/// <summary>
/// Creates a random polynomial f(x,y) and then to create from it for
/// the i-th player two polynomials : fi(x) = f(x,w^i) and gi(y) = f(w^i,y).
/// </summary>
public static IList <SecretPolynomials> ShareByzantineCase(Zp secret,
int numPlayers, int polynomDeg)
{
if (numPlayers <= 4 * polynomDeg)
{
throw new System.ArgumentException("Cannot use Byzantine algoritm -- numberOfPlayers <= 4*polynomDeg - " + "use regular computation instead");
}
// Creating the Random Polynomial - f(x , y)
// Note : there are (t+1)^2 coefficiet for the polynomial including the free coefficient (the secret)
// first row coef are of (x^0,x^1,x^2,...,x^t)y^0, second row coef are (x^0, x1,...,x^t)y^1 and so forth...
var randomMatrix_f_xy = ZpMatrix.GetRandomMatrix(polynomDeg + 1, polynomDeg + 1, secret.Prime);
randomMatrix_f_xy.SetMatrixCell(0, 0, secret);
var polynomialShares = new List <SecretPolynomials>();
for (int i = 0; i < numPlayers; i++)
{
var pSecret = new SecretPolynomials();
pSecret.Fi_xPolynomial = GenerateF_i_xPolynomial(randomMatrix_f_xy, secret, i);
pSecret.Gi_yPolynomial = GenerateG_i_yPolynomial(randomMatrix_f_xy, secret, i);
polynomialShares.Add(pSecret);
}
return(polynomialShares);
}
/// <summary>
/// Creates a random polynomial f(x,y) and then to create from it for
/// the i-th player two polynomials : fi(x) = f(x,w^i) and gi(y) = f(w^i,y).
/// </summary>
public static IList<SecretPolynomials> ShareByzantineCase(Zp secret,
int numPlayers, int polynomDeg)
{
if (numPlayers <= 4 * polynomDeg)
throw new System.ArgumentException("Cannot use Byzantine algoritm -- numberOfPlayers <= 4*polynomDeg - " + "use regular computation instead");
// Creating the Random Polynomial - f(x , y)
// Note : there are (t+1)^2 coefficiet for the polynomial including the free coefficient (the secret)
// first row coef are of (x^0,x^1,x^2,...,x^t)y^0, second row coef are (x^0, x1,...,x^t)y^1 and so forth...
var randomMatrix_f_xy = ZpMatrix.GetRandomMatrix(polynomDeg + 1, polynomDeg + 1, secret.Prime);
randomMatrix_f_xy.SetMatrixCell(0, 0, secret);
var polynomialShares = new List<SecretPolynomials>();
for (int i = 0; i < numPlayers; i++)
{
var pSecret = new SecretPolynomials();
pSecret.Fi_xPolynomial = GenerateF_i_xPolynomial(randomMatrix_f_xy, secret, i);
pSecret.Gi_yPolynomial = GenerateG_i_yPolynomial(randomMatrix_f_xy, secret, i);
polynomialShares.Add(pSecret);
}
return polynomialShares;
}
private bool IsPublicDataContradictPrivate(SecretPolynomials myRecvPolys, IList<SecretPolynomials> recvPublicPolysList, IList<PlayerNotification> recvComplaintesList, Zp myRecvShare)
{
if ((recvPublicPolysList == null) || (recvPublicPolysList.Count != NumParties))
return true;
var myG_j_w_iValues = myRecvPolys.calculateG_i_yValuesForVerification(NumParties, Prime);
var myF_j_w_iValues = myRecvPolys.CalculateF_i_xValuesForPlayers(NumParties, Prime);
for (int k = 0; k < NumParties; k++)
{
if ((recvComplaintesList[k] != null) && (recvComplaintesList[k].Confirmation == Confirmation.Complaint))
{
var playerKNewPolys = recvPublicPolysList[k];
// Check if the dealer didn't publish all the required data or published a corrupted data
if (!IsSecretPolynomialsLegal(playerKNewPolys))
return true;
// Verify that the public information doesn't contradict itself - check that : f(w^k, w^k) = fk(w^k) = gk(w^k) = f(w^k, w^k)
var playerKNewFk_x_w_iValues = playerKNewPolys.CalculateF_i_xValuesForPlayers(NumParties, Prime);
var playerKNewGk_y_w_iValues = playerKNewPolys.calculateG_i_yValuesForVerification(NumParties, Prime);
if (!playerKNewFk_x_w_iValues[k].Equals(playerKNewGk_y_w_iValues[k]))
return true;
if (k == Party.Id)
{
// Verify that the new public polynomials equals the old polynomials
if (!IsSecretPolynomialsLegal(myRecvPolys) || !myRecvPolys.Equals(playerKNewPolys))
return true;
}
else
{
// Verify that the public information doesn't contradict the old information :
// f(w^j, w^k) = fk(w^j) = gj(w^k) = f(w^j, w^k) && f(w^k, w^j) = fj(w^k) = gk(w^j) = f(w^k, w^j)
if ((!myG_j_w_iValues[k].Equals(playerKNewFk_x_w_iValues[Party.Id])) || (!myF_j_w_iValues[k].Equals(playerKNewGk_y_w_iValues[Party.Id])))
