rsay

rev_kids20

Task: stripped x86-64 ELF (OLLVM control-flow flattening + Heaven's Gate anti-debug) performs textbook RSA (e=65537, hardcoded balanced 2048-bit n) and prints c=m^e mod n with an unfactorable modulus. Solution: instead of factoring, recover the plaintext m before encryption — a 192-byte .rodata blob is XTEA-decrypted (key cafebabe/deadbeef/faceface/c0deefef, delta 0x9E3779B9, 42 rounds) into 96 decimal digits which, read in reverse order, form m; pow(m,65537,n)==c and m.to_bytes() is the flag.