通信工程文献翻译——摘要：我们呈现的第一个有效的基于身份加密（IBE）方案在没有随机预言时是完全安全的。我们首先呈现我们的IBE的构建和在Decisional Bilinear Diffie-Hellman问题下减小我们方案的安全性。除此之外，我们的方案能被用来构建一个在没有随机预言时在Computational Diffie-Hellman问题下安全的新的签名方案。

1、介绍

基于身份的公钥加密技术允许一个团体使用接受者的身份作为公钥加密信息。使用身份作为公钥的能力避免了分配公钥证书的需要。这是非常有用的在诸如电子邮件的应用中，在那里，这个接受者经常是离线的并且不能呈现这个公钥证书当发送者加密一个信息时。

第一个有效并且安全的基于身份加密方式被提出通过Boneh和Franklin。他们提出了一个使用有效的可计算双线性对解决方案，它在随机预言机模型下是安全的。自从那以后，提出很多在没有随机预言机模型下安全的方案。而在弱的安全模型下称为Selective-ID模型。最近，Boneh和Boyen提出了一个在没有随机预言机模型下被证明完全安全的方案。如此方案的可能性是提出了一个开放问题，然而，他们的方案效率太低以至于不能实际应用。

我们提出的第一个有效的基于身份加密在没有随机预言时是完全安全的。我们的方案被证明使用了一个Boneh和Boyen第一次使用的代数方法。

我们另外提出，我们的IBE方案表示出一个在没有随机预言的可计算D-H假设下安全的数字签名方案。早先可行的数字签名方案在依靠Strong-RSA假设和Strong-BDH假设的标准模型下是安全的。

1.1相关工作

Shamir第一次提出基于身份加密的概念作为一个挑战给研究机构，然而Boneh和Franklin第一次提出的安全并且有效的方案没有出现直到后来。为了得到他们结果这个作者采用了一个有效的可计算双线性对的新奇方法。

Canetti et.al提出了一个基于身份加密更弱的安全模型，他们称之为Slective-ID模型。在Slective-ID模型下，敌手必须首先指出他希望被挑战的的身份在全局变量产生之前。这个作者提出了一个方案，那个方案被证明是安全的在没有随机预言的Slective-ID模型......

Abstract. We present the first efficient Identity-Based Encryption (IBE) scheme that is fully secure without random oracles. We first present our IBE construction and reduce the security of our scheme to the decisional Bilinear Diffie-Hellman (BDH) problem. Additionally, we show that our techniques can be used to build a new signature scheme that is secure under the computational Diffie-Hellman assumption without random or-acles.

1 Introduction

Identity-Based Encryption allows for a party to encrypt a message using the recipient’s identity as a public key. The ability to use identities as public keys avoids the need to distribute public key certificates. This can be very useful in applications such as email where the recipient is often off-line and unable to present a public-key certificate while the sender encrypts a message.

The first efficient and secure method for Identity-Based Encryption was put forth by Boneh and Franklin [4]. They proposed a solution using efficiently computable bilinear maps that was shown to be secure in the random oracle model.

Since then, there have been schemes shown to be secure without random oracles,but in a weaker model of security know as the Selective-ID model [9, 1]. Most recently, Boneh and Boyen [2] described a scheme that was proved to be fully secure without random oracles; the possibility of such a scheme was to that point an open problem. However, their scheme is too inefficient to be of practical use.

We present the first efficient Identity-Based Encryption scheme that is fully secure without random oracles. The proof of our scheme makes use of an algebraic method first used by Boneh and Boyen [1] and the security of our scheme reduces to the decisional Bilinear Diffie-Hellman (BDH) assumption.

We additionally show that our IBE scheme implies a secure signature scheme under the computational Diffie-Hellman assumption without random oracles.Previous practical signature schemes that were secure in the standard model relied on the Strong-RSA assumption [12, 11] or the Strong-BDH assumption [3].

1.1 Related Work

Shamir [16] first presented the idea of Identity-Based Encryption as a challenge......