About Shamir Backup

Splitting The Secret

The case for Shamir Backup with the Cryptosteel Capsule


The usual approach to protecting digital assets is redundant backups, but when the asset itself is of significant value and high liquidity, there is a substantial risk of a backup custodian absconding with the asset.

The cryptographic secret-sharing scheme created by Adi Shamir is an ingenious way to help protect data.

The Shamir Backup system has revolutionized the Cryptocurrency world by creating a new standard of Master Seed protection.

By splitting your recovery seed up into independent parts called shares and requiring a certain minimum of shares to access the Master Seed, Shamir Backup has become one of the best methods for securing your data.

How Shamir's secret sharing works

Shamir’s secret-sharing provides a better mechanism for backing up secrets by distributing custodianship among a number of trusted parties in a manner that can prevent loss even if one or a few of those parties become compromised.

You may shield important information using Shamir Backup, which is supported by the Capsule. The master secret that you are protecting might never be compromised even in cases of aggressive acts including but not limited to theft, bribery, vandalism and violence where the knowledge of fewer than the required number of shares is discovered.

Cryptosteel Capsules will be shipped in enough packs to ensure you have a Cryptosteel Capsule for each share.  Currently we offer 3 and 5 share bundles however you can add up to a maximum of 16 shares.

Shamir backup is unique in that the first three words of each recovery share will be the same.

About Thresholds

The threshold is the predetermined number of shares necessary to recover a wallet. Any of the unique shares can be used to recover a wallet, as long as it fulfills the threshold requirement. The order of shares is not important.

When generating a new wallet, you set the threshold in accordance with your needs. If you create a Shamir backup consisting of three recovery shares and set the threshold to "2/3", you will need any two of the three shares to reconstruct the wallet.

You can also set the threshold to "3/3", which will then enable you to recover the wallet if all three shares are used.

It is not possible to set the threshold to just one share.

Shamir Secret Sharing

Shamir SLIP-39 Features

  • Redundant Security

    Up to 16 recovery shares

  • Easy to manage

    Choose your threshold

  • Independence

    Autonomous control of assets


  • Extra security

    Eliminated risk of loss or theft

  • Recovery

    Administrative control of master seed

  • Extremely Durable

    Fireproof up to 1400C/2500F. Shockproof. Waterproof. Stainless.

Cryptosteel Capsule Components
Cryptosteel Capsule Australia

Capsule Specifications

  • Dimensions and Weight

    Weight (Full Package): 515 g
    Size: 255 x 185 x 25 mm

  • Forged from Stainless Steel

    Capsule: German AISI 303 Stainless
    Tiles: German AISI 304 Stainless

  • Secret and Key Compatibility

    FIPS PUB 186-4: Digital Signature Standard (DSS)
    FIPS PUB 197: Advanced Encryption Standard (AES)
    BIP32 & SLIP39

Shamir Shares
Shamir Shares

About Recovery Shares

Recovery shares bear some similarities to the BIP39 standard recover share. A recovery share is a sequence of 20 or 33 English words carrying a part of the cryptographic secret. Combining the necessary number (threshold) of shares creates the master secret (seed) needed to recover a wallet.

Trezor Suite will automatically initiate a device with Shamir backup using 20-word shares (128-bit strength). To initialize the device using 33-word shares (256-bit strength) you can configure the strength of the shares during the initialization process.

When creating a wallet with Shamir Backup as implemented in Trezor, the user chooses the number of shares to be generated. The number of shares can range from 1 to a maximum of 16. The set we sell are for 3 and 5 shares.

Shamir backup is unique in that the first three words of each recovery share will be the same.

Shamir backup key steps

1. Choose the number of shares you want to generate.

2. Decide how many shares you want to use for recovery.

3. Distribute those shares among trusted family members or friends, Will executors or secure geographic locations.

4. Sleep peacefully knowing that your recovery seed is protected from a single point of loss or theft.

Further Resources