Jabber Part 2

RingZer0 CTF

Task: a riddle letter contains one 37-byte hex payload (encrypted flag) with no crib file; the 'new direction' clue signals the Part 1 bit-level RC8 LFSR became a byte-wise GF(2^8) LFSR. Solution: use the FLAG- prefix as a crib, recover the feedback polynomial 0x47 from two overflow transitions, reconstruct the full keystream and XOR-decrypt.