SeedSigner extension kit
A smartcard hat for your RPi
€59,99
Unleash the power of your existing Seedsigner with this smartcard kit.
Allow the use of Satochip products directly with your Seedsigner. Manage all your seeds with Seedkeeper, use your Satochip to sign transaction securely.
The kit contains:
- 1 x dual slots smartcard hat for your existing Seedsigner
- 1 x black 3D printed case that fit your Seedsigner and smartcard hat
- 1 x DIY smartcard
Discover SeedSigner
A Bitcoin signing device
SeedSigner is an open-source, do-it-yourself (DIY) Bitcoin signing device designed with security in mind. Unlike traditional hardware wallets, it doesn't store your private keys permanently. Instead, you generate or scan them—often via QR codes—only when you need to sign a transaction. Because the device is stateless and holds no long-term secrets, the risk of theft if it's lost or compromised is significantly reduced.
This stateless approach is powerful, but it also has drawbacks. Each time you want to sign a transaction, you must load your seed onto the device. For users managing multiple wallets—and therefore multiple seeds—this quickly becomes a challenge, making secure and convenient seed management difficult.
The seed storage dilemma
A smartcard approach
The broader problem remains: how can private keys be stored in a way that is secure, resilient, and easy to use?
Different wallets have tried different solutions. SeedQR🔗, for instance, has gained popularity thanks to its speed and convenience compared to traditional seedphrases🔗. Yet, depending solely on SeedQR brings its own concerns around security, durability, and privacy.
A more balanced approach is to store secrets on a PIN-protected Javacard such as Seedkeeper🔗. This method combines strong security with practicality, offering a solution that is affordable, reliable, and accessible for everyday users—without the headaches of juggling multiple seeds or compromising on safety.
Supercharge your SeedSigner with smartcards
Manage all your seeds easily
By supercharging your SeedSigner with smartcard support, you can manage all your seeds with Seedkeeper and even sign your Bitcoin transactions using Satochip.
With this setup, you can:
- Sign transactions and verify PSBTs directly with your Satochip card🔗;
- Sign messages and export xpubs (for both single and multisig setups) with full address explorer integration;
- Manage all your seeds, wallet descriptors and secrets with Seedkeeper🔗 ;
- Use Seedkeeper with Electrum seeds, including support for split passphrases and encrypted QR codes.
Using smartcards with SeedSigner requires just a few adjustments: you'll need a smartcard reader and a dedicated SeedSigner firmware that integrates all Satochip smartcard features.
The good news? This kit includes everything you need to get started.
Ready to start?
Unlock the full potential of your SeedSigner with this complete kit, which includes:
This kit enhances your SeedSigner with a plug-and-play smartcard hat that provides a CCID/PCSC-compatible interface with two slots—ID-1 (standard bank card size) and ID-000 (SIM card size)—plus a convenient USB-C port for powering your device. To keep everything safe, it comes with a matte-black case designed by CryptoGuide🔗 and printed by GoBrrr🔗, precisely crafted to protect your SeedSigner while using the smartcard hat. Completing the package, the included JavaCard smartcard🔗 is fully compatible with both contact and NFC interfaces, shipped unlocked with default keys so you can easily load your favorite applets directly from your SeedSigner.
Useful ressources
How to assemble the smartcard hat
How to flash the DIY compatible smartcard
How to backup an existing SeedQR to Seedkeeper
How to load a seed from Seedkeeper
How to remove an applet from the DIY smartcard
