Overview
Ciphertext formula C[i] = P[i-1] ^ P[i] ^ P[i+1] is reversed starting from known flag prefix hwj{.
Reconnaissance
Knowing first four bytes hwj{ allows linear recurrence solve.
Exploitation Strategy
Solve sequentially: P[i+1] = C[i] ^ P[i] ^ P[i-1].
Solution Code
cipher = bytes.fromhex(open("telemetry.out").read().strip())
plain = bytearray(b"hwj{")
for i in range(3, len(cipher)-1):
plain.append(cipher[i] ^ plain[i] ^ plain[i-1])
print(plain.decode())Flag
hwj{c4sc4d1ng_x0r_1s_3l3g4nt!}