【摘要】 随着数字化技术的发展的迅猛发展和Internet的普及,网上交易和传播的电子图书、音乐、视频和软件等数字内容越来越多.由于数字化信息极易被复制、修改和传播,盗版现象日益严重,给相关权利人造成巨大的经济损失.广播加密技术解决版权保护问题并能有效地管理密钥.但用户量巨大的时候,通信量和用户端密钥存储量都急剧增加,为了解决这一问题,本文利用子集覆盖的思想,提出一个允许免费接收者的完全子树广播加密方案,当撤销用户很多的时候,显著降低了系统的通信量.虽然一部分人可能免费接收内容,这些损失可以由减少的带宽费用得到补偿.更多还原

【Abstract】 With the rapid development of digital technology and the wide use of internet,more and more e-book,music,video and softw are are distributed and consumed via netw ork. How ever,there are many pirated copy for that it’s easy to copy,edit and distribute digital documents,it bring about hug loss. Broadcast encryption can protect the intellectual property of digital contents. How ever, w hen there are a great number of user,the communication and private keys w hich must store in user side increase rapidly. To solve this problem,this paper proposed a complete sub-tree broadcast encryption scheme w ith free-riders. This scheme decrease the communication cost w hen revoked user set is large.更多还原