IDA查看源代码

src长度32，encrypt函数加密，工4个参数，_FFFC双击，可以看到是个长度为7的固定值FnTest!

加密函数将4个参数又重新命名，混淆视听，但是还是可以看到是嵌套循环，动态调试直接看结果可以发现，函数将32个字符分成7个一组，每组分别异或这个7长度的字符串 。根据异或的性质

enc = [0x20, 0x0c, 0x30, 0x57, 0x43, 0x47, 0x14, 0x77, 0x0c, 0x66, 0x54, 0x17, 0x43, 0x19, 0x71, 0x59,0x67, 0x53, 0x17, 0x45, 0x18, 0x77, 0x5c, 0x36, 0x5d, 0x45, 0x42, 0x45, 0x22, 0x08, 0x35, 0x57
]
s = "FnTest!"decrypted = ''.join(chr(enc[i] ^ ord(s[i % 7])) for i in range(len(enc)))
print(decrypted)

flag: fbd20351b21d787736d1912b866ddfa2