What is Seedmate?

Maybe we should start with what it’s NOT.

Seedmate is not another hardware wallet. It cannot connect to the internet — no PC, no phone, no software to install.

Seedmate is an air-gapped, standalone BIP39 calculator. 

It was designed specifically to fill the security gaps left behind by most hardware wallets. Seedmate doesn’t replace your hardware wallet — it complements it. 

Self-custody is about keeping a secret safe: safe from loss, safe from prying eyes. 

Firstly, you don’t trust a third party to generate a secret for you. You create it yourself. With Seedmate you can generate mnemonics with real-world randomness: dice, coins, words and poker cards. 

Typing words is the most transparent and trustless method, you pick 24 words and it adjusts  the last one to meet the checksum rules. Just make sure that you shuffle them properly and pull them out blindly.

Secondly, Seedmate lets you mix randomness from different physical sources for maximum entropy. Inputs and outputs are standard BIP39 mnemonics. You can type them using the on-screen keyboard or via an SD card. The SD card option is provided to simplify operations — not for long-term storage — and should be wiped after usage for security, keep it analog!

Thirdly, Seedmate allows you to create advanced recovery schemes, like ‘2 out of 3’.

Your secret is divided into three parts: finding a single part reveals zero bits of information about your secret. Yet, combining any two parts fully recovers it. This gives you both redundancy and security — keeping your secret safe from loss, and safe from prying eyes.

Seedmate achieves this using either XOR logic or Shamir’s Secret Sharing.

• XOR is compatible with other devices, but is limited to 2-of-3 schemes.

• Shamir allows custom, flexible schemes up to 6-of-9.

Because Shamir uses a custom implementation, relying solely on hardware could be a risk if the device is lost. To eliminate that risk, Seedmate includes a standalone, offline HTML tool that replicates every single feature. You can download it, run it on an air-gapped machine, and verify or recover your secrets anytime.

Lastly, Seedmate provides built-in obfuscation functions.

Rather than storing a clear-text copy of your secret, you can apply reversible transformations to it. If someone finds your backup, they won't gain access to your funds unless they know the exact reverse logic.

For example, you can shift every word in your seed by “N” positions. The result is a completely different, valid BIP39 mnemonic.

You can then load this obfuscated seed with a small amount of funds to act as a decoy or as your 'canary in a coal mine'. If those funds ever move, you know immediately that your physical backup has been compromised. 

This decoy/canary strategy can also be used with the recovery schemes mentioned before, as all parts are valid BIP39 seeds.

Seedmate is a personal project engineered in Spain. The hardware consists of 2 boards: a custom-designed processor board powered by a PIC32, paired with a commercial display and SD module.

The software is completely open-source, written from scratch in C code plus a few libraries for SHA256, QR code generation, and Shamir arithmetic.

Seedmate is stateless, it fully clears when powered off. No seeds can be stored inside the device.

Seedmate overview video