Python Integer.set方法代码示例

# 需要导入模块: from Cryptodome.Math.Numbers import Integer [as 别名]
# 或者: from Cryptodome.Math.Numbers.Integer import set [as 别名]
def lucas_test(candidate):
    """Perform a Lucas primality test on an integer.

    The test is specified in Section C.3.3 of `FIPS PUB 186-4`__.

    :Parameters:
      candidate : integer
        The number to test for primality.

    :Returns:
      ``Primality.COMPOSITE`` or ``Primality.PROBABLY_PRIME``.

    .. __: http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf
    """

    if not isinstance(candidate, Integer):
        candidate = Integer(candidate)

    # Step 1
    if candidate.is_even() or candidate.is_perfect_square():
        return COMPOSITE

    # Step 2
    def alternate():
        sgn = 1
        value = 5
        for x in xrange(10):
            yield sgn * value
            sgn, value = -sgn, value + 2

    for D in alternate():
        js = Integer.jacobi_symbol(D, candidate)
        if js == 0:
            return COMPOSITE
        if js == -1:
            break
    else:
        return COMPOSITE
    # Found D. P=1 and Q=(1-D)/4 (note that Q is guaranteed to be an integer)

    # Step 3
    # This is \delta(n) = n - jacobi(D/n)
    K = candidate + 1
    # Step 4
    r = K.size_in_bits() - 1
    # Step 5
    # U_1=1 and V_1=P
    U_i = Integer(1)
    V_i = Integer(1)
    U_temp = Integer(0)
    V_temp = Integer(0)
    # Step 6
    for i in xrange(r - 1, -1, -1):
        # Square
        # U_temp = U_i * V_i % candidate
        U_temp.set(U_i)
        U_temp *= V_i
        U_temp %= candidate
        # V_temp = (((V_i ** 2 + (U_i ** 2 * D)) * K) >> 1) % candidate
        V_temp.set(U_i)
        V_temp *= U_i
        V_temp *= D
        V_temp.multiply_accumulate(V_i, V_i)
        if V_temp.is_odd():
            V_temp += candidate
        V_temp >>= 1
        V_temp %= candidate
        # Multiply
        if K.get_bit(i):
            # U_i = (((U_temp + V_temp) * K) >> 1) % candidate
            U_i.set(U_temp)
            U_i += V_temp
            if U_i.is_odd():
                U_i += candidate
            U_i >>= 1
            U_i %= candidate
            # V_i = (((V_temp + U_temp * D) * K) >> 1) % candidate
            V_i.set(V_temp)
            V_i.multiply_accumulate(U_temp, D)
            if V_i.is_odd():
                V_i += candidate
            V_i >>= 1
            V_i %= candidate
        else:
            U_i.set(U_temp)
            V_i.set(V_temp)
    # Step 7
    if U_i == 0:
        return PROBABLY_PRIME
    return COMPOSITE

# 需要导入模块: from Cryptodome.Math.Numbers import Integer [as 别名]
# 或者: from Cryptodome.Math.Numbers.Integer import set [as 别名]
class EccPoint(object):
    """A class to abstract a point over an Elliptic Curve.

    :ivar x: The X-coordinate of the ECC point
    :vartype x: integer

    :ivar y: The Y-coordinate of the ECC point
    :vartype y: integer
    """

    def __init__(self, x, y):
        self._x = Integer(x)
        self._y = Integer(y)

        # Buffers
        self._common = Integer(0)
        self._tmp1 = Integer(0)
        self._x3 = Integer(0)
        self._y3 = Integer(0)

    def set(self, point):
        self._x = Integer(point._x)
        self._y = Integer(point._y)
        return self

    def __eq__(self, point):
        return self._x == point._x and self._y == point._y

    def __neg__(self):
        if self.is_point_at_infinity():
            return self.point_at_infinity()
        return EccPoint(self._x, _curve.p - self._y)

    def copy(self):
        return EccPoint(self._x, self._y)

    def is_point_at_infinity(self):
        return not (self._x or self._y)

    @staticmethod
    def point_at_infinity():
        return EccPoint(0, 0)

    @property
    def x(self):
        if self.is_point_at_infinity():
            raise ValueError("Point at infinity")
        return self._x

    @property
    def y(self):
        if self.is_point_at_infinity():
            raise ValueError("Point at infinity")
        return self._y

    def double(self):
        """Double this point (in-place operation).

        :Return:
            :class:`EccPoint` : this same object (to enable chaining)
        """

        if not self._y:
            return self.point_at_infinity()

        common = self._common
        tmp1 = self._tmp1
        x3 = self._x3
        y3 = self._y3

        # common = (pow(self._x, 2, _curve.p) * 3 - 3) * (self._y << 1).inverse(_curve.p) % _curve.p
        common.set(self._x)
        common.inplace_pow(2, _curve.p)
        common *= 3
        common -= 3
        tmp1.set(self._y)
        tmp1 <<= 1
        tmp1.inplace_inverse(_curve.p)
        common *= tmp1
        common %= _curve.p

        # x3 = (pow(common, 2, _curve.p) - 2 * self._x) % _curve.p
        x3.set(common)
        x3.inplace_pow(2, _curve.p)
        x3 -= self._x
        x3 -= self._x
        while x3.is_negative():
            x3 += _curve.p

        # y3 = ((self._x - x3) * common - self._y) % _curve.p
        y3.set(self._x)
        y3 -= x3
        y3 *= common
        y3 -= self._y
        y3 %= _curve.p

        self._x.set(x3)
        self._y.set(y3)
        return self

#.........这里部分代码省略.........