# 3. Invert the per‑byte transform to get the actual serial serial_bytes = bytes(invert_transform(b) for b in transformed) serial = serial_bytes.decode('latin-1') # keep raw bytes, printable check later print("[+] Serial candidate:", serial)

int main(int argc, char **argv) char input[64]; puts("Enter your serial: "); gets_s(input, sizeof(input)); if (check_serial(input) == 0) puts("Invalid serial! Try again."); return 1; puts("Correct! Welcome, Adeko."); return 0;

t(i) = ROL8( c_i XOR 0x5A, 3 ) ROL8 rotates an 8‑bit value left by 3 bits.

# ------------------------------------------------------------ # 1. CRC‑32 parameters (same as the binary) POLY = 0xEDB88320 INIT = 0xFFFFFFFF XOROUT = 0x00000000

Find an input string s (9 bytes) such that CRC32( b_0 … b_8 ) == 0x56C9A4F2 . 4.2. CRC‑32 is linear over GF(2) CRC‑32 with a fixed polynomial is a linear operation:

TABLE = crc32_table()

# ------------------------------------------------------------ if __name__ == "__main__": TARGET = 0x56C9A4F2

The program uses the insecure gets_s but limits to 63 characters – no overflow. The real work is in check_serial . 3.3. The serial‑checking routine In Ghidra the function is named check_serial (address 0x140001560 ). Its decompiled pseudo‑code (after some renaming) looks like this:

# ------------------------------------------------------------ # 2. Reverse the custom transform def invert_transform(b): """Given transformed byte b = ROL8(c ^ 0x5A, 3), recover original c.""" # Inverse of ROL8 by 3 is ROR8 by 3 r = ((b >> 3) | (b << 5)) & 0xFF c = r ^ 0x5A return c

(A classic “crack‑me” style reverse‑engineering challenge) 1. Overview | Item | Description | |------|-------------| | Challenge name | Adeko 9 Crack 56 | | Category | Reverse Engineering / Binary Cracking | | Platform | Windows 10 (x86‑64) – compiled with Visual Studio 2019 | | File size | ≈ 82 KB (PE32+ executable) | | Protection | No packer, but includes basic anti‑debug tricks and a custom serial‑check routine | | Goal | Produce a valid serial key that makes the program display “Correct!” (or the equivalent success message). | 2. Setup # Create a clean analysis environment mkdir adeko9-crack56 && cd adeko9-crack56 cp /path/to/Adeko9Crack56.exe . Tools used