Presentation Definition

A Presentation Definition is a standardized data structure, defined by the Decentralized Identity Foundation (DIF), that specifies the verifiable credentials a verifier requires from a holder. It acts as a formal request, detailing the types of credentials, the specific claims within them, and the cryptographic proofs needed. This definition is typically expressed in JSON or JSON-LD and is the cornerstone of the W3C Verifiable Credentials Data Model and protocols like OpenID for Verifiable Presentations (OID4VP) and Presentation Exchange.

The core components of a Presentation Definition include input descriptors, which define the required credential schema (e.g., a driver's license), and constraints, which specify the exact claims (e.g., dateOfBirth) and potentially the issuers trusted by the verifier. It may also require specific proof types, such as a JSON Web Signature (JWS) or Data Integrity Proof, to ensure the credential's authenticity and integrity. This allows a verifier to request, for example, "a government-issued ID from a trusted issuer proving the holder is over 21" in an unambiguous, machine-processable format.

In the credential exchange flow, the verifier sends the Presentation Definition to the holder's wallet. The wallet software then evaluates its stored credentials to find a match that satisfies all constraints. If a match is found, the wallet constructs a Verifiable Presentation—a wrapper containing the selected credentials and proofs—which is then submitted back to the verifier. This process enables selective, privacy-preserving disclosure, as the holder only shares the minimum necessary data required by the definition.

Presentation Definitions are fundamental to implementing zero-knowledge proofs and data minimization principles in digital identity. For instance, a definition can be crafted to require a cryptographic proof of age (e.g., over 18) without revealing the exact birth date. By standardizing the request format, they ensure interoperability between different wallet and verifier implementations, forming the technical basis for trusted data exchanges across web2 and web3 ecosystems, from KYC checks to decentralized access control.

A Presentation Definition is a structured data object, typically formatted in JSON, that specifies the verifiable credentials a verifier requires from a holder. It acts as a formal request, detailing the specific credential types, the claims (or attributes) needed from them, and the cryptographic proofs required for verification. This definition is governed by standards like the W3C Verifiable Credentials Data Model and the Decentralized Identity Foundation's Presentation Exchange specification, ensuring systems from different issuers can interoperate.

The core function of a Presentation Definition is to enable selective disclosure. Instead of presenting an entire credential, a holder can use cryptographic techniques like BBS+ signatures or zero-knowledge proofs to prove they possess credentials that satisfy the definition's constraints without revealing extraneous information. The definition can mandate specific credential schemas, require certain issuer DIDs, and set policies for credential status (e.g., not revoked). This allows for privacy-preserving, minimal-data exchanges.

In a typical flow, a verifier sends its Presentation Definition to a holder's wallet. The wallet software evaluates the holder's stored credentials to find a match. If suitable credentials exist, the wallet constructs a Verifiable Presentation—a wrapper containing the disclosed proofs—that conforms to the definition's rules. This presentation is then returned to the verifier for validation. This mechanism is fundamental to user-centric identity, giving individuals control over what personal data they share in any given transaction.

In the Verifiable Credentials (VC) data model, a Presentation Definition is a standardized format, often expressed in JSON, that a verifier (the entity requesting proof) sends to a holder (the entity presenting credentials). It specifies the precise set of credentials, claims, and constraints required for a successful verification. This includes the types of credentials (e.g., a driver's license), the specific claims needed from within them (e.g., dateOfBirth), and any additional proof requirements like cryptographic signatures or Zero-Knowledge Proof (ZKP) predicates. This machine-readable format enables automated, interoperable exchanges between different software systems.

The structure of a Presentation Definition is governed by the Presentation Exchange (PE) specification, which provides a common language for credential negotiation. Key components include input_descriptors, which define each required credential, and constraint objects that detail the allowed issuers, schema types, and field-level rules (e.g., "minimum": 21 for an age check). This allows a verifier to request complex, conditional logic—such as "Proof of age over 21 or a government-issued membership credential"—without needing to understand the holder's specific credential format in advance.

For the holder, a Wallet or agent application processes the Presentation Definition to determine if it can be satisfied with the credentials in its possession. The holder then constructs a Verifiable Presentation—a packaged response containing the requested credentials and proofs—that conforms to the definition's rules. This decoupled request-response pattern is fundamental to preserving user-centric identity and selective disclosure, as the holder maintains control over their credentials and only shares what is explicitly required.