Understand and Address Threats to Cryptographic Systems

Sep 10, 2020

Zia A. Sardar  By: Zia A. Sardar
 Principal Member of Technical Staff, Maxim Integrated 

All of our connected systems—from pulse oximeters connected to patients in a hospital to printer cartridges to IoT devices—face constant threats from hackers. In this post, we'll take a look at a few of these threats and learn how to protect your devices from them.

Developers today are facing threats to systems as well as to security ICs. Since system-related threats are well-documented, we'll focus here on threats to security ICs. A security IC can be attacked by one or more of the following methods:

  • Side-channel attacks, including glitch attacks (active) and differential power analysis (passive).
  • Invasive attacks, such as decapping and micro-probing to find open ports and traces that can be exploited.
  • Line snooping, such as a man-in-the-middle attack.
  • Memory array tampering, such as a cold boot attack.

Side-channel attacks are mostly noninvasive attacks; in other words, they do not destroy the IC. A side channel includes any information available as a side effect of the physical implementation of hardware, including power consumption and injection of faults. A glitch attack is an example. In Figure 1, you'll see a side-channel attack using clock glitches, which provides an example of a noninvasive attack. Someone with the right skills could examine the unknown output from a clock glitch or sped-up clock to discover a pattern that could ultimately reveal an encryption key.

Active side-channel attack is an example of a noninvasive attack.Figure 1. Active side-channel attack is an example of a noninvasive attack.

Decapping and micro-probing, which physically investigate various features of the IC, are invasive attacks that can destroy the IC. Also known as de-capping, decapsulation involves soaking the plastic package that encapsulates the silicon die in fuming nitric acid to melt the package away (Figure 2).

Semiconductor packages are vulnerable to invasive attacks. Figure 2. Semiconductor packages are vulnerable to invasive attacks.

Before the plastic package is soaked, the lead frame that holds the semiconductor die is typically secured on a frame. After the package has melted away, the die is exposed, presenting the hacker with an opportunity to directly probe all of the available pads—even the pads that the manufacturer has used for internal setup (Figure 3). To access the device's secrets, the hacker can also polish away the top protective glass to gain access to the device's internal interconnects.

Hackers can directly probe available pads on a chip (top view) Figure 3. Hackers can directly probe available pads on a chip (top view).

What can you do to prevent hackers from breaking into a secure device? One of the most effective things you can do is to design with a device developed with security features as well as built-in protection against attacks. For example, Maxim Integrated provides a portfolio of secure devices with robust countermeasures to protect against the kinds of attacks we've been discussing. Some of their key security features include:

  • Patented physically unclonable function (PUF) technology to secure device data.
  • Actively monitored die shield that detects and reacts to intrusion attempts.
  • Cryptographic protection of all stored data from discovery.
Learn more about how security devices protect against attacks by reading my tutorial, "Cryptography: Planning for Threats and Countermeasures."