65 lines
2.2 KiB
C#
65 lines
2.2 KiB
C#
|
using NUnit.Framework;
|
|||
|
|
using System;
|
|||
|
|
using System.Collections.Generic;
|
|||
|
|
|
|||
|
|
namespace Obfuz.EncryptionVM.Instructions
|
|||
|
|
{
|
|||
|
|
public class MultipleInstruction : EncryptionInstructionBase
|
|||
|
|
{
|
|||
|
|
private readonly int _multiValue;
|
|||
|
|
private readonly int _revertMultiValue;
|
|||
|
|
private readonly int _opKeyIndex;
|
|||
|
|
|
|||
|
|
public MultipleInstruction(int addValue, int opKeyIndex)
|
|||
|
|
{
|
|||
|
|
_multiValue = addValue;
|
|||
|
|
_opKeyIndex = opKeyIndex;
|
|||
|
|
_revertMultiValue = (int)ModInverseOdd((uint)addValue);
|
|||
|
|
Verify();
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private void Verify()
|
|||
|
|
{
|
|||
|
|
int a = 1122334;
|
|||
|
|
Assert.AreEqual(a, a * _multiValue * _revertMultiValue);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public static uint ModInverseOdd(uint a)
|
|||
|
|
{
|
|||
|
|
if (a % 2 == 0)
|
|||
|
|
throw new ArgumentException("Input must be an odd number.", nameof(a));
|
|||
|
|
|
|||
|
|
uint x = 1; // 初始解：x₀ = 1 (mod 2)
|
|||
|
|
for (int i = 0; i < 5; i++) // 迭代5次（2^1 → 2^32）
|
|||
|
|
{
|
|||
|
|
int shift = 2 << i; // 当前模数为 2^(2^(i+1))
|
|||
|
|
ulong mod = 1UL << shift; // 使用 ulong 避免溢出
|
|||
|
|
ulong ax = (ulong)a * x; // 计算 a*x（64位避免截断）
|
|||
|
|
ulong term = (2 - ax) % mod;
|
|||
|
|
x = (uint)((x * term) % mod); // 更新 x，结果截断为 uint
|
|||
|
|
}
|
|||
|
|
return x; // 最终解为 x₅ mod 2^32
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public override int Encrypt(int value, int[] secretKey, int salt)
|
|||
|
|
{
|
|||
|
|
return value * _multiValue + secretKey[_opKeyIndex] + salt;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public override int Decrypt(int value, int[] secretKey, int salt)
|
|||
|
|
{
|
|||
|
|
return (value - secretKey[_opKeyIndex] - salt) * _revertMultiValue;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public override void GenerateEncryptCode(List<string> lines, string indent)
|
|||
|
|
{
|
|||
|
|
lines.Add(indent + $"value = value * {_multiValue} + _secretKey[{_opKeyIndex}] + salt;");
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public override void GenerateDecryptCode(List<string> lines, string indent)
|
|||
|
|
{
|
|||
|
|
lines.Add(indent + $"value = (value - _secretKey[{_opKeyIndex}] - salt) * {_revertMultiValue};");
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
}
|