Coin Standard on Sui Blockchain: A Comprehensive Guide

The Coin Standard is the technical framework used for smart contract development on the Sui blockchain, enabling the creation of standardized digital coins. This standardization ensures seamless integration across wallets, exchanges, and smart contracts, allowing all Sui-created coins to be managed with the same logic as the native SUI token.

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Fungible Tokens on Sui

In Sui's ecosystem, the Coin type represents open-loop fungible tokens (distinct from closed-loop Token types). Key characteristics include:

• Type Parameter (T): Associates metadata (name, symbol, decimal precision) with each coin instance
• Interchangeability: Units of T are fungible, mirroring traditional fiat currency behavior

• Documentation Terminology:

  • "Coins" = Coin Standard creations
  • "Tokens" = Closed-Loop Standard creations

Treasury Capability: Minting and Burning

The TreasuryCap object governs coin supply management:

• Creation: Generated via coin::create_currency for contract publishers

• Functions:

  • coin::mint: Creates new tokens (auto-updates total supply)
  • coin::burn: Destroys tokens (enforces supply limits)
• Transferability: Can be transferred to third parties, relinquishing original creator control

Example Mint Function:

public fun mint(cap: &mut TreasuryCap, value: u64, ctx: &mut TxContext): Coin {
    Coin {
        id: object::new(ctx),
        balance: cap.total_supply.increase_supply(value),
    }
}

Regulated Coins Framework

Enhanced functionality for compliance-focused tokens:

Core Components

1. Creation: Via coin::create_regulated_currency_v2 which returns:

   • Standard CoinMetadata
   • Additional RegulatedCoinMetadata
   • DenyCapV2 capability

2. Deny List System:

   • Maintained in DenyList shared object (ID: 0x403)

   • Managed through:

     • coin::deny_list_v2_add (block addresses)
     • coin::deny_list_v2_remove (unblock addresses)

3. Global Pause:

   • Activated when allow_global_pause=true

   • Functions:

     • coin::deny_list_v2_enable_global_pause
     • coin::deny_list_v2_disable_global_pause

Metadata Objects

SDK Implementation Examples

TypeScript (Deny List Management)

const tx = new Transaction();
tx.moveCall({
    target: `0x2::coin::deny_list_v2_add`,
    arguments: [
        tx.object('0x403'),
        tx.object('<DenyCapV2_ID>'),
        tx.pure.address('<TARGET_ADDRESS>')
    ],
    typeArguments: ['<COIN_TYPE>']
});

Rust (Global Pause)

#[allow(unused_mut_parameter)]
public fun deny_list_v2_enable_global_pause(
    deny_list: &mut DenyList,
    deny_cap: &mut DenyCapV2,
    ctx: &mut TxContext
) {
    assert!(deny_cap.allow_global_pause, EGlobalPauseNotAllowed);
    let ty = type_name::get_with_original_ids().into_string().into_bytes();
    deny_list.v2_enable_global_pause(DENY_LIST_COIN_INDEX, ty, ctx)
}

Query Functions for Coin Data

Metadata Accessors

Supply Monitoring

• coin::supply(): Returns current circulating amount

FAQ: Coin Standard on Sui

Q: Can regular coins be converted to regulated coins?
A: No - regulation features must be implemented during initial creation via create_regulated_currency_v2.

Q: How quickly do deny list changes take effect?
A: Transaction blocking is immediate; receiving blocks apply at next epoch (~24 hours).

Q: Is metadata modifiable after creation?
A: Only for regular coins if not frozen. Regulated coin metadata is permanently frozen.

Q: What happens to coins during global pause?
A: All transaction inputs are blocked immediately. Receiving blocks activate next epoch.

Q: Can multiple addresses control deny lists?
A: Only the current DenyCapV2 bearer can modify the list - capability ownership is exclusive.

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Additional Resources

• Sui Tokenomics Documentation
• Closed-Loop Token Standard
• Rustdoc: coin module
• Rustdoc: token module