本帖最后由 hotpower 于 2009-12-19 08:33 编辑
现以CRC8安全密码举例(在已知CRC权值和方向时的例子)：
某客人想进入菜农的雁塔菜地，村长交给他256*256=65536把钥匙。其中256把钥匙可以进入菜地大门，
在这256把钥匙里只有一把可以打开“大棚菜地”，其他255把都是进入一些不重要的部门。
客人首先要想如何找到这256把钥匙，其次就是找那把开门之钥。
此密码的晕人之处在于它不是“基于数学难题”或“S盒的混淆和发散”，而是“基于密钥碰撞”。
即256把钥匙都可以进入菜地大门，但只有一把才可以打开“大棚菜地”。
假若各个“大棚”都加以伪装，那么客人可能被误导到其他地方。
此算法最大的好处是“透明而无陷门”，理论上是“不可**的”即只能穷举。
客人拿到65536把钥匙后，一把一把地试着开锁，255次打开大门后的惊喜随之都变为失望~~~
只有那唯一1次才能打开“大棚菜地”~~~估计此时他没有喜悦~~~只有酸痛的手~~~
本例是最简单的CRC8安全密码，若CRC4096不知该复杂到什么地步。
最新版本的HotWC3_V508b以开始支持对CRC初值出值碰撞的逆向。
摘录HotWC3_V508b攻击后自动提供的数据表：
初值和出值发生CRC密钥碰撞：
CRC多项式：左移CRC8=X8+X2+X+1
CRC简 写：CRCL8_07_AD_00
CRC初值出值碰撞对：
碰撞初值：0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F;
碰撞出值：0x4A,0x4D,0x44,0x43,0x56,0x51,0x58,0x5F,0x72,0x75,0x7C,0x7B,0x6E,0x69,0x60,0x67;
碰撞初值：0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F;
碰撞出值：0x3A,0x3D,0x34,0x33,0x26,0x21,0x28,0x2F,0x02,0x05,0x0C,0x0B,0x1E,0x19,0x10,0x17;
碰撞初值：0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28,0x29,0x2A,0x2B,0x2C,0x2D,0x2E,0x2F;
碰撞出值：0xAA,0xAD,0xA4,0xA3,0xB6,0xB1,0xB8,0xBF,0x92,0x95,0x9C,0x9B,0x8E,0x89,0x80,0x87;
碰撞初值：0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x3A,0x3B,0x3C,0x3D,0x3E,0x3F;
碰撞出值：0xDA,0xDD,0xD4,0xD3,0xC6,0xC1,0xC8,0xCF,0xE2,0xE5,0xEC,0xEB,0xFE,0xF9,0xF0,0xF7;
碰撞初值：0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F;
碰撞出值：0x8D,0x8A,0x83,0x84,0x91,0x96,0x9F,0x98,0xB5,0xB2,0xBB,0xBC,0xA9,0xAE,0xA7,0xA0;
碰撞初值：0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x5B,0x5C,0x5D,0x5E,0x5F;
碰撞出值：0xFD,0xFA,0xF3,0xF4,0xE1,0xE6,0xEF,0xE8,0xC5,0xC2,0xCB,0xCC,0xD9,0xDE,0xD7,0xD0;
碰撞初值：0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F;
碰撞出值：0x6D,0x6A,0x63,0x64,0x71,0x76,0x7F,0x78,0x55,0x52,0x5B,0x5C,0x49,0x4E,0x47,0x40;
碰撞初值：0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x7B,0x7C,0x7D,0x7E,0x7F;
碰撞出值：0x1D,0x1A,0x13,0x14,0x01,0x06,0x0F,0x08,0x25,0x22,0x2B,0x2C,0x39,0x3E,0x37,0x30;
碰撞初值：0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,0x88,0x89,0x8A,0x8B,0x8C,0x8D,0x8E,0x8F;
碰撞出值：0xC3,0xC4,0xCD,0xCA,0xDF,0xD8,0xD1,0xD6,0xFB,0xFC,0xF5,0xF2,0xE7,0xE0,0xE9,0xEE;
碰撞初值：0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0x9B,0x9C,0x9D,0x9E,0x9F;
碰撞出值：0xB3,0xB4,0xBD,0xBA,0xAF,0xA8,0xA1,0xA6,0x8B,0x8C,0x85,0x82,0x97,0x90,0x99,0x9E;
碰撞初值：0xA0,0xA1,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7,0xA8,0xA9,0xAA,0xAB,0xAC,0xAD,0xAE,0xAF;
碰撞出值：0x23,0x24,0x2D,0x2A,0x3F,0x38,0x31,0x36,0x1B,0x1C,0x15,0x12,0x07,0x00,0x09,0x0E;
碰撞初值：0xB0,0xB1,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xBB,0xBC,0xBD,0xBE,0xBF;
碰撞出值：0x53,0x54,0x5D,0x5A,0x4F,0x48,0x41,0x46,0x6B,0x6C,0x65,0x62,0x77,0x70,0x79,0x7E;
碰撞初值：0xC0,0xC1,0xC2,0xC3,0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xCB,0xCC,0xCD,0xCE,0xCF;
碰撞出值：0x04,0x03,0x0A,0x0D,0x18,0x1F,0x16,0x11,0x3C,0x3B,0x32,0x35,0x20,0x27,0x2E,0x29;
碰撞初值：0xD0,0xD1,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,0xDB,0xDC,0xDD,0xDE,0xDF;
碰撞出值：0x74,0x73,0x7A,0x7D,0x68,0x6F,0x66,0x61,0x4C,0x4B,0x42,0x45,0x50,0x57,0x5E,0x59;
碰撞初值：0xE0,0xE1,0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xEB,0xEC,0xED,0xEE,0xEF;
碰撞出值：0xE4,0xE3,0xEA,0xED,0xF8,0xFF,0xF6,0xF1,0xDC,0xDB,0xD2,0xD5,0xC0,0xC7,0xCE,0xC9;
碰撞初值：0xF0,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFC,0xFD,0xFE,0xFF;
碰撞出值：0x94,0x93,0x9A,0x9D,0x88,0x8F,0x86,0x81,0xAC,0xAB,0xA2,0xA5,0xB0,0xB7,0xBE,0xB9;
菜农HotPower@126.com 2009.12.18 于雁塔菜地
HotPower星期冗余三角HotWC3密码网上在线运算器(V5.08a)
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