Package org.magmacollective.darkcrystal.secretsharingwrapper

Class SecretSharingWrapper

  • public class SecretSharingWrapper
extends java.lang.Object
    Wrapper around 'sss' secrets library, providing extra features Dark Crystal Distributed Key Backup

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  SecretSharingWrapper.SecretWithLabel
      Class for packing a secret together with a descriptive label

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static byte[] combine​(java.util.List<byte[]> shares)
      Attempt to recover the secret by combining shares created with the share method
      static SecretSharingWrapper.SecretWithLabel decodeSecretWithLabel​(byte[] packedSecret)
      Decode a packed secret
      static int defaultThreshold​(int numberCustodians)
      Give a recommended threshold value, given the number of custodians
      static boolean isShare​(byte[] share)
      Validate whether a given byte array could be a shard by checking its length
      static boolean isSignedShare​(byte[] signedShare)
      Validate whether a given byte array could be a signed share by checking its length
      static java.util.List<byte[]> partialShuffleList​(java.util.List<byte[]> list, int elementsToTake)
      Partially shuffle a list of byte arrays, randomly selecting the given number of entries This is used to randomise the index value of the shares
      static java.util.List<byte[]> share​(byte[] secret, int n, int k)
      Create shares for a secret of any length
      static java.util.List<byte[]> shareAndSign​(byte[] secret, int n, int k, java.security.PrivateKey privateKey)
      A convenience method to create shares and sign them with a given secret key
      static int thresholdSanity​(int threshold, int numberCustodians)
      Gives a threshold sanity factor, given a threshold and number of custodians 0 is ideal.
      static byte[] verifyAndCombine​(java.util.List<byte[]> signedShares, java.security.PublicKey publicKey)
      Convenience method to verify a list of shares containing signates and combine them if successful.
      static byte[] zeroPad​(byte[] input, int padLength)
      Pad the secret with zeros to the given length.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • decodeSecretWithLabel

        public static SecretSharingWrapper.SecretWithLabel decodeSecretWithLabel​(byte[] packedSecret)
                                                                  throws com.google.protobuf.InvalidProtocolBufferException
        Decode a packed secret
        Parameters:
        packedSecret - A secret message previously encoded with `secretWithLabel.encode()`
        Returns:
        a secret object
        Throws:
        com.google.protobuf.InvalidProtocolBufferException - If there was a problem decoding

      • partialShuffleList

        public static java.util.List<byte[]> partialShuffleList​(java.util.List<byte[]> list,
                                                        int elementsToTake)
        Partially shuffle a list of byte arrays, randomly selecting the given number of entries This is used to randomise the index value of the shares
        Parameters:
        list - to be shuffled
        elementsToTake - the number of entries to randomly select
        Returns:
        a random subset of the given list

      • share

        public static java.util.List<byte[]> share​(byte[] secret,
                                           int n,
                                           int k)
        Create shares for a secret of any length
        Parameters:
        secret -
        n - the number of shares to create
        k - the threshold
        Returns:
        a list of shares

      • combine

        public static byte[] combine​(java.util.List<byte[]> shares)
                      throws java.security.GeneralSecurityException
        Attempt to recover the secret by combining shares created with the share method
        Parameters:
        shares - a list of shares
        Returns:
        the secret, if successful
        Throws:
        java.security.GeneralSecurityException

      • shareAndSign

        public static java.util.List<byte[]> shareAndSign​(byte[] secret,
                                                  int n,
                                                  int k,
                                                  java.security.PrivateKey privateKey)
                                           throws java.lang.Exception
        A convenience method to create shares and sign them with a given secret key
        Parameters:
        secret -
        n - the number of shares
        k - the threshold
        privateKey - an EdDSA signing private key
        Returns:
        a list of signed shares
        Throws:
        java.lang.Exception

      • verifyAndCombine

        public static byte[] verifyAndCombine​(java.util.List<byte[]> signedShares,
                                      java.security.PublicKey publicKey)
                               throws java.lang.Exception
        Convenience method to verify a list of shares containing signates and combine them if successful.
        Parameters:
        signedShares - a list of shares containing signatures
        publicKey - an EdDSA public signing key
        Returns:
        the secret, if successful
        Throws:
        java.lang.Exception

      • isShare

        public static boolean isShare​(byte[] share)
        Validate whether a given byte array could be a shard by checking its length
        Parameters:
        share - a byte array which may be a shard
        Returns:
        true if the length is ok

      • isSignedShare

        public static boolean isSignedShare​(byte[] signedShare)
        Validate whether a given byte array could be a signed share by checking its length
        Parameters:
        signedShare -
        Returns:
        true if the length is ok

      • zeroPad

        public static byte[] zeroPad​(byte[] input,
                             int padLength)
        Pad the secret with zeros to the given length. If the secret is longer than the given length, it will pad to the nearest multiple of the given length.
        Parameters:
        input - the secret of any length
        padLength - the desired length
        Returns:
        the zero padded result

      • defaultThreshold

        public static int defaultThreshold​(int numberCustodians)
        Give a recommended threshold value, given the number of custodians
        Parameters:
        numberCustodians -
        Returns:
        a recommended threshold value

      • thresholdSanity

        public static int thresholdSanity​(int threshold,
                                  int numberCustodians)
        Gives a threshold sanity factor, given a threshold and number of custodians 0 is ideal. Positive values represent the level of danger of loosing access to the secret. Negative values represent the level of danger of an attacker gaining the secret.
        Parameters:
        threshold -
        numberCustodians -