recurse (RE3_recurse)

rev_kids20

Task: 64-bit PIE ELF keygen that reads a 29-byte key and validates it with a recursive checker dispatching one of four byte-predicate functions per position against a .rodata constant. Solution: reverse the four predicates and invert each one against its constant byte (brute 0..255) following the fixed function-pointer order to recover the unique key/flag.