Zymbit ZYMKEY 5: A 640-Key Security Module for Raspberry Pi

Zymbit ZYMKEY 5 is the kind of small upgrade that makes a Raspberry Pi far more trustworthy in the field. Reported by LinuxGizmos on October 10, the new hardware security module is a mini-HAT just 39 x 14 x 5.3 mm that plugs onto the first ten GPIO pins and gives a Pi 640 slots for cryptographic keys, up from just a handful on the ZYMKEY 4. For anyone deploying Pi-based gateways, kiosks or edge devices, it is a big jump in protection.

• Compatibility: Raspberry Pi Zero, Pi 4, Pi 5, Compute Module 4 and Compute Module 5, per LinuxGizmos.
• Key storage: 512 key pairs plus 128 external public keys, for 640 slots in total, versus three of each on the ZYMKEY 4.
• Physical security: two independent tamper-detection circuits that can trigger a notification or destroy keys when a perimeter is breached.
• Pricing: $79 developer kit with pre-release hardware, or $980 for a 20-pack ($49 each) and $8,400 for a 200-pack ($42 each).

What Does a Raspberry Pi Security Module Do?

A Raspberry Pi normally stores its secrets on the microSD card or SSD, where anyone with physical access can copy them. A hardware security module keeps private keys inside dedicated tamper-resistant hardware instead. The keys are generated and used on the module, so they never need to sit in readable form on the Pi's storage.

ZYMKEY 5 supports secp256k1, Ed25519, X25519, ECDH, ECDSA and AES-256, plus a hardware true random number generator. LinuxGizmos notes it also supports TLS client authentication for services such as AWS IoT, and Zymbit's store page describes it as AWS Qualified.

How Does ZYMKEY 5 Encrypt the Root Filesystem?

This is the headline feature for many deployments. ZYMKEY 5 works with Linux dm-crypt and LUKS to encrypt the Pi's root filesystem, with the unlock key held by the module. If someone pulls the storage out of a deployed device, the data is unreadable without that specific ZYMKEY attached. Communication between the Pi and the module is itself encrypted over I2C using ephemeral elliptic-curve keys.

Developers get Python, C and C++ APIs plus OpenSSL integration, so adding hardware-backed signing to an existing application does not mean rewriting it.

How Does Tamper Detection Work?

Two perimeter-detection circuits can monitor external tamper switches or a conductive enclosure. A new 12-pin JST connector replaces the previous micro-USB perimeter connector. When an external battery is connected, the battery-backed real-time clock, rated at 5 ppm, and the perimeter detection keep running even while the Pi is powered off. That means a device sitting in a remote cabinet can still notice an intrusion attempt overnight.

Which Raspberry Pi Projects Benefit Most?

ZYMKEY 5 makes the most sense for Pi deployments outside a locked home office: industrial gateways, point-of-sale terminals, remote sensors and Compute Module 5 products. If you are still choosing a board for a project like this, our Raspberry Pi buyer's guide compares every current model, and production builders may also like the Raspberry Pi CM5 programming jig for flashing modules in bulk.

When Can You Buy ZYMKEY 5?

The $79 developer kit includes pre-release hardware, an I/O and perimeter breakout board with cable, and a battery. Zymbit's store currently lists the dev kit as sold out, with 20-pack and 200-pack production configurations also listed. Expect more stock as production ramps. More single-board computer news lives in our mini computers section.

Sources: LinuxGizmos — October 10, 2026; Zymbit store: ZYMKEY 5 Dev Kit — accessed October 16, 2026.