Author: BlockWeeks
In June 2026, several dramatic events concerning privacy unfolded in the crypto world.
Zcash experienced a dramatic vulnerability crisis. A security researcher, using AI-assisted code review, discovered a hidden vulnerability in the zero-knowledge proof circuit of the Orchard protocol—potentially allowing attackers to mint unlimited fake ZEC undetected. The Zcash development team patched the issue via an emergency hard fork on June 3, but the privacy features of Orchard make it “cryptographically impossible to confirm whether the vulnerability was ever exploited.” ZEC’s price dropped as much as 55% before rebounding approximately 45% amid expectations of the Ironwood upgrade.
Almost simultaneously, the rehearing date for Tornado Cash developer Roman Storm has been set—for this fall, he will again face charges of conspiracy to launder money and conspiracy to evade sanctions. Since being sanctioned by OFAC in 2022, the story of Tornado Cash has become a landmark case in the conflict between privacy code and regulation.
On another front, StarkWare and Sui have launched compliant confidential asset transfer systems; Circle has released Arc Privacy, offering enterprises an optional on-chain privacy solution; and Aztec Network’s Alpha mainnet has been live on Ethereum for over two months.
Privacy is moving from concept to infrastructure.
This is precisely the story told in Castle Labs' newly released report, "The Full-Stack Privacy Ecosystem." Authorized by BlockWeeks, this report provides a systematic overview of the complete landscape, from L1 privacy chains to application-layer privacy protocols, covering the four core technologies—ZK, FHE, MPC, and TEE—and their real-world implementations within ecosystems such as Ethereum and Solana.
I. From "Mixers" to "Programmable Privacy": The Maturation of the Tech Stack
The earliest representatives of the privacy赛道 are privacy coins such as Monero and Zcash. Monero achieves default privacy through stealth addresses, ring signatures, and ring confidential transactions; Zcash, on the other hand, offers optional shielded transactions using zk-SNARKs. However, the limitations of privacy coins are evident: they primarily address privacy in "holding," not in "using."
The true paradigm shift occurs at the level of programmable privacy.
Railgun is a prime example. It is not merely a mixer, but a privacy-focused DeFi protocol running on the EVM that allows users to hide transaction data while preserving asset composability. Users can “shield” assets into Railgun’s private balances, then conduct private transfers, private swaps, and private DeFi interactions—all of which generate “noise” within the privacy pool, enhancing privacy for everyone. To date, Railgun has facilitated over $5 billion in transaction volume.
Aztec Network represents another path—achieving programmable privacy at the L2 layer. In March 2026, Aztec’s Alpha mainnet officially launched. Its core innovation lies in executing private functions within a private execution environment on the user’s device, generating a proof that is then submitted for on-chain verification. This means even Aztec’s sequencer cannot see the contents of your transactions. Aztec also supports “composable privacy”—applications can freely choose which states are public and which are private.
The STRK20 standard on Starknet is also worth noting. It enables shielded balances and private transfers for any ERC-20 asset on the network, while incorporating built-in compliance disclosure mechanisms. More importantly, it compresses what was previously a multi-step confidential exchange into a single atomic operation, fundamentally eliminating the possibility of MEV front-running.
II. FHE, MPC, and TEE: The "Three Musketeers" of Privacy Technologies
If ZK proofs address the problem of "verifying without revealing," then the next generation of privacy technologies is aiming to solve a broader challenge: performing computations directly on encrypted data.
Fully homomorphic encryption (FHE) is the standout among them. FHE enables processing of data while it remains fully encrypted, allowing servers to perform computations and return results without ever “seeing” the data. Octra has built an FHE-native L1, and its proprietary Hypergraph FHE splits encrypted data into localized regions for independent computation, overcoming the performance bottlenecks of traditional serial FHE processing. Fhenix employs a coprocessor model to provide privacy-as-a-service for Ethereum, Arbitrum, and Base. Zama’s fheVM library enables developers to create confidential smart contracts directly in Solidity.
Multi-party computation and trusted execution environments offer an alternative approach. Arcium uses MPC to split and distribute data across independent node clusters, where nodes collaboratively compute results without ever seeing any individual’s input. Since the Alpha mainnet launched in February 2026, Arcium has processed over 900,000 computations and 3.5 million transactions. Magic Block leverages TEEs (Intel TDX enclaves) to create “private temporary Rollups,” aggregating and processing transactions within a hardware-verified black box.
Notably, the report explicitly states that the final privacy stack will not be the victory of a single technology, but rather a combination of multiple technologies: FHE handles encrypted computation, MPC manages decentralized networks, and ZK verifies the correctness of inputs—each playing its role in synergy.
