private static CombinedSecret Combine(IEnumerable <SecretShare> shares, Diffuser diffuser)
{
var allShares = shares.ToArray();
if (allShares.Length == 0)
{
throw new SecretSplitterException("You must provide at least one secret share (piece).");
}
var expectedShareType = allShares[0].ShareType;
if (!allShares.All(s => s.ShareType == expectedShareType))
{
throw new SecretSplitterException("Secret shares (pieces) must be be of the same type.");
}
var firstInvalidShare = allShares.FirstOrDefault(s => (s.ShareType != SecretShareType.Unknown) && !s.HasValidChecksum);
if (firstInvalidShare != null)
{
throw new InvalidChecksumShareException(firstInvalidShare.ParsedValue);
}
var secretCoefficient = LagrangeInterpolator.EvaluateAtZero(allShares.Select(s => s.Point));
var scrambledValue = secretCoefficient.PolynomialValue;
var unscrambledValue = diffuser.Unscramble(scrambledValue, scrambledValue.ToByteArray().Length);
var recoveredSecret = unscrambledValue.ToUnsignedBigEndianBytes();
return(new CombinedSecret(allShares[0].ShareType, recoveredSecret));
}
public static byte[] Combine(IEnumerable <FiniteFieldPoint> points)
{
var allShares = points.ToArray();
if (allShares.Length == 0)
{
throw new ArgumentException("You must provide at least one secret share (piece).", nameof(points));
}
var secretCoefficient = LagrangeInterpolator.EvaluateAtZero(allShares);
var scrambledValue = secretCoefficient.PolynomialValue;
var unscrambledValue = DefaultDiffuser.Unscramble(scrambledValue, scrambledValue.ToByteArray().Length);
return(unscrambledValue.ToUnsignedBigEndianBytes());
}
private static CombinedSecret Combine(IEnumerable <SecretShare> shares, Diffuser diffuser)
{
var allShares = shares.ToArray();
if (allShares.Length == 0)
{
throw new SecretSplitterException("You must provide at least one secret share (piece).");
}
int expectedShareLength = allShares[0].ParsedValue.Substring(allShares[0].ParsedValue.LastIndexOf('-') + 1).Length;
if (!allShares.All(s => s.ParsedValue.Substring(s.ParsedValue.LastIndexOf('-') + 1).Length == expectedShareLength))
{
throw new SecretSplitterException("Secret shares (pieces) must be be of the same size.");
}
var expectedShareType = allShares[0].ShareType;
if (!allShares.All(s => s.ShareType == expectedShareType))
{
throw new SecretSplitterException("Secret shares (pieces) must be be of the same type.");
}
var firstInvalidShare = allShares.FirstOrDefault(s => (s.ShareType != SecretShareType.Unknown) && !s.HasValidChecksum);
if (firstInvalidShare != null)
{
throw new InvalidChecksumShareException(firstInvalidShare.ParsedValue);
}
var secretCoefficient = LagrangeInterpolator.EvaluateAtZero(allShares.Select(s => s.Point));
var scrambledValue = secretCoefficient.PolynomialValue;
var unscrambledValue = diffuser.Unscramble(scrambledValue, expectedShareLength / 2);
var recoveredSecret = unscrambledValue.ToUnsignedBigEndianBytes();
int paddingNeeded = expectedShareLength / 2 - recoveredSecret.Length;
if (paddingNeeded > 0)
{
var padBytes = new byte[paddingNeeded];
var newArray = new byte[paddingNeeded + recoveredSecret.Length];
Array.Copy(padBytes, 0, newArray, 0, paddingNeeded);
Array.Copy(recoveredSecret, 0, newArray, paddingNeeded, recoveredSecret.Length);
recoveredSecret = newArray;
}
return(new CombinedSecret(allShares[0].ShareType, recoveredSecret));
}