The rapid growth of digital services has increased the demand for identity systems that provide strong authentication while minimizing unnecessary disclosure of personal information. Conventional identity management architectures generally depend on centralized identity providers and frequently require users to disclose complete identity attributes even when a service requires only a limited assertion. Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs) provide an alternative model in which identity holders can manage cryptographically verifiable credentials independently of a centralized identity provider. However, the privacy guarantees of decentralized identity systems depend substantially on the cryptographic proof mechanism used during credential presentation.

Zero-Knowledge Proofs (ZKPs) enable a prover to demonstrate knowledge of a secret or the validity of a statement without revealing the underlying secret. Different ZKP and selective-disclosure mechanisms exhibit significantly different characteristics with respect to proof size, generation time, verification time, communication overhead, computational requirements, privacy guarantees, interoperability, and implementation complexity. Consequently, selecting a single proof mechanism for every decentralized identity scenario can result in unnecessary computational cost or inadequate privacy protection.

This paper proposes an Adaptive ZKP Selection Framework (AZSF) for privacy-preserving decentralized identity using DIDs and Verifiable Credentials. The framework dynamically selects an appropriate proof mechanism according to the privacy sensitivity of requested attributes, disclosure requirements, verifier trust conditions, computational resources, proof-generation latency, communication constraints, interoperability requirements, and unlinkability requirements. The proposed architecture introduces a policy-driven decision layer between the credential wallet and proof-generation subsystem. It evaluates candidate mechanisms including selective-disclosure signatures, BBS-based proofs, SD-JWT-based selective disclosure, and general-purpose succinct zero-knowledge proof systems such as zk-SNARK/PLONK-style approaches.

A formal multi-criteria decision model is developed to represent the selection process. The framework defines privacy, performance, communication, interoperability, and deployment criteria and computes an adaptive suitability score for each candidate proof mechanism. A threat model covering credential theft, replay, correlation, malicious verifiers, issuer compromise, metadata leakage, and proof substitution is presented. The paper further proposes an experimental methodology for evaluating proof generation time, verification time, proof size, communication overhead, privacy leakage, unlinkability, and resource consumption. The proposed framework provides a systematic foundation for choosing cryptographic proof mechanisms according to application requirements instead of adopting a one-size-fits-all approach.

Index Terms— Decentralized Identity, Decentralized Identifiers, Verifiable Credentials, Zero-Knowledge Proofs, Privacy-Preserving Identity, Selective Disclosure, BBS Signatures, SD-JWT, Self-Sovereign Identity, Privacy Engineering, Adaptive Cryptography.