Tech Talk: Arcium - Fully Encrypted Solana Execution

What if the only way to access your private blockchain data was to win a Nobel Prize in mathematics? That's the level of cryptographic security Arcium is bringing to Solana, and it could fundamentally change how we think about privacy on public blockchains.

At Breakpoint 2025, Arcium's Nico Schapeler unveiled how their "encrypted supercomputer" enables fully private computation on Solana using secure multi-party computation (MPC). With an ambitious goal of encrypting the majority of Solana's transactions per second by the next Breakpoint conference, Arcium is positioning itself as the infrastructure layer that could finally solve blockchain's transparency problem.

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Summary

Arcium represents a paradigm shift in blockchain privacy by enabling fully encrypted execution on Solana without requiring users to move their assets off-chain or trust centralized third parties. Unlike traditional privacy solutions like mixers that still leak statistical information, Arcium's approach provides zero-information leakage through cryptographic guarantees that make it mathematically impossible for adversaries to extract private data.

The technology works by splitting encrypted data into "MPC secret shares" that are distributed across multiple nodes in the Arcium network. Each individual share reveals absolutely nothing about the underlying data, but when combined through secure multi-party computation, the nodes can perform arbitrary computations and return encrypted results—all without any single node ever seeing the actual data.

What makes Arcium particularly compelling for the Solana ecosystem is its native compatibility. Your smart contracts still live on Solana, your state remains on-chain, and execution happens through Solana's infrastructure. The only difference is that observers—including block explorers, validators, and potential attackers—only ever see encrypted ciphertext rather than your actual transaction data or account balances.

The security model is remarkably robust. Arcium's in-house MPC backend, called Cerberus, provides "dishonest majority" and "malicious security" guarantees. This means that even if all but one node in the network is compromised and actively malicious, the system still produces valid outputs and keeps data private. Developers who want maximum assurance can even run their own node, guaranteeing at least one honest participant in the network.

Key Points:

Why Blockchain Privacy Matters Now More Than Ever

The transparency of public blockchains, long considered a feature, has become a serious liability as the ecosystem matures. Schapeler highlighted multiple real-world concerns that Arcium directly addresses. Over the past 18 months, there have been numerous physical attacks against crypto holders who were targeted specifically because their on-chain balances were publicly visible. When attackers can simply check a block explorer to identify high-value targets, wealth transparency becomes a security vulnerability.

Beyond personal safety, the lack of privacy creates significant barriers for institutional adoption. Traditional finance entities and enterprises often have legal requirements around data confidentiality that make fully transparent blockchains unsuitable for their needs. Currently, these organizations are forced to keep sensitive data off-chain and only interface with Solana for specific operations, relying on trusted third parties that reintroduce the centralization that blockchain was designed to eliminate.

How Secure Multi-Party Computation Enables Private Blockchain Execution

The technical magic behind Arcium lies in secure multi-party computation, a cryptographic technique that allows multiple parties to jointly compute a function over their inputs while keeping those inputs private. Here's how it works in practice: when you want to store private data on Solana, you encrypt it and upload the ciphertext to your account. Anyone viewing the block explorer sees only encrypted gibberish, not your actual data.

When you need to compute on this data—say, add five to a number—Arcium splits the encrypted data into MPC secret shares. Each share is mathematically designed so that it reveals zero information about the original secret, but when combined, they reconstruct the data perfectly. These shares are distributed to different nodes in the Arcium network, which perform the computation using the Cerberus MPC backend. The nodes produce results that are re-encrypted before being returned to Solana, meaning the private data is never exposed at any point in the process.

Cerberus: The Cryptographic Engine Powering Arcium

Arcium's cryptographers developed Cerberus specifically for general-purpose MPC, setting it apart from the signature-focused MPC implementations most people associate with the technology. Cerberus can compute any arbitrary function, from DeFi operations to complex smart contract logic, all while maintaining cryptographic privacy.

The security guarantees are particularly notable. "Dishonest majority" means you only need to trust that a single node in the entire cluster is honest—a much weaker assumption than the 51% or 66% thresholds common in blockchain consensus. "Malicious security" assumes that compromised nodes can do literally anything: go offline, send incorrect data, or actively attack the network. Even under these conditions, Cerberus ensures no invalid outputs are produced and no private data is leaked. For developers who want absolute certainty, running their own node guarantees they meet the honest minority threshold.

Arcis: Making Encrypted Programming Accessible

Perhaps the most developer-friendly aspect of Arcium is Arcis, the first Rust-to-MPC bytecode compiler. Recognizing that most blockchain developers aren't cryptographers, Arcium designed a development experience that requires no specialized knowledge. Developers write standard Rust code, annotating encrypted inputs and outputs with a simple generic struct, and the compiler handles the complex transformation to Cerberus bytecode.

Schapeler demonstrated this with a voting program example that looked almost identical to conventional Rust code. The only visible difference was the "ink" generic wrapper around inputs and outputs indicating encryption. This dramatically lowers the barrier to entry for privacy-preserving applications—if you know Rust, you can build on Arcium. The compiled bytecode deploys directly to Solana, maintaining full compatibility with the existing ecosystem.

