Follow+Star PublicNumber, don’t miss the wonderful content

Source | IoVSecurity

Arrangement | strongerHuang

Since the birth of MCU in the 1970s, the technology for cracking chips and the solutions to prevent chips from being cracked have been in a constant chase of “the higher the skill, the higher the devil”, with one mountain higher than another.

This article will share the development history of microcontrollers in terms of security protection, and at the end of the article, summarize the advantages and disadvantages of the currently highest security level smart card chips.

In the early 1970s, embedded systems were composed of separate components such as:CPU, ROM, RAM, I/O cache, serial ports, and other communication and control interfaces.

During this period, there were almost no protective measures to prevent intruders from copying the data in the ROM area on the single board machine, except for legal protections.

With the development of large-scale integrated circuit technology, the central processing unit (CPU), data memory (RAM), program memory (ROM), and other I/O communication ports have been integrated into a single microcontroller chip, replacing the single board machine. As shown:

With the increase in intruders, the MCU later added security fuses to prohibit access to data for its own safety. As shown:

Later, MCU manufacturers made security fuses part of the memory array, as shown:

By locking specific address areas of information upon power-up, it can be used as a security fuse.Or use a password to control access to memory.For example, Texas Instruments’ MSP430F112 can only perform read-back operations after entering the correct 32-byte password.If not entered, only after erasing the byte password can read-back operations be performed.Although this protection method seems more effective than previous ones, it has some disadvantages that can be cracked using low-cost non-invasive attacks, such as timing analysis and power consumption. If the state of the security fuse is part of the memory after power-up or reset, it gives attackers the opportunity to crack it using power noise, forcing the route into an erroneous state in the memory.

Using top metal network design increases the difficulty of intrusion.All grids are used to monitor short circuits and open circuits, and once triggered, will cause the memory to reset or clear. As shown:

In recent years, some smart cards use memory bus encryption (Bus Encryption) technology to prevent probing attacks. As shown:

For developers, choosing a more secure design microcontroller can provide better protection.Compared to most microcontrollers, even smart cards designed ten years ago can offer better protection.Modern smart cards provide more anti-attack protection, with internal voltage sensors protecting against power glitch attacks, over-voltage and under-voltage protection.Clock frequency sensors prevent attacks that lower clock frequencies due to static analysis.They can also prevent clock noise attacks that increase clock frequencies.Top metal grids and internal bus hardware encryption can prevent micro-probing attacks.However, compared to microcontrollers, smart card chips also have disadvantages, such as:The chip is expensive, and small batches are difficult to obtain.Development tools are expensive, and confidentiality agreements must be signed with manufacturers, even for manuals.Many manufacturers only sell large quantities of smart cards to specific customers.Another disadvantage is that the I/O functionality is limited; ordinary smart card chips usually only have ISO7816 interfaces, and very few have separate I/O ports.This means that in most applications, they cannot replace microcontrollers and can only be used in industries with very high security requirements, such as:Pay TV set-top boxes, bank cards, SIM cards, second-generation ID cards, high-end encryption chips, and so on.The application of smart card chips in the field of encryption chips will be a good direction.Because smart card chips have high security levels and limited IO resources.While ordinary MCUs have abundant hardware resources, their security level is low, and some key algorithms and operating parameters can be stored in special forms in smart card chips to achieve powerful functions with high security strength.

The endless struggle between groups attempting to break protective mechanisms and manufacturers continuously introducing new security measures has no end.“The higher the skill, the higher the devil,” or “the evil cannot suppress the righteous,” will continue to unfold between the two factions!

Disclaimer:This article’s material is sourced from the internet, and copyright belongs to the original author. If there are copyright issues, please contact me for deletion.

Reply to “MCU” “Microcontroller” “Science Knowledge” in the background to read more related articles.

Click “Read Original” to see more shares, welcome to share, collect, like, and review.