An efficient quantum multi-proxy signature scheme was proposed recently, in which the original signatory Alice distributed her authority to several proxy signatories, and then each proxy signatory can sign the message for her alone. In this work, we give a cryptanalysis on this scheme and then point out an unnoticed problem that the proxy signatory must send the signed message to the verifier when he signs it, which is in conflict with the requirement of digital signatures. Furthermore, this problem will give a good chance for an unreliable proxy signatory to deny his signature on the message. Finally, an improved version is presented, which is more economical and practical with current technology compared with the original scheme.

中文翻译：

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有效的量子多代理签名分析

最近提出了一种有效的量子多代理签名方案，在该方案中，原始签名者爱丽丝将其权限分配给多个代理签名者，然后每个代理签名者都可以单独为她签名消息。在这项工作中，我们对该方案进行了密码分析，然后指出了一个未被注意的问题，即代理签名人在签名者签名时必须将签名的消息发送给验证者，这与数字签名的要求相冲突。此外，此问题将为不可靠的代理签名者拒绝在消息上签名提供了很好的机会。最后，提出了一种改进的版本，与原始方案相比，使用当前技术更经济，更实用。