As an immutable append-only distributed ledger, blockchain allows a group of participants to reach a consensus in an untrustworthy ecosystem. Immutability is a blockchain feature that persists data forever, but it is no longer legal in reality. Blockchain has unchangeable improper contents that violate laws. Moreover, data regulation toward “the right to be forgotten” requires blockchain must be modifiable. To address this problem, redactable blockchain has been introduced to relax immutability in a controlled way. However, once a participant is authorized, she/he can rewrite any content and no penalty for the malicious behavior that hinders the wide deployment of redactable blockchain in practice. In this paper, we introduce a new notion, dubbed $k$ -time modifiable and epoch-based redactable blockchain (KERB) with a monetary penalty to control rewriting privileges and penalize malicious behaviors. Our solution is built up from simple building blocks: digital signatures and chameleon hashes. We give a formal definition and security models of KERB, and present a generic construction along with formal proofs. The extensive comparison and experimental analysis illustrate that our solution enjoys superior functionalities and performances than the state-of-the-art solutions.

中文翻译：

---

K-Time 可修改和基于 Epoch 的可编辑区块链

作为一个不可变的仅附加分布式账本，区块链允许一组参与者在一个不可信的生态系统中达成共识。不变性是一种区块链功能，可以永久保存数据，但在现实中不再合法。区块链具有不可更改的违法内容。此外，针对“被遗忘权”的数据监管要求区块链必须是可修改的。为了解决这个问题，引入了可编辑的区块链来以可控的方式放松不变性。然而，一旦参与者被授权，她/他可以重写任何内容，并且不会对阻碍可编辑区块链在实践中广泛部署的恶意行为进行惩罚。在本文中，我们引入了一个新概念，称为 $千$ -时间可修改和基于纪元的可编辑区块链（KERB），带有货币惩罚以控制重写权限并惩罚恶意行为。我们的解决方案由简单的构建块构建而成：数字签名和变色龙哈希。我们给出了 KERB 的正式定义和安全模型，并提供了一个通用构造和形式证明。广泛的比较和实验分析表明，我们的解决方案比最先进的解决方案具有更优越的功能和性能。