A double agent has delivered an encrypted hex string. Intelligence reports suggest it was encrypted using the XOR (exclusive OR) cipher with a single repeating byte as the key. XOR encryption is symmetric—the same key both encrypts and decrypts. Your mission: brute force the key space (0-255) to reveal the secret.
4b 65 79 20 3d 20 30 31 3a 20 52 64 62 73 64 75 4a 64 78 0a 4b 65 79 20 3d 20 30 32 3a 20 51 67 61 70 67 76 49 67 7b 0a 4b 65 79 20 3d 20 30 33 3a 20 50 66 60 71 66 77 48 66 7a 0a 4b 65