State-of-the-art seed phrase backup.

Penlock is an open-source, cryptographically secure, printable paper-computer. It guides users through secret-splitting their BIP39 seed phrase without an electronic device.

Note from the developer

This is a beta release, exclusively intended for peer-reviewing and early testing. The public release is planned for Q3 2024 and it is likely, but not guaranteed, to be backward-compatible with the present documents. If we break compatibility, this beta-version will still be available at the current address (beta.penlock.io).

Please note that the following pieces are still missing:

Browser compatibility is still being worked on; Safari has known printing issues, while Firefox and Chromium-based browsers are well supported.

Your feedback matters!

Help us shape the future of Penlock: a feedback form is available for early testers!

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Getting things done

Split a Seed Phrase (2-of-3)

Medium

Split a seed phrase into 3 cryptographically secure "shares"; any 2 of these can be used to recover the seed phrase. This is the recommended backup strategy.

You need to print:

Generate a Seed Phrase

Easy

Generate a 12-word seed phrase using real-world, provable randomness.

You need to print:

Advanced Features

Split a Seed Phrase (2-of-M)

Medium

Split a seed phrase into M cryptographically secure "shares"; any 2 of these can be used to recover the seed phrase. Prior experience of the 2-of-3 guide is required.

You need to print:

Split a Seed Phrase (K-of-M)

Difficult

Split a seed phrase into M cryptographically secure "shares"; any K of these can be used to recover the seed phrase. Prior experience of the 2-of-3 guide is required.

You need to print: