Understanding Closed-Loop Tokens: Enhanced Security and Customization

Closed-Loop Tokens (CLTs) are emerging as a crucial innovation in the blockchain space, offering enhanced security, compliance, and tailored functionality for specific applications, according to The Sui Blog.

The Need for Closed-Loop Tokens

While the unrestricted nature of the Sui Coin standard is valuable for many use cases, it falls short in scenarios requiring specific constraints. For example, certain applications may need tokens that can only be used for particular purposes, by authorized accounts, or within specified marketplaces. Loyalty programs, in-game currencies, and restricted marketplaces often benefit from controlled environments where tokens cannot be traded or used outside their intended context.

Regulatory compliance also necessitates restrictions on token usage to ensure that only verified or authorized entities can hold and use these tokens. Implementing such controls helps mitigate the risk of misuse, fraud, and regulatory breaches, creating a secure economic system with enforceable rules and restrictions.

Opportunities Unlocked by Closed-Loop Tokens

CLTs empower developers with a higher degree of control and customization over how tokens are used and transferred within their applications. Using the CLT standard in the Sui framework, developers can:

• Restrict token usage to authorized applications.
• Set up custom policies for transfers, spends, and conversions.
• Add arbitrary restrictions on token transfers between user addresses, spending tokens, and token usage in smart contracts.

These capabilities enable a wide range of possibilities. For instance, tokens can be designed to prevent on-chain trading, making them ideal for loyalty programs or in-game currencies where speculation is undesirable. They can also ensure compliance with regulatory requirements by restricting usage to verified accounts or specific services.

How Closed-Loop Tokens Work

Builders implement CLTs through the sui::token module, which distinguishes them from traditional coins by their lack of the store ability. This means CLTs cannot be wrapped, stored as dynamic fields, or freely transferred unless a custom policy allows it. They can only be owned by an account and not stored in an application, but they can be spent.

The authorization mechanism for CLTs is called an ActionRequest, allowing the token owner to specify which actions (transfers, spends, conversions) are permitted and enforceable through predefined rules. A TokenPolicy is a shared object that the token creator can generate using the TreasuryCap, specifying the conditions for token transfers, spends, or conversions. These policies are enforced by programmable rules within the TokenPolicy, implemented as separate Move modules, allowing for modular and reusable policy definitions.

To address token storage issues, CLTs utilize a spend method, where spent tokens can either be burned directly or delivered to the TokenPolicy as spent_balance. This balance cannot be reused and can only be burned, ensuring strict control over token lifecycle and usage.

Closing the Loop

Closed-Loop Tokens offer a level of control and customization not possible with the Sui Coin standard or typical token standards found on other blockchain protocols. By enabling developers to impose specific rules and restrictions on token usage, CLTs open up new possibilities for secure, compliant, and specialized applications. The adoption and implementation of CLTs are expected to play a crucial role in shaping the future of DeFi and digital assets.

Note: This content is for general educational and informational purposes only and should not be construed or relied upon as an endorsement or recommendation to buy, sell, or hold any asset, investment, or financial product and does not constitute financial, legal, or tax advice.

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