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The Secure Element Chip: How It Keeps Your Ledger Secure

Read 4 min
Medium
Ledger devices on a podium
KEY TAKEAWAYS:
— Hardware wallets require chips to operate: for storing private keys and signing transactions.

— Different hardware wallets will use different chips and may not implement them in the same manner.

— Ledger hardware wallets use a specialized chip called the Secure Element. These chips are tamper-proof and offer the highest level of protection for your digital assets.

When choosing a hardware wallet, its inner components are often overlooked. But the chip your hardware wallet uses and how it’s implemented impacts the security of your device. To explain, hardware wallets don’t store crypto, they store your private keys; the keys that grant access to your digital assets. If anyone gains access to your private keys, it’s game over.

So a hardware wallet’s main purpose is to keep your private keys safe from attackers attempting to extract them. But to store those private keys and sign transactions, your device requires a chip. And that chip needs to offer protection from both online and physical attacks as well as performance. 

At Ledger, we only use one of the most advanced chips on the market: the Secure Element. This chip generates and stores your private keys, and is responsible for driving your Ledger device’s secure screen. The Secure Element also runs Ledger’s custom operating system BOLOS which keeps your apps isolated from one another. 

In short, the Secure Element is one of the key reasons your Ledger hardware wallet is so secure. But why is it so important, and why is it so effective compared to other hardware wallet chips? 

To understand fully, let’s dive into why hardware wallets need chips in the first place.

Understanding the Security of Hardware Wallet Chips

All hardware wallets rely on chips to store private keys, operate apps, and drive their screens. 

Some hardware wallets will use a single chip, whereas others might use a combination of chips.

However, it’s important to note that not all chip types provide the same level of resistance against attacks. You wouldn’t want to protect your digital assets with a chip used in a vacuum cleaner or microwave, right? Even the chips used for smartphones and laptops aren’t designed to protect private keys. Simply, most chips are built for performance, not security. 

With that in mind, let’s look at the types of chips that hardware wallets typically use and see how they measure up.

Microcontroller Unit

microcontroller unit chip

A generic Microcontroller unit, or MCU in short, is found in devices such as microwaves and TV remotes. While these chips provide a lot of flexibility for their operations, they aren’t resistant to physical attacks. In particular, they tend to be vulnerable to inexpensive attacks such as voltage and clock glitching.

While introducing a passphrase feature on an MCU chip will help mitigate these risks, even that method introduces a single point of failure. If your passphrase is too simple, a hacker may be able to work it out. If your passphrase is too complicated, you risk forgetting it or recording it incorrectly.

Safe Memory Chip

safe memory chip

Another chip used in hardware wallets is the Safe Memory chip. These provide several countermeasures against physical attacks but they don’t have the certification you would get from an evaluation by a Security lab. Without this certification, you can’t be sure the chip is as secure as it claims. As a result, these chips aren’t suitable for bank cards or passports.

When it comes to hardware wallets, using a Safe Memory chip isn’t simple. To get a little technical, Safe Memory chips perform scalar multiplication on a single elliptic curve. This doesn’t work for signing Bitcoin transactions, so hardware wallets with Safe Memory chips will always need a second chip to handle the signing process.

This creates a vulnerability. Sending the private key out of its Safe Memory chip to the MCU opens up the perfect opportunity for side-channel attackers.

The Secure Element

The Secure Element is a highly specialized chip commonly used in passports and credit cards. You likely use these chips on multiple devices, in any environment where your most sensitive personal data needs to be secured and concealed.

Secure Element chips are the most secure option for a hardware wallet.  They stand out for their security features, but also their versatility. A secure Element can store private keys and handle the signing process, plus, they can protect against physical attacks and have the certification to prove it.

Why Are Secure Element Chips So Secure?

Secure Element chips are so secure mainly due to two important factors: their ability to withstand attacks and their certification.  

