We introduce an encryption device based on wave-chaos to enhance the physical security of wireless wave transmission. The proposed encryption device is composed of a compact quasi-2D disordered cavity, where transmit signals pass through to be distorted in time before transmission. On the receiving end, the signals can only be decrypted when they pass through an identical cavity. In the absence of a proper decryption device, the signals cannot be properly decrypted. If a cavity with a different shape is used on the receiving end, vastly different wave dynamics will prevent the signals from being decrypted, causing them to appear as noise. We experimentally demonstrate the proposed concept in an apparatus representing a wireless link.