Broadcast encryption with personalized messages (BEPM) is a newly proposed cryptographic primitive, which supports a broadcaster to deliver the common encrypted broadcast message to a group of authorized users. It also supports a broadcaster to deliver the personalized messages to the individual authorized users simultaneously. However, none of the existing BEPM schemes consider the anonymity of authorized users, which is a crucial security requirement for many BEPM application scenarios. Besides, the previous studies on BEPM only achieve security against chosen-plaintext attack adversaries. Certificate-based cryptosystem gives a viable way to construct more secure and efficient BEPM schemes. We propose the new concept of anonymous certificate-based broadcast encryption with personalized messages (ANON-CBBE-PM). Subsequently, we illustrate the formal definition and the security model of ANON-CBBE-PM. Furthermore, we present an ANON-CBBE-PM scheme, which solves key escrow problem in identity-based cryptosystem and certificate management problem in traditional public key cryptosystem. Compared with the existing BEPM schemes, the proposed scheme not only protects the privacy of authorized users, but also has advantage in performance. To be more specific, the lengths of the user secret key and the system public parameters, as well as the cost for decryption are constant. For those BEPM applications with a multitude of users whose computing ability is limited, the proposed scheme is more practical. In addition, our scheme simultaneously achieves anonymity and confidentiality under adaptive chosen-ciphertext attack in the standard model.

中文翻译：

---

具有个性化消息的基于匿名证书的广播加密


个性化消息广播加密（BEPM）是一种新提出的密码原语，它支持广播者向一组授权用户传递公共加密广播消息。它还支持广播公司同时向各个授权用户传送个性化消息。然而，现有的BEPM方案都没有考虑授权用户的匿名性，而这对于许多BEPM应用场景来说是至关重要的安全要求。此外，之前关于BEPM的研究仅实现了针对选择明文攻击对手的安全性。基于证书的密码系统提供了构建更安全、更高效的 BEPM 方案的可行方法。我们提出了基于匿名证书的广播加密和个性化消息的新概念（ANON-CBBE-PM）。随后，我们阐述了ANON-CBBE-PM的形式化定义和安全模型。此外，我们提出了一种ANON-CBBE-PM方案，它解决了基于身份的密码系统中的密钥托管问题和传统公钥密码系统中的证书管理问题。与现有的BEPM方案相比，该方案不仅保护了授权用户的隐私，而且在性能上也具有优势。具体来说，用户密钥和系统公开参数的长度以及解密的成本是恒定的。对于那些具有大量用户且计算能力有限的BEPM应用，所提出的方案更加实用。此外，我们的方案在标准模型中同时实现了自适应选择密文攻击下的匿名性和机密性。