Abstract: This paper proposes a secure key issuing scheme based on Key Privacy Authority（KPA）and Privacy Chum（PC）, for the Distributed Online Social Networks using Identity-based Encryption（IBE）. The scheme resolves secure key issuing without secure channels. In the scheme, KPA and PC can’t imitate users in networks to gain users’ key. The results show that this scheme is efficient and strong adaptability, and can support large scale Online Social Networks.

Key words: privacy protection, identity-based encryption, key privacy authority, privacy chum, secure key issuing, distributed online social networks

摘要： 为基于身份加密（IBE）的分布式在线社会网络，提出了一种基于密钥隐私机构（KPA）和隐私密友（PC）的密钥发布方案，该方案解决了在没有安全通道情况下的安全密钥发布问题。方案中KPA和PC都不能通过效仿网络中的用户获得用户密钥。结果表明该方案高效且适应性强，并能支持大规模的在线社会网络。

关键词: 隐私保护, 基于身份加密, 密钥隐私机构, 隐私密友, 安全密钥发布, 分布式在线社会网络