What Is Censorship Resistance?

Defining Censorship Resistance

When crypto advocates explain the benefits of the blockchain, they often list a few key characteristics: decentralization, transparency, security, immutability, and censorship resistance.

In everyday discourse, conversations regarding censorship often pertain to issues around free speech, freedom of the press, and the suppression of information and expression. In the context of public blockchains like Bitcoin and Ethereum, the meaning is similar. Instead of referring to the suppression of information, censorship in this context refers to the suppression of financial activity. Censorship resistance, then, is fundamentally related to who can use the blockchain and for what purpose, as well as who can change the blockchain.

The Need for Censorship-Resistant Blockchains

In the first sense, censorship resistance describes the ability of practically anyone to use protocols such as Bitcoin and Ethereum. You don’t have to be a certain age, live in a certain location, or have a particular political affiliation to access blockchain networks like Bitcoin. With access to the internet, you can run the software, examine the code, and create your own copy of the code.

Censorship resistance is also used in a different context to describe the effects of a particular blockchain’s decentralization. Public blockchains don’t require intermediaries to verify transactions. Instead, they rely on cryptography and a peer-to-peer (P2P) network. This architecture means that no one is supposed to have the ability to prevent you from sending a transaction using a censorship-resistant blockchain. In turn, this means that you cannot be deplatformed (kicked off the blockchain network) for sending funds to people or entities that are cut off from the legacy financial system for political, economic, or other reasons.

Finally, censorship resistance can also refer to the immutability of the blockchain — the irreversibility of transactions once they are executed. This is important, because public blockchains are designed to prevent anyone from rewriting the history of the shared ledger to serve particular financial, political, or other interests. The reason such a safeguard is possible is due to the technical design of the blockchain. Miners organize transactions into blocks, and once the blocks have been added to the blockchain, they are cryptographically linked to previous blocks. As a result, if anyone sought to change one block, they would be forced to alter the entire blockchain — an incredibly cumbersome task.

It is worth noting that while this task would be cumbersome, it is not wholly impossible. In the event of a 51% attack, in which a single entity hypothetically gains control of the majority of the blockchain’s computing power, it would be possible to alter the ledger. However, blockchains like Bitcoin and Ethereum have been designed to make these attacks so prohibitively expensive and resource intensive that they are highly unlikely to occur on such censorship-resistant networks.