[TEP-85] Enhancing Blockchain Functionality with Soul Bound Tokens: A Comparative Analysis of the SBT Contract Interface

In the evolving landscape of blockchain technology, the introduction of Soul Bound Tokens (SBT) represents a significant milestone in the diversification of digital assets. Unlike traditional Non-Fungible Tokens (NFTs), SBTs are characterized by their non-transferability, introducing a novel approach to ownership and utility within blockchain ecosystems. This paper delves into the specifications, motivations, and potential implications of the SBT Contract, as outlined in the TEP proposal number 85, with a focus on its role in facilitating new forms of digital identity, ownership, and certification.

Comparative Analysis

Feature SBT Contract Traditional NFT Standard
Transferability Not transferable; designed to be soul bound to the owner. Transferable between parties.
Use Cases Certificates, roles/permissions, onchain ownership proofs. Art, collectibles, gaming items.
Ownership Proofs Supports onchain proofs of ownership with optional revocation by authority. Ownership proved by possession in wallet.
Revocation Optional revocation mechanism by an authority. Generally, no revocation mechanism.
Destruction Owners can destroy their SBT at any time. Dependent on contract specifics.
Interface Methods Implements NFT standard interface with rejection of transfer method. Includes unique methods like prove_ownership, request_owner, destroy, and revoke. Standard NFT interface without restrictions on transferability.

Motivation Behind the SBT Contract

The SBT contract interface is propelled by the need for a blockchain-based mechanism to represent immutable, non-transferable ownership and roles. It addresses the gap in digital ecosystems for tokens that symbolize personal achievements, memberships, or certifications, which should not be transferable to maintain their integrity and the authenticity of their representation.

Implementation and Technical Specifications

The technical backbone of the SBT contract is built upon the TON blockchain’s NFT standard interface, with critical modifications to ensure the tokens are soul bound. Key functionalities include:

  • Prove Ownership: Enables SBT owners to prove ownership to other contracts, enhancing interaction within the blockchain ecosystem without compromising the non-transferable nature of SBTs.
  • Request Owner: Allows querying of SBT ownership details by any party, facilitating verification and validation processes.
  • Destroy: Provides the option for an SBT owner to nullify their token, adding a layer of control and flexibility.
  • Revoke: An authority-specific function that enables the revocation of an SBT, introducing a dynamic aspect to the otherwise permanent nature of these tokens.

Practical Application and Guide

The practical utility of SBTs is vast, with applications ranging from academic certifications to membership validations and beyond. The guide outlines procedures for minting, proving ownership, and interacting with contracts in a way that leverages the unique attributes of SBTs, offering a blueprint for integrating soul-bound tokens into various blockchain-based applications.

Rationale, Alternatives, and Future Directions

The design of the SBT contract is a response to the need for a more nuanced form of digital asset that transcends the limitations of transferability. While other designs, such as ETH’s EIP-4973, have approached the concept of non-transferable tokens, the SBT contract introduces additional functionalities like onchain proofs and revocation that broaden its application spectrum. The decision against including equip/unequip mechanics, as seen in EIP-4973, stems from a focus on maintaining the integrity of what SBTs represent. Looking ahead, the SBT standard appears to be a comprehensive solution, though its evolution will likely continue in response to emerging use cases and technological advancements.


The SBT Contract Interface represents a forward-thinking addition to the blockchain technology space, offering a versatile framework for the creation and management of non-transferable tokens. By enabling the representation of immutable personal achievements and roles on the blockchain, SBTs pave the way for innovative applications that could transform how digital identity and ownership are conceptualized and verified within digital ecosystems.

The introduction of the Soul Bound Token (SBT) contract within the TON blockchain ecosystem, as outlined in the TEP 85, heralds a significant leap in the utility and applicability of non-transferable tokens. This comprehensive specification, crafted by a team of notable authors including Oleg Baranov, Narek Abovyan, Kirill Emelyanenko, and Oleg Andreev, aims to infuse the TON network with a type of token that is immutable in ownership yet versatile in its use cases, from social permissions and roles to attestation certificates.

Analytical Insight

The motivation behind the SBT is clear and well-founded. The need for tokens that can represent non-transferable assets or qualifications in a digital format is increasingly becoming apparent in various blockchain applications. By integrating features such as revocation by authority and onchain ownership proofs, the SBT standard not only ensures the integrity of such tokens but also provides a mechanism for their validation and potential invalidation, thus offering a dynamic layer of interaction not present in traditional NFTs.

Comparative Evaluation

Feature SBT (TON) ABT (Ethereum EIP-4973)
Transferability Non-transferable Non-transferable
Revocation Supported, by authority Not mentioned
Onchain Ownership Proof Supported Not explicitly mentioned
Destruction Holder can destroy Not specified
Equip/Unequip Mechanics Not supported Supported

This comparative analysis illuminates the SBT’s unique stance within the landscape of blockchain-based, soul-bound tokens. Particularly, its revocation feature and onchain ownership proof extend its utility beyond the Ethereum’s ABT proposal, potentially paving the way for a wider array of applications within the TON ecosystem.

Professional Inquiry

  1. Extension of Functionality: Given the static nature of the SBT as proposed, how might future iterations allow for dynamic interactions akin to the equip/unequip mechanics seen in Ethereum’s ABT, without compromising the soul-bound principle?

  2. Interoperability Concerns: With the SBT’s rigid non-transferability and potential for revocation, what measures are in place or proposed to ensure seamless interaction with other tokens and contracts within the TON ecosystem, especially in decentralized finance (DeFi) applications where fluidity of assets is crucial?

  3. Authority Revocation Mechanism: The specification allows for the revocation of SBTs by an authority. Could you elaborate on the safeguards or protocols established to prevent potential abuse of this power, ensuring that the revocation mechanism is used judiciously and transparently?

  4. SBT Destruction: The ability for a holder to destroy their SBT introduces interesting dynamics in terms of token lifecycle management. What implications does this have for the permanence of digital certifications or qualifications represented by SBTs, and how might this impact their credibility and long-term value?

  5. Future Developments: As the standard appears finalized, what considerations are being made towards evolving the SBT specification to accommodate emerging blockchain technologies or novel use cases that may require adjustments to the current framework?

The SBT initiative within the TON blockchain is a forward-thinking endeavor that addresses a tangible need for non-transferable tokens with verifiable ownership. As the blockchain space continues to evolve, the development and refinement of standards like the SBT will be critical in harnessing the full potential of blockchain technology for secure, transparent, and versatile digital assets.