MEV Protection Through Encryption

Maximum Extractable Value (MEV) represents one of the most contentious issues in blockchain, where validators and searchers exploit their ability to see pending transactions to extract value through front-running, sandwich attacks, and other strategies. Arcium's encryption approach offers a fundamental solution: if validators can't see what state changes a transaction will produce, they can't profitably extract value from it.

While Schapeler was careful not to claim this solves 100% of MEV issues given the problem's complexity, he noted that for the most common MEV vectors—particularly sandwich attacks—encryption is highly effective. This could represent a significant improvement in user experience and fairness, as users would no longer need to worry about sophisticated actors extracting value from their trades.

Facts + Figures

• Arcium's goal is to have the majority of Solana's TPS be encrypted by the next Breakpoint conference
• The security model requires only 1 honest node out of the entire cluster, compared to 51% or 66% thresholds in typical blockchain consensus
• Cerberus provides both "dishonest majority" and "malicious security" guarantees simultaneously
• Arcis is the first Rust-to-MPC bytecode compiler, allowing developers to write encrypted programs in standard Rust
• The technology enables zero-information leakage, unlike mixers which can be analyzed statistically
• All state, accounts, and smart contracts remain on Solana—no off-chain infrastructure required
• Real-world attacks against crypto holders have increased over the past 18 months, targeting victims based on visible on-chain balances
• MPC secret shares individually reveal zero information about the underlying secret
• The encryption covers inputs, intermediary values, and outputs—complete end-to-end privacy
• Developers can run their own Arcium node to guarantee at least one honest participant in any computation

Top Quotes

"Your adversary would have to gain a Nobel Prize for breaking cryptography, basically, to be able to withdraw private information that you want to keep hidden."

"When we say hide everything, we mean everything, meaning inputs, intermediary values, outputs, the whole thing."

"If you deposit a thousand two hundred dollars into it and 10 seconds later withdraw $1,200 once more, it's quite obvious to an outside observer using statistical methods what you're doing."

"The individual nodes in the middle here, never learn what the private data is. They only ever see shares."

"Dishonest majority means that you have to trust that one node in the entire cluster is honest, as opposed to 51% or 66%."

"If you know Rust, you can use Arcium."

"Help us complete our mission of having majority of TPS on Solana be encrypted by next Breakpoint."

"You won't get targeted if someone doesn't know if you have $1 or a million dollars."

Questions Answered

What is Arcium and what problem does it solve?

Arcium is a network extension for Solana that enables private state and private execution using secure multi-party computation (MPC). It solves the fundamental transparency problem of public blockchains where anyone can see your account balances, transaction details, and other sensitive information. Unlike storing data off-chain with trusted third parties, Arcium keeps everything on Solana while ensuring only encrypted data is visible to observers. The technology provides cryptographic guarantees rather than relying on obfuscation techniques that can be reverse-engineered.

How does secure multi-party computation protect my data?

When you store encrypted data on Solana through Arcium, computations on that data work by splitting it into MPC secret shares distributed across multiple network nodes. Each individual share mathematically reveals zero information about the original data. The nodes perform computations on their shares using Arcium's Cerberus backend, producing results that are re-encrypted before returning to Solana. At no point does any single party—including the Arcium nodes, Solana validators, or external observers—ever see your actual unencrypted data. The only way to break this protection would be to solve mathematical problems that are considered computationally impossible with current technology.

What security guarantees does Arcium provide?

Arcium's Cerberus MPC backend provides two critical security properties: dishonest majority and malicious security. Dishonest majority means the system remains secure as long as just one node out of the entire cluster is honest—a much stronger guarantee than typical blockchain consensus requiring 51% or 66% honesty. Malicious security means the system assumes compromised nodes can take any adversarial action: going offline, sending incorrect data, or actively attacking the network. Even under these extreme conditions, invalid outputs are never produced and private data is never revealed.

Do I need to be a cryptographer to build with Arcium?

No, Arcium specifically designed their developer tools to be accessible to anyone who knows Rust. Arcis, their Rust-to-MPC bytecode compiler, allows developers to write standard Rust code with minimal modifications. The only difference from regular Rust programming is wrapping encrypted inputs and outputs with a generic struct. The compiler handles all the complex cryptographic transformations to Cerberus bytecode automatically. Your smart contracts still deploy to Solana and interact with the ecosystem normally.

Can Arcium prevent MEV attacks?

Arcium's encryption provides strong protection against common MEV vectors, particularly sandwich attacks. Since validators cannot see what state changes an encrypted transaction will produce, they cannot profitably front-run or back-run your trades. While Schapeler noted that MEV is a complex issue and encryption doesn't claim to solve 100% of cases, the most frequent types of value extraction become impossible when transaction contents are hidden. This represents a significant improvement in fairness for users who currently lose value to sophisticated MEV extractors.

What happens if I don't trust the Arcium network nodes?

Arcium's security model accommodates this concern elegantly. Because the system only requires one honest node for security guarantees to hold, you can simply run your own node in the cluster. This ensures that regardless of whether other nodes are trustworthy, at least your node is honest, fulfilling the dishonest majority requirement. This makes Arcium uniquely suited for applications where users or enterprises have strict trust requirements, as they can verify their own participation in the computation.