typedef unsigned int UInt32;
typedef unsigned char UInt8;
class Crc32 {
public:
Crc32();
void append(const void* buffer, UInt32 size);
void set(UInt32 crc);
UInt32 get() const;
const UInt8* findReverse(UInt32 desiredCrc) const;
private:
static UInt32 crc32Table[256];
static int reverseCrc32Table[256];
static UInt8 patchBytes[4];
UInt32 crc_;
};
UInt32 Crc32::crc32Table[256] = {
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};
int Crc32::reverseCrc32Table[256] = {
0x00, 0x41, 0xc3, 0x82, 0x86, 0xc7, 0x45, 0x04,
0x4d, 0x0c, 0x8e, 0xcf, 0xcb, 0x8a, 0x08, 0x49,
0x9a, 0xdb, 0x59, 0x18, 0x1c, 0x5d, 0xdf, 0x9e,
0xd7, 0x96, 0x14, 0x55, 0x51, 0x10, 0x92, 0xd3,
0x75, 0x34, 0xb6, 0xf7, 0xf3, 0xb2, 0x30, 0x71,
0x38, 0x79, 0xfb, 0xba, 0xbe, 0xff, 0x7d, 0x3c,
0xef, 0xae, 0x2c, 0x6d, 0x69, 0x28, 0xaa, 0xeb,
0xa2, 0xe3, 0x61, 0x20, 0x24, 0x65, 0xe7, 0xa6,
0xea, 0xab, 0x29, 0x68, 0x6c, 0x2d, 0xaf, 0xee,
0xa7, 0xe6, 0x64, 0x25, 0x21, 0x60, 0xe2, 0xa3,
0x70, 0x31, 0xb3, 0xf2, 0xf6, 0xb7, 0x35, 0x74,
0x3d, 0x7c, 0xfe, 0xbf, 0xbb, 0xfa, 0x78, 0x39,
0x9f, 0xde, 0x5c, 0x1d, 0x19, 0x58, 0xda, 0x9b,
0xd2, 0x93, 0x11, 0x50, 0x54, 0x15, 0x97, 0xd6,
0x05, 0x44, 0xc6, 0x87, 0x83, 0xc2, 0x40, 0x01,
0x48, 0x09, 0x8b, 0xca, 0xce, 0x8f, 0x0d, 0x4c,
0x95, 0xd4, 0x56, 0x17, 0x13, 0x52, 0xd0, 0x91,
0xd8, 0x99, 0x1b, 0x5a, 0x5e, 0x1f, 0x9d, 0xdc,
0x0f, 0x4e, 0xcc, 0x8d, 0x89, 0xc8, 0x4a, 0x0b,
0x42, 0x03, 0x81, 0xc0, 0xc4, 0x85, 0x07, 0x46,
0xe0, 0xa1, 0x23, 0x62, 0x66, 0x27, 0xa5, 0xe4,
0xad, 0xec, 0x6e, 0x2f, 0x2b, 0x6a, 0xe8, 0xa9,
0x7a, 0x3b, 0xb9, 0xf8, 0xfc, 0xbd, 0x3f, 0x7e,
0x37, 0x76, 0xf4, 0xb5, 0xb1, 0xf0, 0x72, 0x33,
0x7f, 0x3e, 0xbc, 0xfd, 0xf9, 0xb8, 0x3a, 0x7b,
0x32, 0x73, 0xf1, 0xb0, 0xb4, 0xf5, 0x77, 0x36,
0xe5, 0xa4, 0x26, 0x67, 0x63, 0x22, 0xa0, 0xe1,
0xa8, 0xe9, 0x6b, 0x2a, 0x2e, 0x6f, 0xed, 0xac,
0x0a, 0x4b, 0xc9, 0x88, 0x8c, 0xcd, 0x4f, 0x0e,
0x47, 0x06, 0x84, 0xc5, 0xc1, 0x80, 0x02, 0x43,
0x90, 0xd1, 0x53, 0x12, 0x16, 0x57, 0xd5, 0x94,
0xdd, 0x9c, 0x1e, 0x5f, 0x5b, 0x1a, 0x98, 0xd9
};
UInt8 Crc32::patchBytes[4] = { 0 };
Crc32::Crc32() : crc_(~0U) {}
void Crc32::set(UInt32 crc) {
crc_ = crc;
}
UInt32 Crc32::get() const {
return ~crc_;
}
void Crc32::append(const void* buffer, UInt32 size) {
const UInt8* ptr = (const UInt8*)buffer;
while (size--) {
crc_ = (crc_ >> 8) ^ crc32Table[*ptr++ ^ (crc_ & 0xff)];
}
}
const UInt8* Crc32::findReverse(UInt32 desiredCrc) const {
int crcIdx[4];
UInt32 iterCrc = ~desiredCrc;
for (int j = 3; j >= 0; j--) {
crcIdx[j] = reverseCrc32Table[iterCrc >> 24];
iterCrc = (iterCrc ^ crc32Table[crcIdx[j]]) << 8;
}
UInt32 crc = crc_;
for (int j = 0; j < 4; j++) {
patchBytes[j] = (crc ^ crcIdx[j]) & 0xff;
crc = (crc >> 8) ^ crc32Table[patchBytes[j] ^ (crc & 0xff)];
}
return patchBytes;
}
int main() {
const char* testString = "AAAAAAAAAAAAA"; //41 41 41 41 41 41 41 41 41 41 41 41 41 69 7c 5f 2d
const UInt32 targetCrc = 0x9dc0a0ea;
const int strLength = strlen(testString);
// 计算原始字符串的CRC32
Crc32 crc;
crc.append(testString, strLength);
UInt32 originalCrc = crc.get();
printf("原始字符串 CRC32: 0x%08x\n", originalCrc);
// 查找补丁字节
const UInt8* patch = crc.findReverse(targetCrc);
// 验证补丁效果
Crc32 verifier;
verifier.append(testString, strLength);
verifier.append(patch, 4);
UInt32 finalCrc = verifier.get();
// 输出结果
printf("目标 CRC32: 0x%08x\n", targetCrc);
printf("补丁字节: { 0x%02x, 0x%02x, 0x%02x, 0x%02x }\n",
patch[0], patch[1], patch[2], patch[3]);
printf("最终 CRC32: 0x%08x (%s)\n",
finalCrc, (finalCrc == targetCrc) ? "成功" : "失败");
return 0;
}
