Cryptography
Linked Data Proofs
Also known as: LD Proofs, Data Integrity Proofs
A family of W3C proof formats that embed a cryptographic signature directly inside a JSON-LD document, rather than wrapping it externally.
Linked Data Proofs (LD Proofs) are proofs that live inside the signed document itself. A proof object declares a type (the signature suite), proofPurpose, verificationMethod, created timestamp, and a proofValue. The proof references the document but is a regular field of the document — verification involves canonicalizing the document (minus the proof field), hashing, and checking the signature against the referenced key.
The W3C VC Data Integrity specification formalizes the LD Proof model. Many proof suites exist: Ed25519Signature2020, DataIntegrityProof, EcdsaSecp256k1Signature2019, and Blockcerts-specific MerkleProof2019.
LearnCoin uses MerkleProof2019 — a Blockcerts-specific LD Proof suite that adds a Merkle path plus blockchain anchor to an underlying ECDSA signature. Because the proof is an in-document structure, credentials are self-contained: no separate detached JWS file, no external metadata. Everything needed to verify lives in one JSON-LD object.
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