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Hack proofing your network second edition - Part 9

Có rất nhiều loại khác nhau của epoxies và nhựa có thể được sử dụng để cung cấp bảo vệ thành phần. Một số vật liệu này có thể bị giải thể hoặc gỡ bỏ bằng cách sử dụng các hóa chất (chẳng hạn như Methylene Chloride hoặc axit nitric bốc khói). | 630 Chapter 14 Hardware Hacking Diffie-Hellman RSA DSS and Other Systems www.cryptography.com timingattack timing.pdf by Paul Kocher. Advanced Techniques Epoxy Removal and IC Delidding Encapsulation of critical components using epoxy or other adhesives is commonly done to prevent tampering and device access the microprocessor shown in Figure 14.9 is covered by a hard epoxy encapsulate to prevent probing .There are many different types of epoxies and resins that can be used to provide component protection. Some of this material can be dissolved or removed using chemicals such as Methylene Chloride or Fuming Nitric Acid . A quick-turn solution is to use a Dremel tool or drill with a wooden bit such as the shaft of a cotton swab or a toothpick . Moving the drill lightly along the epoxy surface will weaken and thin the bonding material. It is recommended that you take proper precautions and wear protective gear for this stage of the attack. Once the epoxy is removed from the component you may be able to begin probing the device. Figure 14.9 Circuit Board from Rainbow Technologies iKey 1000 For more complicated product designs IC delidding and analysis of the silicon die might need to take place especially if security features are in place to prevent proper reading from a memory device as described in the Memory Retrieval section .The goal of delidding is to get access to the actual die of the integrated circuit which could be a microprocessor analog or digital memory or programmable logic . IC delidding is extremely difficult without the use of proper tools because hazardous chemicals are often required and the underlying die is very fragile. Decapsulation products are offered by companies such as B G International www.bgintl.com that will aid in certain types of epoxy removal. www.syngress.com Hardware Hacking Chapter 14 631 Silicon Die Analysis Once the die is accessible a high-powered microscope can be used to analyze the actual die image.This can be done to .