Class GF256

Initialize new element.

The value given is modulo reduced so the following holds:

>>> GF256(1) == GF256(257)
True

Overrides: object.__init__

Add this and another GF256 element.

>>> GF256(0x01) + GF256(0x01)
[0]
>>> GF256(0x01) + GF256(0x02)
[3]

Adding integers works too, the other operand is coerced into a GF256 element automatically:

>>> GF256(0x01) + 1
[0]

Add this and another number (reflected argument version).

other is not Share, otherwise Share.__add__() would have been called, and other is not a GF256, otherwise GF256.__add__() would have been called.

Subtract this and another GF256 element.

Addition is its own inverse in GF(2^8) and so this is the same as __add__.

Exclusive-or.

This is just addition for GF256 elements.

Multiply this and another number (reflected argument version).

other is not Share, otherwise Share.__mul__() would have been called, and other is not a GF256, otherwise GF256.__mul__() would have been called.

Invertion.

Raises ZeroDivisionError if trying to inverse the zero element.

repr(x)

Overrides: object.__repr__

(inherited documentation)

str(x)

Overrides: object.__str__

(inherited documentation)

Equality testing.

Testing for equality with integers works as expected:

>>> GF256(10) == 10
True

Overrides: object.__hash__

Truth value testing.

Returns False if this element is zero, True otherwise. This allows GF256 elements to be used directly in Boolean formula:

>>> bool(GF256(0))
False
>>> bool(GF256(1))
True
>>> x = GF256(1)
>>> not x
False