Adept Secret Sharing (ADSS)

A CLI tool and library implementation of adept secret sharing (ADSS) as described by Bellare, Dai and Rogaway in Reimagining Secret Sharing: Creating a Safer and More Versatile Primitive by Adding Authenticity, Correcting Errors, and Reducing Randomness Requirements.

Usage

CLI

Install by downloading pre-built binaries on the releases page or it install from source with go install github.com/jakecraige/adss.

# Split the secret into a 2-of-3 sharing. First we create a file with the
# secret, it can be of any type, not just txt.
$ echo "some secret" > /tmp/secret.txt
$ adss split -threshold 2 -count 3 -out-dir /tmp -secret-path secret.txt
Share written to: tmp/share-0.json
Share written to: tmp/share-1.json
Share written to: tmp/share-2.json
Complete.

# We can recover by providing all shares. It prints to stdout in base64 by
# default, so we decode it with base64 for this example.
$ adss recover --share-paths /tmp/share-0.json,/tmp/share-1.json,/tmp/share-2.json | base64 -d
some secret

# We can also store the result in a file
$ adss recover --share-paths /tmp/share-0.json,/tmp/share-1.json,/tmp/share-2.json -out-path /tmp/recovered-secret.txt
$ cat /tmp/recovered-secret.txt
some secret

# We can also recover by providing only two
$ adss recover --share-paths /tmp/share-0.json,/tmp/share-1.json | base64 -d
some secret

# If we manually modify the secret value of one of the shares and attempt
# recovery, we are warned about the invalid share but we still recover it.
$ adss recover --share-paths /tmp/share-0.json,/tmp/share-1.json,/tmp/share-2-modified.json | base64 -d
WARN: Invalid share at ./tmp/share-2-modified.json
some secret

Library

// Split the secret into shares. The shares can be json serialized with the
// golang marshaller to be persisted on disk.
as := adss.NewAccessStructure(2, 3)
secret := []byte("the secret")
ad := []byte("the associated data")
shares, err := adss.Share(as, secret, ad)
if err != nil {
  return err
}

// Given a set of shares, attempt to recover the secret. If it can be recovered
// it returns the secret and the set of shares that were valid inputs. If it
// cannot be recovered, an error is returned.
secret, validShares, err := adss.Recover(shares)
if err != nil {
  return err
}

fmt.Printf("%s", secret)
if len(validShares) < len(shares) {
  fmt.Println("Some shares were invalid")
}

Security

This is a work-in-progress implementation and should not be used in any production systems. It does not currently match the paper so it does not provide many of the guarantees required by ADSS. It has also received no security reviews so it should not be trusted until it has.