Introducing zkSBTs, zkNFTs, and NPO

Manta Network introduces support for nonfungible assets including NFTs and SBTs, which can be launched through its new NPO platform.

Manta Network
6 min readMar 20

The MantaPay protocol originally supports fungible cryptoassets (i.e., cryptocurrencies). To bring privacy to web3, more decentralized asset classes need to be supported, namely, NFTs and SBTs. Manta Network is excited to announce its work in this area, bringing privacy-preservation support to non-fungible cryptoassets including SBTs and NFTs using Manta Network’s ZK technology. These assets can be minted through its upcoming platform, the NFT Private Offering (NPO).

Manta Network’s NPO platform is set to revolutionize how users generate and mint zkNFTs/zkSBTs. NPO is an NFT/SBT launchpad that leverages the Manta Network’s zkAddress tooling and the MantaPay ZK circuit to privately mint NFTs/SBTs on zkAddress while using public tokens to pay minting fees. It is a unique product that allows any projects or users on Manta to launch zkNFTs/zkSBTs privately without any technical or cryptographic experience.

In this article, we will provide a comprehensive overview of NPO and zkNFT/zkSBT, including their respective functionalities and benefits. The ZK technology behind zkNFTs/zkSBTs enables a frictionless NFT minting process with verifiability on-chain or off-chain without the necessity of disclosing public addresses or linked assets.

Manta’s zkNFTs/zkSBTs enable developers to build without in-depth knowledge of cryptography or ZKP for web3 or web2 applications; the plug-and-play connection with zkNFTs/zkSBTs enables applications to be quickly developed on mobile, opening up new opportunities for developers to create zkNFT/zkSBT projects including mobile applications, DApps, and projects based on NPO.

What is the NFT Private Offering (NPO)

NPO is a decentralized zkNFT/zkSBT Launchpad that combines zero-knowledge technology with NFTs, enabling private minting and verification. With NPO, users can easily mint NFTs and SBTs while maintaining the privacy of their crypto assets. By leveraging Manta Network’s zkAddress tooling, NPO enables users to mint NFT/SBT on their zkAddress while using public addresses’ tokens to pay for the minting fee.

Manta’s NPO platform is a game-changer in web3. It enables the launch of zkSBTs, which are private and user-friendly SBTs. With NPO, Manta Network continues leading in developing privacy-focused blockchain technologies. Leveraging Manta’s MantaPay ZK circuit, NPO provides a secure and decentralized way for users to mint and verify NFTs and SBTs, ensuring that all transactions are conducted with the utmost privacy and confidentiality.

What is an SBT?

Soulbound tokens, or SBTs, are digital identity tokens representing a person or entity’s characteristics, features, traits, and achievements. Built on blockchain technology, it takes NFTs applications to the next level. Unlike NFTs, SBTs cannot be transferred or traded between different owners.

Vitalik Buterin posted an article about Soulbound on Jan 26, 2022. In his blog post, Vitalik Buterin discusses the challenges of adding privacy to soulbound items, which cannot be moved to a new account or smart contract like transferable assets. He notes that as proof of humanity becomes more widely adopted, privacy becomes increasingly important, as all on-chain activity could be directly linked to a person’s identity.

To address this challenge, Buterin suggests several technical options, including storing the item at an address that is a hash of an index, the recipient address, and a secret belonging to the recipient. This would allow for privacy, as only those with the secret could see which items belong to the recipient. Other options include publishing a hash of a bunch of items and providing each recipient with their Merkle branch, using ZK-SNARKs to prove ownership of an item, and using ZK-SNARKs to facilitate on-chain transfers while maintaining privacy.

Buterin emphasizes that privacy is an essential part of making this kind of ecosystem work well, particularly in cases where users may not want to reveal everything they own. He suggests that incorporating privacy into the design can help avoid bad outcomes and increase the chances of creating a successful system.

