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    一次变色龙哈希函数及其在可修正区块链中的应用

    One-Time Chameleon Hash Function and Its Application in Redactable Blockchain

    • 摘要: 提出了称作一次变色龙哈希函数的新密码学原语:同一哈希值的2个原像(一次碰撞)不会暴露任何陷门信息,而同一哈希值的3个原像(二次碰撞)则会暴露部分陷门信息,但足以导致严重的安全危害.基于经典的RSA困难问题构造了简单高效的一次变色龙哈希函数方案,并在随机预言模型下证明了其安全性.应用该一次变色龙哈希函数方案,进一步高效实现了对每个区块仅允许至多一次修正的可修正区块链,而任何区块的二次修改都将导致区块链崩溃的惩罚.对区块链进行有效治理是网络空间安全治理的关键领域,而可修正区块链则构成了区块链监管和治理的最核心技术.所提出的可修正区块链方案具有高效和修正权限契合实际需求的两大特点,有望为区块链监管(尤其是链上有害数据的事后治理)提供有力的技术参考.

       

      Abstract: A new cryptographic primitive called a one-time chameleon Hash function is proposed for the first time. For this new primitive, two pre-images of the same Hash value (i.e. one collision) will not expose any trapdoor information, while three pre-images of the same Hash value (i.e. two collisions) will expose some trapdoor information, but it is enough to cause some serious security hazards. An efficient one-time chameleon Hash function scheme is constructed based on the classical RSA hard problem. Then its security is proved based on the RSA assumption in the random oracle model. By using this one-time chameleon Hash function scheme, a redactable blockchain scheme is further implemented efficiently, which only allows one redaction at most for each block, and any second redaction of the block will result in the penalty of the blockchain crash. Effective governance of blockchain is the key area of cyberspace security governance, and the redactable blockchain constitutes the most core technology of blockchain supervision and governance. The redactable blockchain scheme proposed in this paper has two characteristics of high efficiency and redacting restrictions compatible with the practical demand. So it is expected to provide a powerful technical method for blockchain supervision (especially for the post-governance of harmful data stored on the chain).

       

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