# Flag Checker

The binary expects a 34-character flag.
For each character at index i, the binary performs:

```
temp = (input[i] ^ 0x5A) + i;
encoded_byte = ROTL(temp, 3);
```

The resulting array of 34 encoded bytes is compared against a constant array:
```
F8 A8 B8 21 60 73 90 83 80 C3 9B 80 AB 09 59 D3 21 D3 DB D8
FB 49 99 E0 79 3C 4C 49 2C 29 CC D4 DC 42
```

Python exploit to get flag

```
def ror(val, r_bits, max_bits=8):
return ((val >> r_bits) | (val << (max_bits - r_bits))) & ((1 << max_bits) - 1)

target = [
0xF8, 0xA8, 0xB8, 0x21, 0x60, 0x73, 0x90, 0x83, 0x80, 0xC3,
0x9B, 0x80, 0xAB, 0x09, 0x59, 0xD3, 0x21, 0xD3, 0xDB, 0xD8,
0xFB, 0x49, 0x99, 0xE0, 0x79, 0x3C, 0x4C, 0x49, 0x2C, 0x29,
0xCC, 0xD4, 0xDC, 0x42
]

flag = ""

for i, enc_byte in enumerate(target):
T = ror(enc_byte, 3)
orig = ((T - i) & 0xFF) ^ 0x5A
flag += chr(orig)

print(flag)

```

```
ENO{R3V3R53_3NG1N33R1NG_M45T3R!!!}
```