What Is a zkSBT?

zkSBT (Zero-Knowledge Soulbond Token) is an enhanced Soulbond Token that uses ZKPs to provide security and privacy features compared to traditional SBTs. Similar to SBTs, zkSBTs are easy to mint and use for verification purposes, offering the same user experience but with added privacy. As part of Manta Network’s mission to become the privacy hub for web3, zkSBTs are designed to provide a chain-agnostic experience. In other words, users can launch the tokens on other chains including Ethereum, BNB Chain, Polygon, and more; meanwhile, the privacy credentials through zkSBTs are maintained on Manta Network’s chain, which can be verified through Proof Keys without the need for any wallet disclosures.

The use of ZKPs allows for secure and private minting without revealing any additional information beyond the validity of the transaction itself. This means that users can mint zkSBTs while preserving ownership privacy, which allows for the users to maintain segregation between their zkAddress and all other assets including the zkSBT, that belong to said zkAddress.

One essential technology developed by Manta Network is the zkAddress. The zkAddress is a reusable, independent, and auditable address for your private assets in Manta (more info about the zkAddress). A zkSBT is bound to a single zkAddress; i.e., one zkAddress can have multiple zkSBTs, but one zkSBT can only be minted on one zkAddress. zkSBTs are not transferable. The zkSBT’s metadata is as flexible as any SBT and can include data such as a PFP, a normal photo, AI photos, social graph, web2 handles (Twitter, Instagram), etc.

zkSBTs cannot be linked to identities through a public blockchain explorer. Additionally, each zkSBT has another key piece of Manta-developed technology: Proof Keys. The Proof Key is a protocol that allows users to verify their identity on-chain without the necessity of a wallet. The Proof Key makes it easy for mobile applications to check the identity/ownership of a zkSBT. To prove their identity, they would need to show the zkSBT has been minted to their zkAddress and show they have ownership of that zkAddress (More info about the Proof Key).

Some verification use cases of zkSBT:

  • Profile pictures (through the metadata) in a privacy-preserving manner, including photos or AI-generated images;
  • On-chain transactions or crypto assets without the need to disclose address information;
  • In-game items that users have purchased on-chain;
  • Decentralized social graph information that does not link user identity or contain linkages between social identities.

It should be noted that by using Proof Keys, zkSBTs can be verified through mobile applications without the direct need for wallet signatures or verification, making it easy for mobile developers to integrate Manta’s zkSBT directly into their applications.

Deploying zkSBTs: No Cryptographer Needed

Deploying a Manta zkSBT does not require deep technical knowledge or understanding of cryptography. Manta Network has abstracted away the complexity and delivered an easy experience for any developer to understand and use zkSBTs. To launch a zkSBT, the developer can utilize the SBT SDK, an extension of the MantaPay SDK that includes custom logic such as pre-charge steps for reserving SBT asset IDs and enabling users to mint SBTs by providing metadata. This metadata has a 300-character limit and can contain an image URL or any other data. Developers should use the SBT SDK to enable user-minting of zkSBTs because the Signer is required to generate the TransferPost that contains the ZKP.

About Manta Network

Manta Network is the zk layer 1 blockchain with the fastest prover speed and most decentralized trusted setup that brings programmable privacy to web3. Its suite of core products and technologies, including zkNFTs and MantaPay, offers user-friendly access to powerful ZK-enabled use cases.

The project is created by a team of experienced founders from prestigious institutions, including Harvard, MIT, and Algorand. The team began its research on Zero Knowledge Proof in 2019 during a cross-border payment research project under the MIT Digital Currency Initiative with the Monetary Authority of Singapore. Manta Network has received investments from many of the top web3 investment funds, including Binance Labs and Polychain Capital. It has grown through participation in the best web3 accelerators, including Alliance DAO and Berkeley Blockchain Xcelerator. Manta Network is poised to bring the next generation of web3 users and usher in a new chapter of privacy-focused web3 applications.

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