/// <summary>
/// Удвоить точку на кривой
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public IEllipticCurvePoint Doubling()
{
if (m_Y.Zero)
{
return(GetInfinity());
}
// Исходные координаты
uint[] a = m_a4.m_Value;
uint[] x = m_X.m_Value;
uint[] y = m_Y.m_Value;
uint[] z = m_Z.m_Value;
uint[] modulo = m_Modulo.m_Value;
int maxModuloBitIndex = BigHelper.MaxNonZeroBitIndex(modulo);
int length = modulo.Length;
// Выделим кэш операций умножения
uint[] cache = new uint[length * 2];
uint[] s = new uint[length];
uint[] m = new uint[length];
uint[] x1 = new uint[length];
uint[] y1 = new uint[length];
uint[] z1 = new uint[length];
// Расчитаем m
// Первое слагаемое a*Z1^4
ModuloOperations.Multiply(z, z, modulo, z1, cache);
ModuloOperations.Multiply(z1, z1, modulo, z1, cache);
ModuloOperations.Multiply(z1, a, modulo, z1, cache);
// Второе слагаемое 3*X1^2
ModuloOperations.Multiply(x, x, modulo, m, cache);
ModuloOperations.Multiply(m, 3, modulo, m, cache);
// Результат m = 3*X1^2 + a*Z1^4
ModuloOperations.Addition(m, z1, modulo);
// Расчитаем s = 4*X1*Y1^2
ModuloOperations.Multiply(y, y, modulo, z1, cache);
ModuloOperations.Multiply(z1, x, modulo, s, cache);
ModuloOperations.Multiply(s, 4, modulo, s, cache);
// Расчитаем X3 = m^2 - 2*s
ModuloOperations.Multiply(m, m, modulo, x1, cache);
ModuloOperations.Multiply(s, 2, modulo, y1, cache);
ModuloOperations.Substraction(x1, y1, modulo);
// Расчитаем Y3 = m*(s - X3) - 8*Y1^4
ModuloOperations.Multiply(z1, z1, modulo, z1, cache);
ModuloOperations.Multiply(z1, 8, modulo, z1, cache);
ModuloOperations.Substraction(s, x1, modulo, y1);
ModuloOperations.Multiply(y1, m, modulo, y1, cache);
ModuloOperations.Substraction(y1, z1, modulo);
// Расчитаем Z3 = 2*Y1*Z1
ModuloOperations.Multiply(y, z, modulo, z1, cache);
ModuloOperations.Multiply(z1, 2, modulo, z1, cache);
return(new EllipticCurvePointB(x1, y1, z1, this));
}
/// <summary>
/// Decrements value
/// </summary>
/// <param name="value1">The value to decrement</param>
/// <returns>Decremented value</returns>
public static MIntBig operator --(MIntBig value)
{
if (value as object == null)
{
throw new ArgumentNullException("value");
}
uint[] items = new uint[value.m_Modulo.m_Value.Length];
ModuloOperations.Substraction(value.m_Value.m_Value, 1, value.m_Modulo.m_Value, items);
return(new MIntBig(new IntBig(items), value.m_Modulo));
}
/// <summary>
/// Subtracts a value from another value
/// </summary>
/// <param name="value1">The value to subtract from</param>
/// <param name="value2">The value to subtract</param>
/// <returns>The result of subtracting</returns>
public static MIntBig operator -(MIntBig value1, MIntBig value2)
{
if (value1 as object == null)
{
throw new ArgumentNullException("value1");
}
if (value2 as object == null)
{
throw new ArgumentNullException("value2");
}
if (value1.m_Modulo != value2.m_Modulo)
{
throw new Exception("Modules not equal!");
}
uint[] items = new uint[value1.m_Modulo.m_Value.Length];
