Hey, we have been building Keycard as an open-source, JavaCard hardware wallet for a couple of years.

Now we’ve opened pre-orders for our new product Keycard Shell, which turns any Keycard into a fully-fledged, open-source hardware wallet.

What makes Keycard Shell unique from the sea of hardware wallets today?

The problem: Today’s common dual-chip designs export keys to a general-purpose MCU (and have been hacked - see Safe 3). Our Shell solution:

• Dedicated Secure Chip (Java Card): All transactions are signed inside a battle-tested, non-upgradable Java Card secure element – the same EAL6+ tech used in bank cards since the ’90s; one chip per Keycard
• Radical Open Source: Hardware & software are MIT-licensed – schematics, PCB layouts, BOM, Java Card applet, CAD files… audit, modify, even 3D-print your own case

Keycard Shell features

• 100% open source: transparent for you to build on, audit, and modify
• Unlimited Keys on Unlimited Cards: use multiple seeds or create secure backup cards; even ditching steal/paper backup for storing 10 cards in different locations (secured by PIN)
• Duress PIN: enter a second PIN under coercion to reveal a decoy wallet
• Air-Gapped QR Signing: sign offline with Shell’s camera & QR; no radio technology on board; USB exists for updates, and can be turned off
• Universal Compatibility: works with UniSat, BlueWallet, Sparrow, BackPack, imToken & 10+ more via BC UR and ERC-4527
• Future-Proof Design: replaceable Nokia BL-4C battery & modular cards for emerging crypto standards

As always, let us know your opinion! Check out our blog for a deep dive into thread scenarios and security trade-offs, and early prototypes.

And, we are taking pre-orders (w/ 50eur off), so feel free to check out https://keycard.tech