What is a Shamir backup?

A Shamir Backup (also known as a Shamir Secret Sharing Scheme) is a way to secure and share a secret using a cryptographic method that allows for the secret to be reconstructed using a specified number of shares. This method provides a higher level of security compared to traditional backups, as the secret is not stored in a single location.  If you don't know what you are doing, you could have your crypto compromised.  Please do your own research.

To create a Shamir Backup:

1. Decide on the number of shares and the number of shares required to reconstruct the secret.

2. Generate a random seed, typically 12 or 24 words, and split the seed into the specified number of shares using a Shamir Secret Sharing algorithm.

3. Store each share in a secure location, such as a physical safe or encrypted digital storage.

To use a Shamir Backup:

1. Retrieve the required number of shares.

2. Reconstruct the seed using the Shamir Secret Sharing algorithm and the retrieved shares.

3. Use the seed to recover the original secret.

Note: It is important to store each share securely and to not lose any of the shares, as it would make it impossible to reconstruct the secret. 

To create a Shamir Backup with 2-of-3 shares, follow these steps:

1. Generate a secret: Choose a random string of characters, such as a phrase or a password, that you want to split into shares. This secret will be your backup data.

2. Split the secret: Use a Shamir Secret Sharing tool to split the secret into three shares, with a threshold of two shares required to reconstruct the secret. Each share will be a unique string of characters, and no share will contain the full secret on its own.

3. Store the shares: Store each share in a secure location, such as a password manager or a physical safe. It's important to keep each share separate and secure, as the secret can only be reconstructed if two of the three shares are available.

To use a Shamir Backup, you need to have at least two of the three shares. Follow these steps:

1. Obtain the shares: Retrieve two of the three shares that you stored.

2. Reconstruct the secret: Use a Shamir Secret Sharing tool to combine the two shares and reconstruct the original secret.

3. Use the secret: Use the secret as you would normally, such as to restore a wallet or access a secure account.

Note: Always make sure to store your shares in secure locations and keep them confidential, as anyone with access to two of the shares can reconstruct the secret.

A Shamir Sharing tool is a software that allows you to divide a secret into multiple parts, known as shares, using a technique called Shamir's Secret Sharing. This allows you to securely store the secret in multiple locations, and only by combining a minimum number of shares (in this case 2 of 3) can the secret be recovered. To use it without the internet, you would need to find a desktop or offline version of the tool, which can be found on various open-source platforms, such as GitHub. After downloading and installing the tool, you can follow the instructions provided to create the shares, store them securely, and recover the secret by combining the necessary number of shares.

To use the Shamir software, you need to follow these steps:

1. Download and install the software on your device.
2. Launch the software and select "Create a Shamir Secret Sharing Scheme."
3. Input the secret you want to share and specify the number of shares you want to generate and the number of shares required to reconstruct the secret.
4. If you have specified 2 of 3 shares as the requirement for reconstruction, the software will generate three shares.
5. Store the shares in a secure location and distribute them as desired.
6. To reconstruct the secret, you need to input the required number of shares into the software.
7. The software will then calculate the original secret and display it.

Note: You can use the Shamir software offline if you have it installed on your device.