Turing completeness in blockchain. What is it? | OWNR Wallet

Back to Blog

Understanding Turing Completeness in Blockchain Technology

In the realm of computer science and blockchain technology, the term "Turing completeness" refers to a system's capability to perform any computation that a Turing machine, a theoretical model of computation, can achieve. This concept, rooted in the work of British mathematician and logician Alan Turing in 1936, establishes a benchmark for computational universality.

A Turing-complete machine encompasses all essential functions necessary for universal computation. It can manipulate various data types, such as lists, words, and numbers, while supporting repetition through loops and decision-making through directives like "if-else" statements. Additionally, it provides methods for retrieving and storing data from memory, paving the way for a myriad of computational possibilities and allowing the expression of any algorithmic calculation.

In the context of blockchain technology, Turing completeness is a coveted feature as it empowers a blockchain platform to handle diverse applications and smart contracts. Smart contracts, self-executing lines of code with embedded conditions, can articulate intricate logic and execute a broad spectrum of computational activities due to the Turing completeness of blockchain platforms.

Ethereum, a prominent blockchain technology platform, exemplifies Turing completeness. Its programming language, Solidity, enables developers to craft complex decentralized applications (DApps) and smart contracts, revolutionizing the landscape of blockchain-based applications.

In 2012, Silvio Micali, a distinguished figure in computer science, was awarded the Turing Award for his contributions. Micali's application of Turing completeness in developing the Algorand blockchain stands as a testament to his groundbreaking work. Algorand showcases the utilization of Turing-complete algorithms in decentralized networks, featuring a unique consensus mechanism and scalability capabilities.

While complete blockchains enable the creation of versatile applications, they also demand a meticulous approach to programming, testing, and security for effective utilization of their benefits.

Turing Completeness and Its Implications for Smart Contracts

At its core, Turing completeness empowers smart contracts to be potent, expressive, and adaptable computational entities, transforming the landscape of DApps on blockchain platforms.

This fundamental notion in computer science holds significant consequences for blockchain-based smart contracts, signifying a system's global programmability akin to a Turing machine. This attribute provides an immense degree of flexibility and sophistication to smart contracts, allowing them to express and execute complicated algorithms on Turing-complete blockchain systems like Ethereum. Turing completeness introduces various implications for smart contracts, enabling the creation of flexible and dynamic contracts that go beyond simple transactional procedures. However, this power comes with the responsibility to ensure security and predictability during development and auditing, addressing potential issues like infinite loops.

The notion fosters creativity among developers, allowing exploration and implementation of a diverse range of applications, contributing to the development of decentralized ecosystems.

The Role of the Ethereum Virtual Machine (EVM) in Ethereum's Turing Completeness

The Ethereum Virtual Machine (EVM) plays a pivotal role in expressing complex computations and sophisticated decentralized applications on the Ethereum blockchain.

Functioning as the smart contract execution environment on the Ethereum network, the EVM is instrumental in achieving Turing completeness. It empowers programmers to create and run DApps using Solidity, Ethereum's native programming language intentionally designed to be Turing-complete. The gas mechanism within the EVM is a noteworthy feature, controlling computing resources and ensuring stability by requiring users to pay for resources used. This prevents abuse and resource-intensive processes, maintaining the network's effectiveness. The EVM's compatibility facilitates seamless communication among different smart contracts, enhancing the potential for complex and networked decentralized systems.

In summary, the Ethereum Virtual Machine is crucial to Ethereum's Turing completeness, enabling a broad range of DApps and solidifying Ethereum's position in the blockchain industry.

Is the Bitcoin Blockchain Turing-Complete?

No, the Bitcoin blockchain is deliberately not Turing complete. Bitcoin's scripting language is intentionally designed to lack the full expressive capabilities of Turing completeness, while still allowing for some level of programmability.

The scripting language used by Bitcoin, known as Bitcoin Script, is purposely Turing incomplete. This design choice aligns with Bitcoin's primary objective of serving as a decentralized digital currency system rather than a platform for intricate programmability. Bitcoin Script aims to prioritize security and avoid potential vulnerabilities associated with Turing completeness.

The inherent risks of undecidable calculations or infinite loops, which can be exploited maliciously, are minimized by the non-Turing completeness of Bitcoin's scripting language. This design ensures that scripts run predictably and terminate within a reasonable timeframe.

Bitcoin operates on a decentralized consensus mechanism, requiring all nodes on the network to agree on the state of the blockchain. Turing completeness could introduce non-deterministic behavior, complicating consensus-reaching among nodes. By maintaining a non-Turing-complete programming language, the Bitcoin blockchain ensures predictable execution and consistent consensus.

Various programming languages, such as JavaScript, Python, Java, and Ruby, are Turing complete, enabling the execution of arbitrary algorithms. Other Turing-complete blockchains, apart from Ethereum, include Tezos with Michelson, Cardano with Plutus, NEO supporting multiple languages, and BNB Smart Chain compatible with Ethereum's Solidity.

Drawbacks of Turing-Complete Blockchains

Despite offering significant flexibility and processing capacity, Turing completeness in blockchains comes with intrinsic disadvantages that should be carefully considered.

One major drawback is the potential for unforeseen effects and vulnerabilities. The same flexibility that allows for complex computations also introduces the risk of coding mistakes, security flaws, or unforeseen interactions between smart contracts, which could lead to disastrous consequences. The 2016 Ethereum blockchain incident, known as the decentralized autonomous organization (DAO) hack, serves as an example of the exploitation of unanticipated flaws in Turing-complete smart contracts, resulting in significant monetary losses.

Additionally, speed and scalability issues may arise from Turing completeness. Intricate calculations on each network node could overload the system, affecting transaction efficiency and speed. The general stability and dependability of the blockchain network are jeopardized due to the potential for infinite loops or resource-intensive procedures.

Formal verification becomes more challenging with Turing-complete blockchains, as they allow any computable function. Unlike simpler, non-Turing-complete systems, verifying program correctness becomes computationally difficult. Smart contract security on a Turing-complete blockchain requires complex auditing procedures and advanced tools.

Share this article

We use cookies to improve your experience. By closing this message you agree to our Cookies Policy.