Why BBS+ Enables a New Era of Selective Disclosure

Traditional zero-knowledge proofs (ZKPs) for credentials are computationally heavy and require specialized circuits for each new attribute check. This creates a scalability bottleneck and vendor lock-in, making selective disclosure impractical for mainstream dApps.

• High Overhead: Proving a single attribute often requires proving the entire credential structure.
• Circuit Bloat: Each new proof statement requires a new, audited circuit, slowing development.

BBS+ is a randomizable signature scheme where a single credential can generate countless zero-knowledge proofs for any subset of its attributes, without interacting with the original issuer.

• Attribute-Wise Randomization: Cryptographically unlink each proof to the master credential.
• One Credential, Infinite Proofs: Supports any future predicate without new circuits.
• Post-Quantum Secure: Based on elliptic curve pairings, resistant to quantum attacks.

The W3C VC Data Model provides the standardized container (JSON-LD), while BBS+ provides the cryptographic layer. This combo, championed by MATTR and Sphereon, creates portable, vendor-agnostic credentials.

• Interoperability: Works across chains and off-chain systems.
• Selective Disclosure: Prove you're over 21 without revealing your birthdate or name.
• Holder-in-the-Loop: User cryptographically controls all disclosures, enabling true self-sovereign identity.

Current SBTs are non-private and non-composable. BBS+ enables Private, Provable SBTs where the on-chain token is a commitment, and the holder stores the private credential. Think Aztec Protocol for identity.

• Private Attestations: Prove SBT ownership without exposing wallet address.
• Cross-Chain Reputation: Use a credential from Ethereum to access a DeFi pool on Arbitrum with a privacy-preserving KYC proof.
• Composable ZK Proofs: Feed BBS+ proofs into other ZK circuits (e.g., zkSNARKs in zkSync).

Replace opaque DAO membership NFTs or KYC gateways with cryptographic proofs of eligibility. Projects like Orange Protocol and Verax are building registries for this.

• DeFi: Prove accredited investor status or country eligibility without a middleman.
• DAO Governance: Prove you hold a specific NFT from a collection (e.g., BAYC) without revealing which one.
• Gaming: Prove achievement completion across games without a centralized backend.

BBS+ shifts the computational burden off-chain. The on-chain verifier is a single, constant-time pairing check, making it ~100x cheaper than generic ZK verification. This enables high-frequency, low-value attestations.

• Fixed Gas Cost: Verification cost is constant, regardless of how many attributes are disclosed.
• Batch Verification: Verify thousands of credential proofs in a single transaction, akin to ERC-4337 bundling.
• L2 Native: Ideal for Starknet and zkEVM rollups where compute is cheap but data is expensive.

BBS+ is the core signature scheme for W3C's Selective Disclosure standard. It allows a single credential to be reused for multiple proofs without correlation.

• Key Benefit: Enables privacy-preserving KYC where users prove they are over 18 without revealing their birthdate or name.
• Key Benefit: Powers reusable identity proofs for DeFi, replacing one-time attestations that leak user graphs.

This project uses BBS+ to create ZK proofs from India's national ID. Users prove citizenship or uniqueness without exposing their Aadhaar number.

• Key Benefit: Enables sybil-resistant governance and airdrops for ~1.3B people without doxxing them.
• Key Benefit: The credential is bound to a user's wallet, preventing sale or transfer, which plagues NFT-based proof-of-personhood.

Sismo uses BBS+ for its ZK Badges, which are non-transferable attestations derived from private user data (e.g., GitHub, Twitter).

• Key Benefit: Users aggregate reputation across platforms into a single private profile for on-chain access.
• Key Benefit: Protocols can gate access based on provable traits (e.g., "Top 100 Gitcoin donor") without seeing a user's full history.

Polygon ID's infrastructure uses BBS+ for privacy-by-default credentials. Enterprises issue verifiable claims that users can selectively disclose.

• Key Benefit: Supports large-scale enterprise adoption where data minimization is a legal requirement (GDPR).
• Key Benefit: Enables private credential revocation, a critical feature for real-world compliance that naive ZK schemes lack.

Hyper Oracle uses BBS+ to create verifiable off-chain computations. Provers can sign state attestations that allow for selective disclosure of the computation result.

• Key Benefit: Enables private verifiable data feeds (oracles) where the data source or specific values can remain hidden.
• Key Benefit: Allows ZK-authenticated APIs where a user proves a property about API data without the verifier querying the API directly.

Projects are replacing heavy zk-SNARK circuits with BBS+ for credential proofs. The math is simpler and cheaper for the core function of hiding attributes.

• Key Benefit: ~100x cheaper proof generation than a generic zk-SNARK circuit for the same selective disclosure claim.
• Key Benefit: Native multi-message signing means the cryptographic primitive aligns perfectly with a credential's structure, reducing complexity.