Proxy re-encryption cryptosystem enables proxy to re-encrypt the ciphertext and protects the privacy of the corresponding plaintext. Hence, this type of cryptosystem has found tremendous applications in data sharing in cloud computing, email forwarding, securing file systems, and so on. In practice, proxy re-encryption has to support verification of ciphertext to reduce the users' computational burden. The ciphertext verification can be achieved through a public, private, or delegatable manner. Delegatable verification is more generic in that it can be easily converted into the other two verification methods. However, almost all existing schemes with delegatable verifiability only achieve replayable chosen ciphertext security. Hence, in this paper we propose a more secure proxy re-encryption scheme with delegatable verifiability. Specifically, we utilize a short signature scheme to prevent an attacker from forging a valid ciphertext, and prevent an attacker from forging a signature. As a result, our scheme is secure against chosen ciphertext attacks under the standard model.

中文翻译：

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具有可委托验证的改进的代理重新加密

代理重新加密密码系统使代理可以重新加密密文，并保护相应明文的隐私。因此，这种类型的密码系统已经在云计算，电子邮件转发，文件系统安全等数据共享中获得了巨大的应用。实际上，代理重新加密必须支持密文验证，以减少用户的计算负担。密文验证可以通过公共，私有或可代理方式来实现。可委托验证更为通用，因为它可以轻松转换为其他两种验证方法。但是，几乎所有具有可代理验证的现有方案都只能实现可重播的选定密文安全性。因此，在本文中，我们提出了一种具有可代理验证性的更安全的代理重新加密方案。特别，我们利用短签名方案来防止攻击者伪造有效的密文，并防止攻击者伪造签名。结果，我们的方案在标准模型下可以安全地抵抗选择的密文攻击。