep the glitch active. If its a CPU, you probably want a pulsed laser to trigger the glitch for a short period of time
+{{:backside:transmission-spectrum-of-crystalline-silicon-from-the-visible-to-the-near-ir.png?400|}}
+Above: "FIGURE 3.1 Transmission spectrum of crystalline silicon from the visible to the near-IR." ([[https://www.researchgate.net/figure/Transmission-spectrum-of-crystalline-silicon-from-the-visible-to-the-near-IR_fig1_235941520|source]])
 In its simplest form, a CSP can be strobed with a camera flash
@@ Line 30: / Line 40: @@
 [[https://www.cl.cam.ac.uk/~sps32/ches2010-bumping.pdf|Sergei paper]] references using 1065 nm laser. The paper shows using IR objectives. So maybe a broadband source would work okay too.
+{{:backside:transmission-spectrum-of-crystalline-silicon-from-the-visible-to-the-near-ir_mod.png?400|}}
+Above: silicon transmission marked with bandgap and for 980 nm laser (commonly available)
+Possible sources:
+  * Photo flash, such as with mask
+  * 980 nm laser will have high attenuation (roughly 2% transmittance), but should work if power is high enough
+    * Specifically? Maybe 100's of mW, maybe even 500. Needs testing
+  * 1065 nm (ie 1064 nm from Nd:YAG) and such is probably ideal
+    * Must Nd:YAG are flashlamp pumped
+    * Depending on glitch target might want either flashlamp or diode pumped
 [[https://www.riscure.com/uploads/2017/09/Practical-optical-fault-injection-on-secure-microcontrollers.pdf|Riscure paper]]
-Solutions include:
+Commercial solutions include:
   * [[http://www.alphanov.com/40-optoelectronics-systems-and-microscopy-single-spot-laser-station.html|Alphanov]]
   * [[https://www.riscure.com/security-tools/inspector-fi/|Riscure Inspector FI]]
-  * ChipWispherer has voltage glitching. Could probably rig something similar up for optical glitching
+  * ChipWhispherer has voltage glitching. Could probably rig something similar up for optical glitching