Question

执行此代码时：

Dim bytearray() As Byte = System.IO.File.ReadAllBytes("C:\Users\Fery Ferdiansyah\Desktop\asd\asd.txt")
Dim key() As Byte = System.Text.Encoding.UTF8.GetBytes("swagger")
Dim bf As New blowfish2(key)

此函数中的此语法y = S(0, a) + S(1, b)会导致算术溢出：

Private Function F(ByVal x As UInteger) As UInteger
    Dim a As UShort
    Dim b As UShort
    Dim c As UShort
    Dim d As UShort
    Dim y As UInteger

    d = CUShort((x And &HFF))
    x >>= 8
    c = CUShort((x And &HFF))
    x >>= 8
    b = CUShort((x And &HFF))
    x >>= 8
    a = CUShort((x And &HFF))
    y = S(0, a) + S(1, b)
    y = y Xor S(2, c)
    y = y + S(3, d)

    Return y
End Function

有人可以帮我解决这个问题吗？

Answer 1

您可以禁用整数溢出检查（Advanced Compiler Settings Dialog Box (Visual Basic)）或将y声明为UInt64然后

Return CUInt(y And &HFFFFFFFF)

Answer 2

添加两个整数（Int32）的结果必须存储到Int64中，以确保结果可以存储而不会溢出。

因此，在这种情况下，您的方法应该返回UInt64，y也应该是UInt64。

算术运算导致溢出 - 河豚算法

2 个答案: