Secure element explained: what the wallet chip protects

What a secure element is, which physical attacks it resists, what the ratings EAL5+ and EAL6+ mean, and how Ledger's single chip and BitBox's two chips differ.

Key points

A secure element is a chip built to resist attacks by someone who has the device in their hands, for example by measuring its power use or by firing a laser at it.
At Ledger, the secure element makes and stores the keys and drives the screen. At BitBox, the keys are made on an open microcontroller, and a secure chip limits password guessing without ever receiving them.
Ratings such as EAL6+ apply to the chip, not to the whole wallet.

What a secure element is

Most of the time, the danger to a hardware wallet comes from malware or tricks. A secure element is about a different danger: someone who has stolen the device and tries to pull the secret out of the chip itself. Ledger lists the defenses its chips have:

Attack	What it means	The defense Ledger names
Side channel	measuring the chip’s power use or electromagnetic radiation to learn the secret	countermeasures that hide both
Fault injection	disturbing the chip with a laser, heat, or voltage spikes to make it slip	light sensors, temperature sensors, and voltage glitch detectors
Reprogramming	loading other code onto the chip	the chip resists reprogramming

What the ratings mean

Secure elements are rated under the Common Criteria standard, abbreviated CC EAL. The higher the level, the more thoroughly the chip was tested against attacks; the scale goes up to EAL7+. Ledger says the Nano X uses a chip rated EAL5+, and the Nano S Plus and the Stax use chips rated EAL6+. BitBox says the BitBox02 Nova uses a secure chip rated EAL6+, and points out that “the certification applies to the chip, not to the complete wallet.”

Two designs

Ledger, one chip: the secure element makes and stores your private keys and drives the device’s screen. Its low-level code is not public, because the chip maker’s contract forbids it.

BitBox, two chips: an open-source microcontroller runs the wallet firmware, makes the keys, and signs transfers. It stores the wallet seed encrypted. A separate secure chip slows and limits password guessing, without ever receiving the seed or the private keys. To unlock the device, you need your password and secrets from both chips.

Each design has its argument: Ledger keeps the keys inside the hardened chip, BitBox keeps them in code anyone can check and uses the secure chip only as a guard.

What a secure element does not protect against

The chip protects the keys from someone who has the device. It does not stop you from confirming a transfer you were tricked into, and it does not protect the recovery phrase you wrote down. The guide Clear signing and blind signing shows the most common trick.

What you can do

Set a strong PIN or password on the device. The chip limits guessing, but a PIN like 1234 is the first one anyone tries.
Do not count on the chip if your recovery phrase is found. The words alone are enough to take your coins.
Compare the designs on the page of hardware wallets and choose the one whose trade-off you accept.

Next step

The guide Open source or closed explains why Ledger’s chip code is not public and how BitBox makes its code checkable.

The figures in this guide come from the archive and change with every data update. As of November 13, 2026.

Secure element explained: what the chip in a hardware wallet protects