return true;
}
}
}
return false;
}
/// <summary>
/// Checks if the received polynomials are not null, from the right size and have no null elements */
/// </summary>
protected bool IsSecretPolynomialsLegal(SecretPolynomials secretPolynomial)
{
if (secretPolynomial == null)
return false;
else
{
var fi_xPoly = secretPolynomial.Fi_xPolynomial;
var gi_yPoly = secretPolynomial.Gi_yPolynomial;
if (!IsPolynomialLegal(fi_xPoly, PolynomialDeg + 1) || !IsPolynomialLegal(gi_yPoly, PolynomialDeg + 1))
return false;
}
return true;
}
protected virtual void HandleNotDealer(bool isOrigPolyLegal, IList<Coordinate> wrongCoordinatesList, int playerToVerify, Zp recvSecretShare_i, SecretPolynomials secretPoly_i)
{
//// Step 2 - Check and advertise results to players on the bulletin board
//var foundWrongValue1 = !isOrigPolyLegal || (wrongCoordinatesList.Count != 0);
//var complaintValue = new PlayerNotification(foundWrongValue1 ? Confirmation.Complaint : Confirmation.Approval);
//var recvComplaintesList = Sendable.asPlayerNotifications(
// BulletinBoardProtocol.PublishAndRead(complaintValue, Prime, BadPlayers));
//// Count complaints number
//int numOfcomplaints = GetNumberOfComplaints(recvComplaintesList);
//// Step 3 - If there is a need, receive polynomials for the complainig sides and verify it
//// currently check only polynomials - not wrong coordinates
//if (numOfcomplaints != 0)
//{
// // Should get a list of the public polynomials from player 'playerToVerify' - get info from the bulletin board
// var sendablePolysRecv = BulletinBoardProtocol.Read(playerToVerify, Prime);
// IList<SecretPolynomials> recvPublicPolysList1 = null;
// if (sendablePolysRecv != null)
// recvPublicPolysList1 = sendablePolysRecv.asSecretPolynomialsBundle().List;
// if (foundWrongValue1)
// UpdateRecvShare(recvPublicPolysList1, recvSecretShare_i);
// bool foundWrongValue2 = (!isOrigPolyLegal) || IsPublicDataContradictPrivate(secretPoly_i, recvPublicPolysList1, recvComplaintesList, recvSecretShare_i);
// // Check and advertise results to players on the bulletin board
// complaintValue = new PlayerNotification(foundWrongValue2 ? Confirmation.Complaint : Confirmation.Approval);
// recvComplaintesList = Sendable.asPlayerNotifications(
// BulletinBoardProtocol.PublishAndRead(complaintValue, Prime, BadPlayers));
// // Count complaints number
// numOfcomplaints = GetNumberOfComplaints(recvComplaintesList);
// // Step 4 - If there is a need, recieve polynomials for the complainig sides and verify it
// if (numOfcomplaints != 0)
// {
// // Should get a list of the public polynomials from player 'playerToVerify' - get info from the bulletin board
// sendablePolysRecv = BulletinBoardProtocol.Read(playerToVerify, Prime);
// IList<SecretPolynomials> recvPublicPolysList2 = null;
// if (sendablePolysRecv != null)
// recvPublicPolysList2 = sendablePolysRecv.asSecretPolynomialsBundle().List;
// if (foundWrongValue2)
// UpdateRecvShare(recvPublicPolysList2, recvSecretShare_i);
// bool foundWrongValue3 = (!isOrigPolyLegal) || IsPublicDataContradictPrivate(secretPoly_i, recvPublicPolysList2, recvComplaintesList, recvSecretShare_i);
// foundWrongValue3 = foundWrongValue3 || IsNewPublicDataContradictOld(recvPublicPolysList1, recvPublicPolysList2);
// // Check and advertise results to players on the bulletin board
// complaintValue = new PlayerNotification(foundWrongValue3 ? Confirmation.Complaint : Confirmation.Approval);
// recvComplaintesList = Sendable.asPlayerNotifications(
// BulletinBoardProtocol.PublishAndRead(complaintValue, Prime, BadPlayers));
// // Count complaints number
// numOfcomplaints = GetNumberOfComplaints(recvComplaintesList);
// /* Step 5 - Check if there is more than 'polynomialDeg' complaintes or recption timeout occured */
// if (numOfcomplaints > PolynomialDeg)
// {
// // Found a cheater player: playerToVerify - taking its input as zero.
// // Take the zero polynomial as this user input
// recvSecretShare_i.Value = 0;
// RemoveCheaterPlayer(playerToVerify); // don't send and receive from this player anymore...
// }
// }
//}
//throw new NotImplementedException();
}
