For years, the gold standard of hardware wallet caution was simple: never let the device talk to anything. Foundation Devices built its reputation on that idea, and now it is teaching its newest wallet to use Bluetooth.
Zach Herbert, co-founder and CEO of Foundation Devices, has been walking people through QuantumLink, the company’s secure Bluetooth protocol for the Passport Prime hardware wallet. The pitch is ambitious: live connectivity, the kind of isolation air-gapped setups were built to provide, and encryption designed with future quantum threats in mind.
What QuantumLink actually does
Foundation’s earlier air-gapped approach moved data around with QR codes. One screen displays a code, the other scans it, and the information crosses the gap without any cable or radio involved.
QuantumLink replaces that shuffle with a real-time Bluetooth connection to Envoy, Foundation’s companion app. According to Herbert’s explanation, the link handles onboarding, transaction signing, firmware updates and syncing.
Foundation’s answer is physical separation. Passport Prime uses a dedicated, isolated Bluetooth chip that runs independently from KeyOS, the wallet’s primary security processor.
That chip carries the traffic, but it is never allowed to read it. Every message moving through it is end-to-end encrypted before it arrives.
The cryptography under the hood
QuantumLink relies on two cryptographic tools working in sequence. CRYSTALS-Kyber handles key exchange, the step where the wallet and app agree on a shared secret.
ChaCha20-Poly1305 then takes over to encrypt the actual messages. Kyber sets up the lock, and ChaCha20-Poly1305 keeps every individual conversation behind it.
Kyber is the post-quantum component of the stack. Its job is to keep that initial handshake secure even against attackers equipped with quantum computers, not just against today’s conventional machines.
The pairing process adds another layer. Before any Bluetooth traffic flows, the wallet and app swap public keys out of band using a QR code.
Because the initial key exchange never touches Bluetooth, the Bluetooth chip is never in a position to see plaintext data. Even if that chip were compromised, an attacker would be sitting on a pile of encrypted traffic with no way to unlock it.
Foundation also leaves the door open for purists. Passport Prime lets users disable Bluetooth entirely and fall back to QR, NFC or USB, so nobody is forced onto the wireless path.
From QR codes to quantum resistance
Foundation’s case for QuantumLink draws heavily on its history. The company’s earlier device, the Passport Core, introduced QR air-gapping to Bitcoin self-custody and has since been discontinued.
QuantumLink was publicly introduced on January 23, 2025. Foundation developed the protocol in collaboration with Blockchain Commons during the design phase.
Details on the Passport Prime, which launched with QuantumLink built in, emerged on March 26, 2026.
Herbert, a Bitcoin advocate since 2013, has been explaining the protocol across multiple platforms, including X and CoinDesk.
What this means for self-custody
Community discussions have zeroed in on Bluetooth-related vulnerabilities, and the burden falls on Foundation to show that the hardware separation performs as well in practice as it does on a diagram.