Move: The Security Powerhouse of Blockchain Smart Contracts

A New Era of Secure Smart Contracts

Imagine you’re locking your crypto assets inside a vault. Would you choose one with a fragile glass door (Solidity) or one made of unbreakable steel (Move)?

Solidity, the most widely used language for Ethereum smart contracts, has powered countless decentralized applications (dApps). But it has also been the root cause of billions of dollars lost to hacks, reentrancy attacks, and contract vulnerabilities.

Enter Move, a next-gen programming language built with security, verifiability, and scalability in mind. Originally designed for Diem (Facebook’s blockchain), Move is now the backbone of Movement Labs Aptos and Sui, It solves Solidity’s fundamental security issues while introducing parallel processing, resource-based ownership, and formal verification—all of which redefine how smart contracts work.

Solidity’s Security Pitfalls: Why We Need Move

Solidity has been around for nearly a decade, but its security flaws have led to some of the biggest disasters in blockchain history.

The DAO Hack (2016) – $60M Lost

The reentrancy attack is Solidity’s biggest nightmare. It’s like an ATM allowing you to withdraw money before checking your balance—letting hackers drain funds infinitely.

Here’s how the vulnerability looked in Solidity:

contract VulnerableDAO {
    mapping(address => uint) public balances;

    function withdraw(uint _amount) public {
        require(balances[msg.sender] >= _amount);
        (bool success, ) = msg.sender.call{value: _amount}(""); // 🔥 Reentrancy issue
        require(success);
        balances[msg.sender] -= _amount; // ❌ This should be updated BEFORE sending ETH
    }
}

A hacker loops the withdraw function before the contract updates its balance, draining all funds.

Result: The DAO lost $60 million, and Ethereum was forced to hard fork to reverse the damage.

The Parity Multisig Bug (2017) – $300M Frozen Forever

Another Solidity horror story—a simple coding mistake in a multisig wallet allowed someone to accidentally destroy all wallets using the contract.

contract KillSwitch {
    function kill() public {
        selfdestruct(payable(msg.sender)); // 💀 Fatal flaw: anyone can call this!
    }
}

By executing selfdestruct(), someone wiped out access to $300M in ETH, locking it forever.

How Move Solves Solidity’s Problems

Move was built to fix these flaws at the language level, making smart contracts inherently secure, efficient, and verifiable.

Move Eliminates Reentrancy Attacks

Unlike Solidity, Move enforces ownership and resource safety at the type system level.

Here’s a secure version of a withdrawal function in Move:

module SecureBank {
    struct Balance has key { amount: u64 }

    fun withdraw(account: &signer, amount: u64) {
        let balance = borrow_global_mut<Balance>(signer::address_of(account));
        assert!(balance.amount >= amount, 100);
        
        balance.amount = balance.amount - amount; // ✅ Balance updated first
        // No external call possible until function exits!
    }
}

Why is this safe?

• No external calls before updating state
• No reentrancy risk
• Resources (tokens) are owned, not just stored as numbers

Move Prevents Contract Destruction

Move does not allow selfdestruct(), meaning contracts cannot be accidentally killed. Once deployed, they live forever unless explicitly updated through a controlled upgrade path.

Formal Verification: Proving Code is Hack-Proof

Move goes beyond fixing Solidity’s issues—it proves mathematically that smart contracts will behave correctly.

Formal verification allows developers to mathematically prove that their code follows expected rules and is free of vulnerabilities.

Move’s linear type system makes proving correctness easier by ensuring:

• No double-spending of assets
• No unauthorized state modifications
• No reentrancy bugs

Solidity is slowly catching up, introducing tools like VeriSol and MythX, but these are external tools, while Move’s verification is built-in by design.

Move vs. Solidity: A Security Showdown

Advanced Features: Memory Management & Parallel Processing

Memory Management: Move’s Ownership Model

Solidity’s memory system relies on garbage collection—which introduces inefficiencies and security risks.

Move uses ownership-based memory management, where assets are actual resources that:

• Can’t be copied (No double-spending)
• Can’t be accidentally deleted (No loss of assets)
• Are explicitly owned and transferred

Example: Defining a resource in Move

struct Token has key, store {
    value: u64
}

Once a token is moved, it can’t be accessed from the previous location. This prevents errors like double-spending, a common issue in Solidity.