ModuloOperations.Substraction(value1.m_Value.m_Value, value2.m_Value.m_Value, value1.m_Modulo.m_Value, items);
return(new MIntBig(new IntBig(items), value1.m_Modulo));
}
/// <summary>
/// Сложить две точки на кривой
/// </summary>
/// <param name="value1"></param>
/// <param name="value2"></param>
/// <returns></returns>
public IEllipticCurvePoint Addition(IEllipticCurvePoint value)
{
EllipticCurvePointB value2 = value as EllipticCurvePointB;
if (value2 as object == null)
{
throw new Exception("Incorrect point type!");
}
if (m_a4 != value2.m_a4 || m_a6 != value2.m_a6 || m_Modulo != value2.m_Modulo)
{
throw new Exception("Incorrect value elliptic curve parameters!");
}
if (Equals(value2))
{
return(Doubling());
}
// Исходные координаты
uint[] a = m_a4.m_Value;
uint[] x1 = m_X.m_Value;
uint[] y1 = m_Y.m_Value;
uint[] z1 = m_Z.m_Value;
uint[] x2 = value2.m_X.m_Value;
uint[] y2 = value2.m_Y.m_Value;
uint[] z2 = value2.m_Z.m_Value;
uint[] modulo = m_Modulo.m_Value;
int maxModuloBitIndex = BigHelper.MaxNonZeroBitIndex(modulo);
int length = modulo.Length;
// Выделим кэш операций умножения
uint[] cache = new uint[length * 2];
// Временные переменные
uint[] u1 = new uint[length];
uint[] u2 = new uint[length];
uint[] s1 = new uint[length];
uint[] s2 = new uint[length];
uint[] xr = new uint[length];
uint[] yr = new uint[length];
uint[] zr = new uint[length];
// Вычислить U1, U2, S1, S2
ModuloOperations.Multiply(z2, z2, modulo, u1, cache);
ModuloOperations.Multiply(z1, z1, modulo, u2, cache);
ModuloOperations.Multiply(u1, z2, modulo, s1, cache);
ModuloOperations.Multiply(u2, z1, modulo, s2, cache);
ModuloOperations.Multiply(u1, x1, modulo, u1, cache);
ModuloOperations.Multiply(u2, x2, modulo, u2, cache);
ModuloOperations.Multiply(s1, y1, modulo, s1, cache);
ModuloOperations.Multiply(s2, y2, modulo, s2, cache);
// Проверим, может расчет
if (Eguals(u1, u2))
{
if (Eguals(s1, s2))
{
return(Doubling());
}
else
{
return(GetInfinity());
}
}
ModuloOperations.Substraction(u2, u1, modulo);
ModuloOperations.Substraction(s2, s1, modulo);
//H^2
ModuloOperations.Multiply(u2, u2, modulo, yr, cache);
//H^3
ModuloOperations.Multiply(yr, u2, modulo, zr, cache);
//R^2
ModuloOperations.Multiply(s2, s2, modulo, xr, cache);
//R^2 - H^3
ModuloOperations.Substraction(xr, zr, modulo);
//U1*H^2
ModuloOperations.Multiply(u1, yr, modulo, yr, cache);
//2*U1*H^2
ModuloOperations.Multiply(yr, 2, modulo, u1, cache);
//X3 = R^2 - H^3 - 2*U1*H^2
ModuloOperations.Substraction(xr, u1, modulo);
//U1*H^2 - X3
ModuloOperations.Substraction(yr, xr, modulo);
//R*(U1*H^2 - X3)
ModuloOperations.Multiply(yr, s2, modulo, yr, cache);
//S1*H^3
ModuloOperations.Multiply(s1, zr, modulo, zr, cache);
//R*(U1*H^2 - X3) - S1*H^3
ModuloOperations.Substraction(yr, zr, modulo);
//Z1*Z2
ModuloOperations.Multiply(z1, z2, modulo, zr, cache);
//Z3 = H*Z1*Z2
ModuloOperations.Multiply(zr, u2, modulo, zr, cache);
return(new EllipticCurvePointB(xr, yr, zr, this));
}