Security Analysis of Move Language

Move language, as a new generation smart contract language, has taken into account the security issues of blockchain and smart contracts from the very beginning of its design. This article will analyze the security of Move language from three aspects: language features, operating mechanisms, and verification tools.

1. Security Features of Move Language

The Move language has discarded many flexible but unsafe features, such as dynamic dispatch and recursive external calls, and instead adopted concepts like generics, global storage, and resources to achieve a safe programming model.

The main security features of Move include:

• Modularization: Each module consists of structural types and process definitions, and can import types from other modules and call processes from other modules.

• Resource Type: The resource type is defined using the has key syntax and can be stored in the global key-value store.

• Global Storage: Allows for persistent data storage, accessible only by the module that owns it.

• Access control: It can restrict specific addresses from calling certain processes.

• Invariant reduction: allows the definition of invariants for static checks to ensure the conservation of state.

• Bytecode verification: Enforce the type system at the bytecode level to prevent illegal operations.

These features enable Move to support the writing of programs that allow for secure interactions and support static verification.

2. The Operating Mechanism of Move

The Move program runs in a virtual machine and cannot directly access system memory. Its state consists of the call stack, memory, global variables, and operand stack.

Main operation mechanism:

• Stack-based execution: easy to implement and control, suitable for blockchain scenarios.

• Resource linearization: Resources can only be moved, not copied.

• Static jump: does not support dynamic dispatch, avoiding reentrancy issues.

• Data and logic separation: User status and program logic are stored separately, enhancing security and execution efficiency.

3. Move Prover

Move Prover is a formal verification tool based on deductive verification that can automate the auditing of smart contracts.

Main Features:

• Use formal languages to describe program behavior.
• Use SMT solvers to verify program correctness.
• Supports the independent specification language Move Specification Language.
• Can generate source-level error reports.

Move Prover helps ensure contract correctness and reduce transaction risk.

Summary

The Move language has made comprehensive security considerations in terms of language features, virtual machine execution, and security tools. It can effectively avoid common vulnerabilities such as reentrancy and overflow, but third-party audits are still needed to ensure overall security. Although Move provides a good security foundation, developers still need to remain vigilant to ensure the security of the code.