Three: Compliance and Privacy — The Difficult Transition from Opposition to Coexistence
The core tension in the privacy赛道 has always come from regulation.
The story of Tornado Cash is the ultimate expression of this tension. The 2022 OFAC sanctions, the arrest of its founders, and the upcoming retrial all send a clear signal: pure anonymity struggles to survive within existing regulatory frameworks.
But the industry did not retreat; it chose to evolve.
Privacy Pools was designed to directly address the legal challenges faced by Tornado Cash. The team "studied the lawsuits against Roman and Alexey, identified every point they were sued on, and then modified the protocol to mitigate those issues." It introduces "association set providers" to prevent illicit funds from entering the protocol, while using ZK proofs to allow users to prove their "cleanliness."
Railgun's "Proof of Cleanliness" system automatically generates ZK proofs in the background to verify that shielded tokens are not on a predefined blacklist.
The STRK20 integrity committee, controlled by threshold governance, holds the encryption viewing key to reconstruct user history upon legitimate request without accessing any other data in the pool—compared to Swiss banking confidentiality.
The Ethereum Foundation is also taking action. The Kohaku Privacy SDK enables wallets to easily integrate features such as private transfers and IP tracking protection. As the Ambire team stated: “For many wallets, these privacy features have always been an afterthought. Now Kohaku makes adopting them easy.”
Privacy and compliance are evolving from a zero-sum game to programmable coexistence.
Four: Panoramic Scan: The Complete Landscape of the Privacy Ecosystem
Castle Labs' report categorizes the privacy ecosystem into five layers:
L1 privacy chain: Represented by Monero and Zcash, privacy is baked into the consensus layer. But Zcash’s vulnerability incident exposed a deeper paradox—auditing privacy systems is inherently challenging.
Ethereum privacy: Protocols such as Tornado Cash, Railgun, and Privacy Pools enable Ethereum users to achieve privacy in transactions and DeFi interactions.
L2 Privacy: Aztec and Starknet natively support private states at the L2 level.
Cross-chain application layer: Secret Network (TEE + confidential computing), Oasis (confidential ParaTime), Near confidential Intents (hardware-enforced private execution environment), among others.
Solana’s privacy ecosystem: from Arcium’s privacy-preserving computation, Umbra’s encrypted token accounts, and encrypt.trade’s private transaction routing, to Melee’s private prediction markets and Loyal’s private AI.
Helius CEO Mert noted in the report that a mature privacy ecosystem "should have at least two very large privacy pools, or a single pool that is clearly decentralized with multiple configurable options. Formal verification, the absence of a committee, and immutability are non-negotiable."
Five: The Future Is Here: Privacy Will Become a Standard Feature of Financial Infrastructure
Castle Labs' report provides a clear assessment: "Privacy is no longer just about hiding transactions—it is increasingly becoming a requirement for usable financial infrastructure."
This judgment is based on several irreversible trends:
First, the expansion of digital surveillance is irreversible. AI has brought the cost of data collection and analysis close to zero, and predictive monitoring is transitioning from theory to reality. The advancement of CBDCs will further shrink the space for private transactions. Privacy infrastructure must be in place before demand becomes urgent.
Second, institutions require privacy. Institutions cannot expose their balances, counterparties, order flow, payroll, and customer data on public ledgers. The Solana Foundation released a privacy framework report for institutions in March 2026. Circle’s Arc Privacy directly addresses this need. As the report states: “On-chain finance cannot mature if every meaningful action is publicly visible by default.”
Third, privacy is shifting from “opt-in” to “default.” The Kohaku SDK enables wallets to easily integrate privacy features; STRK20 makes assets privacy-native from issuance; Railgun aims to “become infrastructure embedded in wallets, like TLS and SSL, so people don’t even know it’s there.”
Fourth, technical bottlenecks are being overcome. FHE performance is rapidly improving; although client proof costs remain high on Aztec, the roadmap is clear; the combined use of ZK, FHE, MPC, and TEE is creating privacy protections far surpassing those of any single technology.
Conclusion
The Zcash vulnerability crisis and the reconsideration of Tornado Cash were two storms facing the privacy sector in mid-2026. Yet beneath these storms, a deeper trend is emerging: privacy is transitioning from a "feature" to "infrastructure," from an "option" to a "default," and from "regulatory resistance" to "regulatory readiness."
The report "Full-Stack Privacy Ecosystem," jointly released by Castle Labs and BlockWeeks, provides the most systematic panoramic overview of this transformation to date. Whether you are a developer, investor, or observer, understanding the various layers of the privacy stack and their interrelationships will be essential to grasping the next generation of blockchain infrastructure.
Privacy is not a tool for criminals. It is the foundation of freedom, a prerequisite for institutional access, and a necessity for financial maturity.
And this transformation has only just begun