API Reference

Package github.com/itslab-kyushu/sss/sss provides Distribute and Reconstruct functions, which execute distribute and reconstruct procedures defined in the threshold Secret Sharing scheme. It also provides useful structures, Field and Polynomial.

This page explains a basic usage of those functions. See godoc for the detailed information.

Installation

$ go get -d github.com/itslab-kyushu/sss

Example

Compute shares from a secret

Distribute function takes secret, chunk size, the total number of shares, and minimum number of shares to reconstruct the secret, in this order, and returns a slice of shares.

The following example reads a file, creates shares and stores them in JSON format.

secret, err := ioutil.ReadFile("secret-file")
if err != nil {
  return err
}

shares, err := sss.Distribute(secret, chunksize, totalShares, threshold)
if err != nil {
  return err
}

for i, s := range shares {
  data, err := json.Marshal(s)
  if err != nil {
    return err
  }
  filename := fmt.Sprintf("%s.%d.json", "share-", i)
  if err = ioutil.WriteFile(filename, data, 0644); err != nil {
    return err
  }
}

Reconstruct the secret

Reconstruct takes a slice of shares and returns the secret in a slice of bytes.

The following example reads a set of share files, reconstruct the secret, and writes it to a file.

// filenames is a slice of file names of shares.
shares := make([]sss.Share, len(filenames))
for i, f := range filenames {

  data, err := ioutil.ReadFile(f)
  if err != nil {
    return err
  }

  if err = json.Unmarshal(data, &shares[i]); err != nil {
    return err
  }

}

secret, err := sss.Reconstruct(shares)
if err != nil {
  return err
}
return ioutil.WriteFile("secret-file", secret, 0644)