A Moderation Framework for the Swift and Transparent Removal of Illicit Blockchain Content

Abstract

Blockchains gained tremendous attention for their capability to provide immutable and decentralized event ledgers that can facilitate interactions between mutually distrusting parties. However, precisely this immutability and the openness of permissionless blockchains raised concerns about the consequences of illicit content being irreversibly stored on them. Related work coined the notion of redactable blockchains, which allow for removing illicit content from their history without affecting the blockchain’s integrity. While honest users can safely prune identified content, current approaches either create trust issues by empowering fixed third parties to rewrite history, cannot react quickly to reported content due to using lengthy public votings, or create large per-redaction overheads.

In this paper, we instead propose to outsource redactions to small and periodically exchanged juries, whose members can only jointly redact transactions using chameleon hash functions and threshold cryptography. Multiple juries are active at the same time to swiftly redact reported content. They oversee their activities via a global redaction log, which provides transparency and allows for appealing and reversing a rogue jury’s decisions. Hence, our approach establishes a framework for the swift and transparent moderation of blockchain content. Our evaluation shows that our moderation scheme can be realized with feasible per-block and per-redaction overheads, i.e., the redaction capabilities do not impede the blockchain’s normal operation.

Publication
Proceedings of the 2022 IEEE International Conference on Blockchain and Cryptocurrency
BibTeX Citation
@inproceedings{2022-icbc-matzutt-redactchain,
    author = {Matzutt, Roman and Ahlrichs, Vincent and Pennekamp, Jan and Karwacik, Roman and Wehrle, Klaus},
    title = {{A Moderation Framework for the Swift and Transparent Removal of Illicit Blockchain Content}},
    year = {2022},
    pages = {},
    keywords = {redactable blockchain,illicit content,chameleon hash functions,threshold cryptography},
    publisher = {IEEE},
    booktitle = {Proceedings of the 2022 IEEE International Conference on Blockchain and Cryptocurrency (ICBC '22)},
    ISBN = {},
    DOI = {},
    state = {accepted},
}