Guides

Mint NFTs (CIP-68)

What is CIP-68?#

Cardano Improvement Proposal 68 (CIP-68) is a metadata standard that revolutionized how NFT metadata is managed on Cardano. It enabled truly updatable metadata after minting through a dual-token architecture, perfect for dynamic NFTs like game items, evolving collectibles, or interactive art.

Why CIP-68 Was Created#

CIP-25 Limitations:

  • Metadata inaccessible to smart contracts (stored in transaction metadata).
  • Complex and high cost metadata updates requiring mint/burn cycles with double-mint periods.
  • Metadata resolution requires scanning blockchain history to find the "last minted transaction" for each token.
  • Permanent immutability once policy is time-locked.

CIP-68 Solution: A dual-token architecture separating metadata storage from ownership, enabling seamless updates, smart contract integration, and enhanced security through datum-based metadata storage. Unlike CIP-25, metadata updates remain possible even after the minting policy is time-locked, as updates are controlled by the reference token's spending script rather than the minting policy.

CIP-68 Trade-offs:

  • Higher initial minting costs (requires creating two tokens instead of one)
  • Increased complexity managing dual-token architecture, creating additional UTxO overhead for reference token storage.

How It Works#

CIP-68 uses an innovative dual-token system where each NFT consists of two linked tokens:

  • Reference Token (Label 100): Stores the updatable metadata at a script address or Admin wallet
  • User Token (Label 222): Resides in the user's wallet and inherits metadata from the reference token

This separation allows metadata updates without affecting user ownership or requiring token transfers.

Validation Approaches: Native Scripts vs. Smart Contracts#

CIP-68's updatable metadata is managed by a Reference Token, which can be secured in two ways:

  1. Metadata-Manager Wallet with a Native Script: This approach uses a standard wallet and a native script to control the Reference Token. It's straightforward and low-cost, making it ideal for projects that don't need complex on-chain logic. The trade-off is that it relies on trusting the wallet owner to manage metadata updates and token supply correctly.

  2. Smart Contract (Plutus/Aiken): This method uses a full smart contract to govern the Reference Token. While someone still needs to trigger updates, the smart contract validates critical aspects like supply limits and reference token to user token ratios on-chain, requiring less trust than the wallet approach. It enables complex rules for metadata updates, supply caps, and other on-chain logic, but is more complex and expensive to develop and interact with.

The choice between them depends on your project's need for trustless validation versus simplicity and cost-effectiveness. If you need custom smart contract development, or are not sure which option to choose, we recommend reaching out at hello@ada-anvil.io.

Prerequisites#

Before you start, make sure you have:

Choose Your Approach#

CIP-68 offers two main validation approaches for securing reference tokens:

Choose your approach based on your specific needs:

Criteria Native Scripts Smart Contracts
Validation Logic Customization Simple signature + timelock validation Complex programmable business rules
Metadata Updates Manual wallet-based updates Automated rule-based validation
Development Complexity Low - JSON configuration High - Aiken Development
Cardano Transaction Costs Lower Higher (~2x ADA)
Use Cases Simple collections, personal projects Gaming, DeFi, enterprise applications

All Guides#

Getting Started#

Native Script MintingA Deno-based script for minting CIP-68 assets on the Cardano blockchain using the Anvil API. This guide provides a complete example for building, signing, and submitting a transaction to mint a CIP-68 NFT using the Metadata-Manager Wallet approach.

Smart Contract Guides#

Mint LogicUnderstanding the smart contract - How to mint NFTs on Cardano (in accordance to CIP-68 standard) using Aiken smart contracts. Cardano interactions powered by Anvil API

Update LogicUnderstanding the smart contract - How to update CIP-68 NFT metadata on Cardano using Aiken spend validators. Deep dive into user vs admin update paths, fee mechanisms, and validation logic.

Mint ExampleThis guide provides a complete Deno implementation for minting CIP-68 NFTs using parameterized smart contracts with the Anvil API.

Admin Update ExampleThis guide provides a complete Deno implementation for updating CIP-68 NFT metadata using spend validators with parameterized smart contracts and the Anvil API.

User Update ExampleThis guide provides a complete Deno implementation for user-driven CIP-68 NFT metadata updates using spend validators, fee payments, and token ownership verification with the Anvil API.

References & Further Reading#

Official CIP Specifications#