The Secure Element Protects Your Wallet From Attacks

If you’re not a developer (and most of us aren’t) you may be wondering exactly what kind of attacks the Secure Element protects you from. Some Secure Elements may protect you from even more attacks than just these, but let’s dive into some of the most common attacks.

Side channel attacks

A side-channel attack is when a hacker analyzes physical signals coming from a device’s operating system and embedded applications to get insights into how it behaves and which secret data it uses.

A Secure Element chip has complex countermeasures to hide its electromagnetic radiation and power usage, protecting it against those who want to listen in.

Fault Attacks 

Fault attacks involve an attacker aiming to perturb the physical execution of functions by your operating system and embedded applications. For example, the attacker might use a laser beam to bypass security mechanisms such as forcing the device to accept an incorrect PIN code.

The Secure Element has an efficient fault detection system, including light detectors for laser fault injection, temperature sensors, and voltage glitch detectors.

Software attacks

Software attacks involve a bad actor manipulating your device’s operating system or embedded apps, hoping to cause unexpected behaviors. 

The Secure Element prevents this attack as it is resistant to reprogramming. Once the chip is programmed, it can’t run any other software.

Secure Element Chips are Certified by Security Labs

Secondly, unlike Safe Memory chips, Secure Element chips are certified, having undergone testing by a third-party security lab. Certification is a crucial part of their security model. Typically,  Secure Elements are rated according to the CC EAL standard (also known as EAL).

CC stands for Common Criteria and represents an international standard for evaluating hardware and software products. Then the EAL stands for Evaluation Assurance Level. This rating measures how secure a Secure Element is; from its physical resistance to attacks to vulnerabilities in its entire supply chain.

The rating is simple: the higher the EAL level, the more secure the Secure Element chip is. There are 7 CC EAL levels, from low security to the highest security assurance.

How Does Ledger Approach the Secure Element in its Devices

Ledger devices use the Secure Element to generate and store private keys for your crypto assets. While other hardware wallets use the Secure Element, Ledger has a unique approach to its implementation.

Ledger’s Secure Element Runs a Custom Operating System: BOLOS

The Secure Element in Ledger devices runs a custom operating system named BOLOS. Combined with the genuine-check mechanism in Ledger Live, users can verify they are running the legitimate operating system and embedded applications.

Secure Element drives the Secure Screen

Ledger devices are also unique for using the Secure Element to drive their screens. With Ledger, what you see is what you sign. The Secure screen on your device will always show the accurate intended address of your transaction. That means even if your internet-connected device, such as your laptop or smartphone, is infected with malware, you can trust the transaction details on your Ledger device.

Ledger’s Secure Element Chips Have EAL 5+ and EAL6+ Certifications

Ledger devices have an EAL 5+ or an EAL 6+ certification depending on which device you get. The Ledger Nano X uses a Secure Element that is EAL5+ certified, whereas the Ledger Nano S Plus and Ledger Stax use a Secure Element that is EAL6+ certified.

Both EAL5 and EAL6 certifications guarantee the chip has undergone extensive testing by a third party to meet high-security standards. As mentioned, the scale only goes up to EAL7+, so the Secure Element chips in Ledger hardware wallets are extremely secure, with measures in place to protect you from physical and remote hacking attempts. 

The Secure Element: An Integral Component of Your Ledger Device

The chip your hardware wallet uses is incredibly important. When it comes down to making crypto transactions, you need three things to be fully secure. 

Firstly, you need a secure enclave: a chip resistant to physical hacking. This is handled by the Secure Element for Ledger devices. Next, you need to implement cryptography in that enclave, which is exactly what Ledger’s custom operating system BOLOS does for the Secure Element. Finally, you need a way to verify the authenticity of the transaction’s intent. With Ledger’s Secure screen driven directly by the Secure Element, Ledger devices tick off all three prerequisites. 

The inherent security features of a Secure Element, alongside Ledger’s proven security model, arm your Ledger device with the tools it needs to protect your digital assets. So what are you waiting for? Get yourself a Ledger hardware wallet and start transacting with confidence.


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