Mainstream Adoption Won’t Happen on Public Chains

Bitcoin solved a problem that had stumped computer scientists and bankers for decades: how to transfer value between strangers, without a trusted intermediary. It was a genuine breakthrough, and 15 years later, the financial world is still wrestling with what to do with it.

Ethereum took blockchains to another level, offering programmable value alongside value transfer: smart contracts that could encode agreements, automate settlement, and eliminate entire categories of middlemen. 

Then came stablecoins, which married the programmability of crypto to the stability of the dollar. From there, the migration of real-world assets to onchain protocols began. 

Each wave has brought added institutional interest, capital, and ambition. And, now, as regulatory clarity emerges, institutions are ready to deploy resources onchain.

But, there’s one big thing holding them back: the vast majority of these early blockchains share a fundamental flaw that becomes ever more consequential the larger the numbers get.

Everything is visible. Every wallet. Every balance. Every transaction, in real time, is readable by anyone with a browser. And with the increasing sophistication of AI, the digital trail left behind by public blockchains is going to become more of a liability than ever.

We are accustomed to thinking that transparency onchain is a benefit and feature. But, in financial markets, hosting an entire infrastructure on a public network is unthinkable. Imagine if every hedge fund's positions, every corporate treasury's holdings, every pension fund's rebalancing trade appeared on a public screen the moment it was executed. Sophisticated counterparties would surely front-run. Why not? Competitors would map your fund’s strategy. Criminals would identify targets and pounce. The financial system as it is today would seize up overnight.

Blockchains have been asking institutions to accept exactly that. 

Imagine, major asset holders initiate an asset transfer, only to find themselves outpositioned within seconds. Treasury teams discover their onchain activity is being tracked and analyzed in real-time. In some sense, that’s the point. The self-policing ethos of many blockchain projects means “surveillance” is structural, shrugging off the need for external oversight.  

Why ZK matters

Zero-knowledge (ZK) cryptography changes the calculus. ZK proofs allow a user to prove that a transaction is valid without revealing underlying data. It means entities onchain can reveal just what they need to prove for a transaction, rather than their wider financial profile (e.g. their positions, balances, etc). 

Miden, a new ZK-native blockchain, builds this privacy-preserving functionality into the execution layer itself. Accounts execute transactions locally on users' devices, and the chain only stores the cryptographic commitment; nothing sensitive ever touches a public ledger. On our infrastructure, no transaction history is browsable, allowing complete anonymity and protection of user data. 

This next evolution of blockchains solves the fundamental problem of privacy in a practical way. If Bitcoin gave us trustless transfer and Ethereum gave us programmable trust, Miden offers verifiable privacy: the ability to prove that everything happened correctly without revealing what actually happened.

Miden Guardian: a backend for privacy‍

But bringing true privacy onchain isn’t just a technical challenge. It’s an operational one. Implementing it means a fundamental change in the prevailing architecture of blockchains today. 

Transparency is intrinsic to how most blockchains function. It is the coordinating principle of how most blockchains are designed, and creates several levels of operating assumptions. For example, multisig approvals assume shared visibility, fraud monitoring assumes readable balances, and compliance workflows assume an auditable trail.

In seeking privacy for institutions, many providers have taken the obvious step: strip away the public ledger. But that introduces a new problem – what we call the “privacy paradox.” The same property (transparency) that makes a blockchain secure (because everyone has visibility) also makes them hard to operate.

Say a signer's key is compromised in a transparent system. Unusual onchain activity would trigger alerts, making the network aware of the issue. 

By contrast, in a private-by-default system, there's no public balance view, no browsable history – only commitments. Unless operators enact robust offchain safety mechanisms, attackers can move quietly and steal funds without anyone the wiser.

Miden's answer is Guardian, an institutional backend layer and our first “practical privacy” product.

‍How does it work?‍

Guardian synchronizes users’ account state before each transaction, effectively hosting a continuously updated backup of the account. It doesn’t store the assets themselves, only the cryptographic state required to access and operate them.

This distinction is everything. Guardian never takes custody and holds no keys, controls no funds, and cannot unilaterally move assets. Instead, it provides the coordination and safety layer that makes privacy operationally viable at institutional scale.

Think of it as the difference between a bank vault and a bank's alarm system. The alarm system doesn't hold your money. It ensures that if something goes wrong, you know about it.

Guardian does the same for private blockchain accounts: backup and multi-device recovery, so a lost device doesn't mean lost access; policy enforcement, enabling rate limits, transaction delays, and account freezes without requiring onchain visibility; and compliance integration, so institutions can satisfy regulatory obligations without surrendering custody or exposing activity to the public ledger.

Blockchains with compliant privacy‍

In the past, compliance and privacy have been seen by regulators and many institutions as incongruous, like oil and water. But in the next evolution of blockchains, regulatory compliance won’t require full transparency such that everyone can see your transactions. It will require only that the right parties, under the right conditions, can verify that your transactions were legitimate.

Guardian is built around precisely this distinction.

The financial industry is approaching a crossroads. It knows it needs to move onchain, but the baked-in transparency of older blockchain makes adoption of decentralized systems risky and uncertain. It’s essential to enable genuine privacy, but not at the cost of control, recoverability, or compliance.

With Miden Guardian, users retain control of their assets, and institutions get the safety, recovery, and compliance infrastructure they require. For the first time, institutions are empowered to embrace blockchain’s promise without having to operate in public.