基于广播加密的对称叛逆者追踪方案分析

The Analysis of Symmetric Traitor Tracing Scheme Based on Broadcast Encryption

对基于广播加密的对称叛逆者追踪方案进行了讨论与分析。结果表明:当用户数n不是太大时,对称方案具有高效、简单、安全性高的特性。在对称叛逆者追踪方案中,数字信息的解密密钥并非由用户单方面所知,而是由用户和数据发行商双方所共知。因此,数据发行商完全可以恶意使用此私有密钥,来诬陷诚实的授权用户。所以对称叛逆者方案不具备防诬陷性。针对对称方案的缺陷,研究出非对称方案。在非对称方案中,授权用户的解密密钥仅其本人知道,数据供应商一无所知,从而弥补了对称方案的可否认、可诬陷性。通过对4种具有代表性的对称叛逆者追踪方案的分析,在安全性的基础上,对其进行改进,可进一步研究出具有更多特性的叛逆者追踪方案。

This paper discusses the symmetric traitor tracing scheme based on broadcast encryption. The results show that the symmetric scheme is efficient, simple and secure when the number of users is not very large. But in the symmetric scheme, data supplier generates the decryption key of the digital information and distributes it to every user. Therefore data supplier can frame the honest user. That is to say the symmetric scheme has not feature to prevent the frame behavior of the data supplier. There are some asymmetric schemes which make up the defects in the symmetric scheme, because data supplier doesn＇t know the users encryption key in asymmetric scheme. Based on analysis of four symmetric traitor tracing schemes, especially their security, some schemes with more characteristics will be proposed.