public static UInt16 Decrypt(ElGamalKey key, KeyValuePair <ushort, ushort> decrypted)
{
var apx = (UInt16)PrimitiveUtilities.ModularPower(decrypted.Key, key.P - 1 - key.X, key.P);
var bapx = (UInt16)((decrypted.Value * apx) % key.P);
return(bapx);
}
public static KeyValuePair <UInt16, UInt16> EncryptKey(ElGamalKey key, UInt16 value)
{
Random random = new Random();
var k = random.Next(1, key.P - 1);
var a = (UInt16)PrimitiveUtilities.ModularPower(key.G, k, key.P);
var b = (UInt16)PrimitiveUtilities.ModularPower(key.Y, k, key.P);
var c = (b * value) % key.P;
return(new KeyValuePair <ushort, ushort>(a, (UInt16)c));
}
public static ElGamalKey GenerateKeysWithDefaultP(UInt16 p = 59)
{
var random = new Random();
UInt16 x = (UInt16)random.Next(2, p);
UInt16 g = PrimitiveUtilities.GetRandomPremetiveRoot(p);
UInt16 y = (UInt16)PrimitiveUtilities.ModularPower(g, x, p);
return(new ElGamalKey
{
X = x,
Y = y,
G = g,
P = p
});
}
public static ElGamalKey GenerateKeys()
{
var random = new Random();
var list = FileReader.ReadFromFileListUInt16(fileName);
var indexOfP = random.Next(list.Count);
UInt16 p = list[indexOfP];
UInt16 x = (UInt16)random.Next(2, p);
UInt16 g = PrimitiveUtilities.GetPremetiveRoot(p);
UInt16 y = (UInt16)PrimitiveUtilities.ModularPower(g, x, p);
return(new ElGamalKey
{
X = x,
Y = y,
G = g,
P = p
});
}