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Beyond Ring Signatures: Understanding the Role of FCMPs in Monero's Growth

Monero, known for its commitment to privacy, continues to innovate to ensure the security of its users’ transactions. Developer Luke ‘Kabaya’ Parker has introduced Full-Chain Membership Proofs (FCMPs), designed to enhance anonymity throughout the network and potentially strengthen the price of XMR.

What are FCMPs?

FCMPs are a new way to protect privacy in the Monero network. One cryptographic technology Monero has been using is Ring Signatures, which anonymize a sender’s identity. The user’s keys are integrated with other public keys to form a broad “ring” of possible senders. Ring Signatures, though, are vulnerable to attacks such as the Exchange Attack Everywhere (EAE). This attack reduces the anonymity set of the ring signature, making it easier to identify the sender, particularly if the sender reuses the same address. FCMPs offer better protection by proving that an output spent is one of any outputs on the chain. This significantly increases the anonymity set and makes it much harder for someone to trace transactions. 

There are two proposals for FCMPs: one called FCMPs and another called FCMP++s. FCMPs will be integrated with Seraphis and will add features like transaction chaining, outgoing view keys, and forward secrecy. FCMP++s add even more features like Spend Authorization and Linkability. These proposals aim to improve privacy without requiring substantial changes to the Monero protocol.

Understanding New Terms

Transaction chaining allows signing a transaction spending another one before it’s published, enabling certain types of off-chain transactions.

Outgoing view keys let you see when received Monero outputs are spent, providing more certainty and security, especially for cold wallets and multi-signature setups.

Forward secrecy means that even if someone gains access to your private information in the future, they won’t be able to use it to decrypt past communications.

Spend authorization ensures that the output being spent in a transaction is authorized by the owner of the private key.

Linkability refers to the capability of connecting different transactions or outputs on the Monero blockchain. With FCMPs, the goal is to prevent this linkability, ensuring that transactions and outputs remain unlinkable, thereby enhancing privacy. Even if someone tries to analyze the blockchain, they won’t be able to trace transactions back to specific users or addresses, preserving anonymity.

The Role of Seraphis in FCMPs

Seraphis is a software upgrade for Monero that sets the stage for improving privacy and where FCMPs will be incorporated. Seraphis introduces key elements needed for FCMPs to work effectively, such as new transaction formats and structures. Monero enhances its ability to protect user privacy and anonymize transactions on the blockchain by implementing Seraphis.

Implications and Future Developments

FCMPs have the potential to significantly enhance the privacy and security of Monero transactions. By replacing traditional ring signatures with FCMPs, Monero transactions can achieve a higher level of anonymity and resistance against attacks. This increased privacy could attract more users to Monero and further bolster its reputation as a leading privacy-focused cryptocurrency.

Impact on Monero Wallets

The introduction of FCMPs would impact XMR wallets by necessitating updates to accommodate the new protocol. Implementing these features in wallet code may be delayed to prioritize complete sender privacy. This approach allows for a focused and gradual rollout, ensuring minimal disruption and maximum security. Wallets would be able to adopt these features at their own pace without the need for additional hard forks or privacy concerns.

In the meantime, users can make a habit of taking these steps:

  1. Regularly back up wallet data, including private keys and recovery phrases, and store them securely offline.
  2. Keep wallet software updated to the latest version to ensure it incorporates the latest security patches and features.
  3. Double-check transaction details before confirming them to ensure they are accurate and legitimate.
  4. Consider using hardware wallets, which offer enhanced security by keeping private keys offline and isolated from potential online threats.
  5. Exercise caution when entering wallet information online and avoid clicking on suspicious links or providing sensitive information to unknown sources.

FCMPs represent a significant milestone in Monero’s evolution to strengthen its position as a leading privacy coin. By addressing vulnerabilities associated with traditional ring signatures and introducing innovative mechanisms, FCMPs pave the way for a more robust and resilient Monero network. Implementing FCMPs underscores Monero’s commitment to anonymity to further solidify Monero’s reputation as a reliable and privacy-preserving digital currency.