Blockchain-based covert communication has opened up a new research direction for the covert communication field. In blockchain-based storage covert communication, reliability can be guaranteed because of the inherent immutable property of blockchain. Besides, enhanced undetectability is also achieved because the sender and the receiver do not need to establish a direct connection or be online simultaneously. However, in existing blockchain-based solutions, pre-negotiated and fixed addresses are used as static labels to scan the specific transaction that embeds covert messages, which increases the risk of channel exposure. Moreover, some of them do not support large covert message transmission. In this paper, we present an effective blockchain-based covert storage channel with dynamic labels. More specifically, a novel dynamic label mechanism is proposed to help the receiver extract the covert message efficiently, whereas adversaries cannot distinguish whether a block contains specific transactions. Besides, a message segmentation mechanism is also proposed to achieve large covert message transmission. Theoretical security analysis and detailed experimental evaluations based on the public Ethereum blockchain network show that the proposed scheme is secure under Chosen Hidden-text Attacks with acceptable efficiency.

基于区块链的隐蔽通信为隐蔽通信领域开辟了一个新的研究方向。在基于区块链的存储隐蔽通信中，由于区块链固有的不可篡改特性，可靠性可以得到保证。此外，还实现了增强的不可检测性，因为发送方和接收方不需要建立直接连接或同时在线。然而，在现有的基于区块链的解决方案中，预先协商和固定的地址被用作静态标签来扫描嵌入隐蔽消息的特定交易，这增加了通道暴露的风险。此外，其中一些不支持大型隐蔽消息传输。在本文中，我们提出了一种有效的基于区块链的带有动态标签的隐蔽存储通道。进一步来说，提出了一种新颖的动态标签机制来帮助接收方有效地提取隐蔽消息，而对手无法区分块是否包含特定交易。此外，还提出了一种消息分割机制来实现大的隐蔽消息传输。基于公共以太坊区块链网络的理论安全分析和详细的实验评估表明，所提出的方案在选择隐藏文本攻击下是安全的，效率可接受。