Parallel Processing: Move’s Hidden Superpower

Ethereum (Solidity) runs on a single-threaded execution model, meaning transactions happen one at a time.

Move enables parallel transaction execution, meaning multiple transactions can be processed simultaneously—resulting in:

• Faster block confirmations
• Lower gas fees
• Better scalability

This is why Aptos, Nexio, Movement Labs, and Sui can process thousands of TPS while Ethereum struggles at 20-30 TPS. 

Move: Solving Bitcoin’s Programmability Problem

In a world where Bitcoin is famed for its security but lacking in programmability, Nexio’s adoption of Move is a game-changer. Here's why Move is our secret sauce for overcoming Bitcoin’s limitations:

Built-In Formal Verification with Move Prover

One of the standout features of Move is the Move Prover. This tool acts as an automated auditor that mathematically proves that your smart contracts behave exactly as intended—catching issues like integer overflow, division by zero, and reentrancy bugs before deployment.

Real-World Analogy:
Imagine you’re building a skyscraper. Instead of relying solely on visual inspections, you run detailed mathematical simulations to ensure the structure can withstand extreme conditions. The Move Prover does the same for your smart contract code, offering a guarantee that there are no hidden vulnerabilities.

Example Code with Move Prover:

Below is an example of a simple counter contract in Move. Notice the use of a spec block that defines expected behavior, which the Move Prover checks for correctness.

module my_addrx::Example {

    struct Counter has key {
        value: u8,
    }

    public fun increment(a: address) acquires Counter {
        let c = borrow_global_mut<Counter>(a);
        c.value = c.value + 1;
    }

    spec increment {
        // Ensure the function aborts if the counter is at its maximum value (255),
        // which would cause an overflow.
        aborts_if global<Counter>(a).value == 255;
        // After a successful increment, the counter's value should increase by 1.
        ensures global<Counter>(a).value == old(global<Counter>(a)).value + 1;
    }
}

In this example, if you try to increment a counter that’s already at 255, the aborts_if clause kicks in to prevent an overflow. The Move Prover automatically checks this specification—so if there’s any error (like missing conditions), it will flag it immediately. This built-in verification process makes smart contracts written in Move far more trustworthy.

Parallel Execution for High Throughput

Bitcoin’s traditional model is inherently sequential, meaning it can’t process transactions in parallel. This is a bottleneck for scaling. Move, however, supports parallel processing:

• MoveVM & BlockSTM: Nexio uses these advanced systems to execute transactions concurrently. This means multiple transactions run at the same time, leveraging multi-core processors and significantly boosting throughput—up to an impressive 30,000 TPS.‍
• Efficiency in Execution: By processing transactions in parallel, Move not only reduces delays but also cuts down on energy consumption. It’s like having multiple checkout lanes at a busy store instead of just one, speeding up the entire process.

Seamless Developer Experience and Interoperability

Nexio’s infrastructure takes advantage of Move’s ability to work with both EVM and Move environments. Thanks to our special tool, Fractal, developers can write smart contracts in Solidity and have them converted to secure MoveVM bytecode. This dual compatibility means:

• Low Friction Onboarding: Developers from both the Ethereum and Move ecosystems can jump into building on Nexio without having to learn a completely new system from scratch.
• Robust Interoperability: By abstracting the complexity of cross-chain interactions, Nexio provides a unified environment where assets move securely and efficiently across different blockchain networks.

Why We Chose Move for Nexio

At Nexio, our mission is to unlock Bitcoin’s potential for global-scale decentralized finance by overcoming its inherent programmability limitations. Move addresses these challenges head-on:

• Superior Security: Its resource-oriented design, combined with built-in formal verification, ensures that our smart contracts are rock-solid.
• High Performance: Parallel execution through MoveVM and BlockSTM means Nexio can handle massive transaction volumes without breaking a sweat.
• Enhanced Developer Experience: With tools like Fractal bridging the gap between Solidity and Move, developers can build on Nexio with minimal friction, paving the way for innovative dApps that tap into Bitcoin’s security and scalability.

Final Thoughts: Move is the Future of Smart Contract Security

As a developer, your goal is to build innovative dApps without constantly worrying about security flaws. Move shifts your workflow from reactive patching to proactive innovation—letting you code confidently from day one. Instead of navigating Solidity’s hidden risks, Move offers built-in verification and clear structures to securely scale your projects. Spend less time fixing vulnerabilities and more time innovating.