Differences

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--- semi-invasive [2018/02/20 22:39] – mcmaster
+++ semi-invasive [2019/12/07 22:14] – W mcmaster
@@ Line 1: / Line 1: @@
+====== UV EPROM erase ======
+EPROM/EEPROM/flash can be erased by shining UV light or x-rays into the surrounding oxide. This slightly oxidizes it, letting the floating gate to drain out.
-====== Non-invasive attacks ======
+===== Nail polish =====
-[[jtag|JTAG]]
+Usually a masking compound is applied to selectively block UV to the firmware, with red nail polish being the most popular or at least traditional.
-[[ripping|Ripping firmware]]
+McMaster
+  - [[Revlon ColorStay Gel Envy Longwear Nail Enamel, Queen of Hearts|https://www.amazon.com/gp/product/B00LT8S30G/]]
+  - Bought at local store a while back and it seems to work well enough
+  - Bulk removal with acetone, but leaves some residue around edges
+  - Remaining residue softened with aceotne
+  - Remove using single hair brush if possible
+  - Can be more aggressive with PP monofilament wire
+  - Cold H2SO4 also works well. Wash with IPA then acetone
+    - Washing with water may really heat up the mixture
-[[dpa|Differential power analysis]]
+===== Angle =====
+Some chips with shielding against this type of attack can be bypassed by shining light at a sharp angle
+===== Mask =====
+Use nail polish or similar compound. Most materials will block UV, so just about anything will work. Nail polish tends to be easy to work with including application and (acetone) removal.
+Use a fine point pipette for simple chips.
+For finer masks, place the chip in a large bowl with a shallow layer of acetone at the bottom. This creates an acetone "shield gas" to prevent tools from drying out. Then put some nail polish on a single bristle (maybe held by tweezers) and it should not dry out, allowing you to paint it onto the die.
+====== X-ray EPROM erase ======
+TODO: add links to misc papers