github.com/posener/sharedsecret

sharedsecret

Package sharedsecret is implementation of Shamir's Secret Sharing algorithm.

Shamir's Secret Sharing is an algorithm in cryptography created by Adi Shamir. It is a form of secret sharing, where a secret is divided into parts, giving each participant its own unique part. To reconstruct the original secret, a minimum number of parts is required. In the threshold scheme this number is less than the total number of parts. Otherwise all participants are needed to reconstruct the original secret. See wiki page.

Examples

Distribute

With the Distribute function, a given secret can be distributed to shares.

secret := big.NewInt(120398491412912873)

// Create 5 shares that 3 or more of them can recover the secret.
shares := Distribute(secret, 5, 3)

// We can recover from only 3 (or more) shares:
recovered := Recover(shares[1], shares[3], shares[0])

fmt.Println(recovered)

Output:

120398491412912873

New

With the New function, a random secret is generated and distributed into shares. Both the secret and the shares are returned.

// Create 5 shares that 3 or more of them can recover the secret.
shares, secret := New(5, 3)

// Now we should distribute the shares to different parties and forget about the shares and
// secret. Once the original secret is needed, at least 3 shares should be used in order to
// recover it:

// We can't recover from only 2 shares:
wrong := Recover(shares[1], shares[3])

// We can recover from only 3 (or more) shares:
correct := Recover(shares[1], shares[3], shares[0])

fmt.Println(secret.Cmp(wrong) != 0, secret.Cmp(correct) == 0)

Output:

true true

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