Saiko Labs
A decompiled routine XORs the flag with a constant. Undo it.
Decompiled validator. The flag bytes are XOR'd with key 0x2a:
char key = 0x2a;
unsigned char enc[] = { 0x59, 0x4b, 0x43, 0x41, 0x45, 0x51, 0x49, 0x58, 0x4b, 0x49, 0x41, 0x75, 0x5e, 0x42, 0x4f, 0x75, 0x42, 0x4b, 0x44, 0x4e, 0x59, 0x42, 0x4b, 0x41, 0x4f, 0x57 };
for (int i = 0; i < sizeof(enc); i++) putchar(enc[i] ^ key);