无可信PKG的基于身份的指定接收者群签密方案*

利用签密的思想,对基于身份的群签名方案进行改进,提出无可信PKG（私钥生成中心）的基于身份的指定接收者群签密方案。在提出的方案中,只有指定接收者可以从群签密密文恢复出被群签密消息的明文来验证群签密的有效性;并可以通过指定接收者进一步公开相关信息,转换为不泄露消息明文但可以被公开验证的群签名。该方案能够同时保证消息的机密性、可认证性和不可否认性。此外,群公钥的大小和群签密的长度独立于群成员的个数。

ID based designated recipient group signcryption scheme without trusted PKG

Based on the idea of signcryption, an ID based designated recipient group signcryption scheme without trusted PKG(private key generator) was proposed by improving an ID based group signature scheme. In the proposed scheme, only the designated recipient could recover the group signcrypted plain message from the ciphertext to verify the validity of the group signcryption. The proposed scheme could be converted into a group signature scheme with public verifiability by using the relevant information published by the designated recipient, which did not disclose the plain message. Moreover, the confidentiality, authenticity and non repudiation of message were guaranteed simultaneously. The size of the group public key and the length of the group signcryption were independent on the size of the group.