In the implicit certification model, the process of verifying the validity of the signer's public key is combined with the verification of the signature itself. When compared to traditional, explicit certificates, the main advantage of the implicit approach lies in the shorter public key validation data. This property is particularly important in resource-constrained scenarios where public key validation is performed very often, which is common in vehicular communications (V2X) that employ pseudonym certificates. In this article, we show an alternative Schnorr-based implicit certification procedure that can improve the efficiency of a popular V2X-oriented Vehicular Public Key Infrastructure (VPKI), the Security Credential Management System (SCMS). As an additional contribution, we show that SCMS's underlying certificate provisioning procedure, based on butterfly keys, is vulnerable to existential forgery attacks under certain conditions. We then discuss how this issue can be fixed in an effective and efficient manner.

中文翻译：

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基于Schnorr的隐式认证：提高车辆通信的安全性和效率

在隐式认证模型中，验证签名者公钥有效性的过程与签名本身的验证相结合。与传统的显式证书相比，隐式方法的主要优点在于较短的公钥验证数据。在经常执行公钥验证的资源受限的情况下，此属性特别重要，这在采用假名证书的车辆通信（V2X）中很常见。在本文中，我们展示了另一个基于Schnorr的隐式认证程序，该程序可以提高流行的面向V2X的车辆公共密钥基础结构（VPKI），安全凭证管理系统（SCMS）的效率。作为额外的贡献，我们表明SCMS' 基于蝶形密钥的基础证书预配过程在某些条件下容易受到存在的伪造攻击。然后，我们讨论如何有效有效地解决此问题。