BNB Attestation Service

• Name: BNB Attestation Service (BAS)
• URL: https://docs.bnbchain.org/showcase/identity/attestation/
• Category: attestation infrastructure / schema-and-resolver middleware / BNB identity primitive
• Tags: bnb-ecosystem
• Summary: BAS is BNB Chain’s schema-plus-resolver attestation rail. The useful part is the explicit policy split: schemas define shape, resolvers decide admission, and some records can live offchain in Greenfield. Real middleware, not an attestation anchor.
• What it does:
  • Lets users define arbitrary attestation schemas, including optional resolver contracts that add custom issuance logic
  • Supports both onchain attestations on BNB Chain and offchain attestations that can be stored or pinned in Greenfield
  • Treats schemas as reusable data definitions and resolvers as hook points for payment, eligibility, or other policy checks
  • Exposes attestation records with unique UIDs, decoded schema data, status, and reference relationships
  • Positions itself as general attestation middleware for identity, reputation, KYC, and related data-import use cases
  • Shows first-party examples around privacy-preserving KYC and developer reputation through projects such as zkPass and Aspecta ID
• Key claims:
  • The official BNB Chain docs describe BAS as a standard and infrastructure for arbitrary attestations, which is the clearest reason to treat it as reusable middleware rather than one application feature
  • BAS splits the system into schemas, attestations, and resolvers. That decomposition matters because structure, issuance, and policy are not bundled into one opaque object
  • The docs say anyone can define schemas and attach resolver logic, so issuer openness is not a fixed property of BAS itself; it depends on how each schema is configured
  • The attestation docs emphasize support for both onchain and offchain attestations, with Greenfield used for records that should not sit fully in public chain state
  • The reviewed materials leave BAS looking more policy-rich than attestation-station but less central than the stronger cross-ecosystem attestation rails
• Whitepaper: No standalone BAS whitepaper or litepaper surfaced in this pass. The strongest primary materials were the official BNB Chain and BAS docs plus the linked contract repository, collected in ../whitepapers/bnb-attestation-service-primary-sources-2026-05-11.md.
• Sources:
  • https://docs.bnbchain.org/showcase/identity/attestation/
  • https://doc.bascan.io/core_concept/schema
  • https://doc.bascan.io/core_concept/attestation
  • https://doc.bascan.io/core_concept/resolver
  • https://github.com/bnb-attestation-service/bas-contract

Internal linkages

• Best upward reads: ethereum-attestation-service and sign-protocol.

Practical control points

• Control sits in schema design, resolver logic, storage choice, and which BAS attestations downstream apps or indexers decide to trust.

• So the right cut is not onchain vs offchain in the abstract. It is who defines issuance policy and where the meaningful data custody actually lives.

• Last reviewed: 2026-06-04 UTC