Shielded Labs Engages Nicolás Della Penna for Crosslink Design Review

General
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As Crosslink approaches the end of the prototype phase, Shielded Labs is beginning a structured hardening process to evaluate the protocol’s security and overall readiness for version 1.0. With the testnet prototype nearly complete, the focus is shifting toward detailed review, stress-testing assumptions, and addressing questions and concerns raised by the community. This stage involves uncovering potential security flaws, assessing acceptable tradeoffs, and reducing unknown unknowns before the design is finalized. The goal is to increase confidence that Crosslink has no fatal flaws and is prepared for deployment if it has the support of the community and coinholders.

To support this process, we are bringing on Nicolás “Nikete” Della Penna to conduct an independent review of Crosslink’s design. Nicolás is a mechanism designer and researcher whose work spans economics, machine learning, and decentralized systems. He holds a PhD in Computer Science from the Australian National University and has published research [1] on automated market makers, prediction markets, MEV, Sybil-resistance, and the dynamics of permissionless systems. His work has appeared in venues such as NIPS, CHI, and Science, and his recent contributions include MEV-minimizing AMM design, welfare analysis of CFMMs, and unified frameworks for Sybil-resistant mechanisms. Outside academia, he is the CEO of GroupLang and has consulted for both early-stage and publicly traded companies on mechanism design and collective-intelligence systems.

Nicolás’s review will focus on evaluating the incentive structure of Crosslink, including how miners, finalizers, stakers, and the broader community are expected to behave under the current design. The audit will identify likely equilibria, potential failure modes, and the Penalty for Failure to Defend across safety, liveness, and censorship resistance. It will also examine areas where the protocol relies on incentives versus social coordination and provide concrete recommendations for how to strengthen the design. The deliverables include a written audit report, an executive summary, a slide deck, and a draft public summary to support community understanding and discussion of the findings.

Finally, we have pre-registered the scope of this review, which means publishing the specific questions, assumptions, and areas of focus before the review begins to ensure transparency about what is being evaluated and how. Anyone can review the pre-registered scope here: Mechanism Design Audit of Crosslink Zebra - 2025-12-11 - The Zebra Crosslink Book.

We see this review process as something that should become a standard part of how proposed features for future network upgrades are evaluated.

[1] Selected publications related to crypto:

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As a follow-up to our earlier announcement, Nicolás “Nikete” Della Penna has completed the first independent security and mechanism-design review of Shielded Labs’ implementation of Crosslink.

Independent security reviews are an important part of building high-security software, and this review marks the start of a broader hardening process as Crosslink transitions out of the prototype phase. The goal is not to declare the design “finished,” but to stress-test assumptions, validate core properties, and iteratively improve the design.

The review confirms that the current Crosslink design successfully introduces finality and that finality behaves as intended. This is an important validation and increases confidence in the core architecture. The review also identifies a number of critiques, proposed attacks, and potential improvements. We are actively using these results to refine and harden the design.

Not every recommendation will necessarily be adopted. Some ideas may be better suited for later iterations, including post-mainnet improvements, and in other cases we may pursue alternative solutions to the issues raised. As with any protocol design, we are carefully weighing trade offs between time-to-market, complexity, and security, rather than trying to build a protocol that is perfect in every way.

This review marks an important milestone in the development process. Before activation, we expect to carry out further security-focused analyses and independent reviews to evaluate Crosslink’s safety, production readiness, and its implications for user privacy. As the design evolves, we plan to re-engage Nikete and also seek additional independent assessments from established security audit firms.

We’re sharing the report publicly to support transparency and encourage open discussion. Over the coming week, we also plan to announce a community discussion to walk through the findings, the trade offs they raise, and how we’re thinking about next steps.

We see this kind of structured, independent review as a model for how significant protocol changes should be evaluated going forward, and we hope it becomes common practice across the ecosystem.

You can read Nikete’s full report here: https://www.nikete.com/crosslink_zebra_audit.pdf

He has also published formal proofs: https://www.nikete.com/crosslink_zebra_audit_proofs.pdf

Nikete also posted an X thread summarizing his findings here:

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Shielded Labs: Crosslink Deployment Updates
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Good to see this published and the commitment to independent review before activation.

The core asymmetry is worth sitting with. Safety is structural, liveness is economic. The system cannot be tricked into finalizing the wrong thing, but it can be made rational for everyone to stop finalizing.

R4 is not tunable. The Zombie Set does not require an attacker. The fork choice dichotomy has no 3rd option. Useful to have these tradeoffs surfaced now.

Looking forward to the walkthrough.