【作者】 周宇；

【导师】 胡天磊； 陈刚；

【作者基本信息】 浙江大学 ， 计算机技术， 2015， 硕士

【摘要】 随着移动终端的日益普及,终端与终端间即时通信的需求也越发迫切。即时通讯技术有在线和离线之分。然而,由于目前的网络还不够普及,所以终端间离线的即时通讯技术也起着十分重要的作用。近场通讯技术就这样应运而生。但是,由于近场通讯技术需要专用的物理硬件,造价昂贵而且不易普及,所以,本文设计了一套声波通讯系统,用于近距离离线通讯。相比于近场通讯技术,声波通讯不需要专用的物理设备,廉价且有利于普及。本文分析了目前仅有的两个非开源系统,Chirp和当面付。通过对它们的技术实现分析,发现它们在通信过程中,需要网络的配合,才能发送数据。而且,它们对于数据安全的保证,绝大部分依赖于服务器进行验证。所以,在其通信过程中,它们会很容易的受到非法用户的攻击。本文针对声波传播的特性,提出了一套完整的声波通讯编码及协议。在数据压缩方面,结合传统的行程长度编码,设计出适用于声波通讯系统的行程长度编码的改进版。该压缩算法是在声波层面上的压缩,而不是数字信号方面的压缩。在离线的情况下,针对声波数据安全和数据完整性验证这两个问题,提出了以MD5码进行混淆编码的安全和完整性验证的算法。在有网络的环境下,声波通讯系统能够提供安全信道进行通信。更多还原

【Abstract】 With the spread of mobile terminal, the instant communication between mobile terminals is growing fast. Instant communication can be divided into online and offline communication. Because lack of the internet, offline communication between mobile terminals also plays an important part of the world. The near field communication (NFC) technology is growing up. But the equipment of NFC is much expansive and inconvenient to spread. In this paper, we propose a sound wave communication system, which aims at short distance and offline communication. Comparing with NFC, sound wave communication is much cheaper.In this paper, we analyze two non-open source projects, called Chirp and Alipay. Analyzing their implementation technology, we can figure out that their communication would rely on the internet. Moreover, their security depend on the server side logic to guarantee. During their communication, they would likely to be attacked by illegal clients.In this paper, we propose a sound wave communication protocol. To deal with the data compression problem, we propose an improved version of Run Length Encoding which is used to compress the sound wave during communication. What’s more, to deal with the integrity and security problem in offline scenario, we propose a method which would mix the MD5 numbers into the original data to provide basic security policy. While in online scenario, we could provide security channel for clients to communication using our system.更多还原