public static byte[] decrypt(BFCText c, BFUserPrivateKey sk)
{
BFMasterPublicKey msk = sk.Param;
Pairing e = msk.Pairing;
//e(sQ,U), sQ is the user private key
FieldElement temp = e.Compute(sk.Key, c.U);
//sigma = V xor hash(temp)
byte[] hash = BFUtil.HashToLength(temp.ToUByteArray(), c.V.Length); //This could fail
byte[] sigma = BFUtil.XorTwoByteArrays(c.V, hash);
hash = BFUtil.HashToLength(sigma, c.W.Length);
byte[] m = BFUtil.XorTwoByteArrays(hash, c.W);
//sigma||m
byte[] toHash = new byte[sigma.Length + m.Length];
Array.Copy(sigma, 0, toHash, 0, sigma.Length);
Array.Copy(m, 0, toHash, sigma.Length, m.Length);
//hash(sigma||m) to biginteger r;
Field field = e.Curve2.Field;
BigInt r = BFUtil.HashToField(toHash, field);
if (c.U.Equals(e.Curve2.Multiply(msk.P, r)))
{
return(m);
}
else
{
return(null);
}
}
public KeysController()
{
TatePairing e = Predefined.ssTate();
BigInt s = new BigInt("505589879806357574715819689796588537146433291440", 10);
BFMasterPrivateKey masterPrivate = new BFMasterPrivateKey(s);
BigInt xP = new BigInt("4291662186182105785020055031256275922735182686564035226466395653970413755358824903482223509624549595190077490704367257937172972896431165061643256253841639", 10);
BigInt yP = new BigInt("4734655302033019638724717069550998600270840147458147624263679086394750166097273830456518097912007100893265204858608788227968249694875877762941090121639110", 10);
BigInt xPpub = new BigInt("3321521420324942690122656396767763795495870232445101779865981146134484022298665464121724898190544088107820667943606314446170142017782563402275554873870099", 10);
BigInt yPpub = new BigInt("5811060153287472925206265749794945978469077668029247862550354611572579518279518356217273453987945241447730233617290283194068671621572534510817890943208269", 10);
Point P = new Point(xP, yP);
Point Ppub = new Point(xPpub, yPpub);
BFMasterPublicKey masterPublic = new BFMasterPublicKey(e, P, Ppub);
master = new KeyPair(masterPublic, masterPrivate);
}
public static KeyPair Setup(Pairing e, Random rnd)
{
Point P = e.Curve2.RandomPoint(rnd);
BigInt s = new BigInt(e.GroupOrder.BitLength(), rnd);
while (s.CompareTo(e.GroupOrder) >= 0)
{
s = s.ShiftRight(1);
}
Point Ppub = e.Curve2.Multiply(P, s);
BFMasterPublicKey pk = new BFMasterPublicKey(e, P, Ppub);
BFMasterPrivateKey sk = new BFMasterPrivateKey(s);
//return new KeyPair(pk, sk);
return(new KeyPair(null, null));
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var mappedObj = new BFUserPrivateKey();
//get an array of the object's props so I can check if the JSON prop s/b mapped to it
var objProps = objectType.GetProperties().Select(p => p.Name.ToLower()).ToArray();
Point pPrivate, pPoint, pPub;
pPub = pPrivate = pPoint = null;
TatePairing e = null;;
BFMasterPublicKey pKey;
bool rPPrivate, rPairing, rP, rPPub, rKey, rParam;
rPPub = rPairing = rP = rPPrivate = rKey = rParam = false;
//loop through my JSON string
while (reader.Read())
{
//if I'm at a property...
if (reader.TokenType == JsonToken.PropertyName)
{
//convert the property to lower case
string readerValue = reader.Value.ToString().ToLower();
if (readerValue == "key") //We are expecting point with X and Y coordinates
{
pPrivate = ReadPoint(reader);
rPPrivate = true;
rKey = true;
}
else if (readerValue == "param") //We are expecting a pairing a 2 points
{
while (reader.Read() && rParam == false)
{
if (reader.TokenType == JsonToken.PropertyName)
{
string rValue = reader.Value.ToString().ToLower();
if (rValue == "pairing")
{
e = ReadPairing(reader);
rPairing = true;
}
else if (rValue == "p")
{
pPoint = ReadPoint(reader);
rP = true;
}
else if (rValue == "ppub")
{
pPub = ReadPoint(reader);
rPPub = true;
}
}
if (rP && rPPub && rPairing)
{
rParam = true;
}
}
}
}
if (rParam && rKey)
{
pKey = new BFMasterPublicKey(e, pPoint, pPub);
while (reader.Read())
{
reader.Read();
}
return(new BFUserPrivateKey(pPrivate, pKey));
}
}
return(mappedObj);
}
