Contract bound verifiable credentials for replay resistant container image provenance in Kubernetes

Abstract Container image distribution in cloud-native supply chains is exposed to replay attacks, in which an attacker reuses a valid signature or credential in a context for which it was never issued. This paper presents a contract-bound decentralized identity framework for container image authentication in Kubernetes. Each image is described by a Verifiable Credential that carries two anchors inside the signed payload: the manifest digest of the image and a contract-binding context, defined as the pair consisting of a chain identifier and a smart-contract address that together name the trust domain of the verifier. A validating admission webhook admits an image only when the digest matches, the context declared by the credential equals the context configured for the cluster, the issuer signature verifies against a decentralized identifier document bound to an on-chain record, and the credential is recorded and not revoked on chain. A prototype built on Arbitrum Sepolia, IPFS, and a Kubernetes admission webhook rejected forged, replayed, and revoked credentials in every controlled trial. Mean admission latency was 0.91 s on the cached path and 1.78 s on the fresh path, and revocation reached verifiers within 1.9 s at the 95th percentile when driven by contract events. These guarantees are conditional rather than absolute. They hold while the issuer keys, the deployed contract, and the verifier configuration remain uncompromised, and the design fails closed, so an outage of the blockchain endpoint or of content retrieval denies admission instead of weakening verification. Within those limits, contract-bound credentials give Kubernetes a portable and revocable provenance layer that needs neither a central certificate authority nor registry-specific policy.