📘 NEAR ProofType Smart Contract

This smart contract allows the registration of verifiable credential attestations on the NEAR blockchain. It is used as part of a decentralized identity (DID) and verifiable credentials (VC) flow, providing on-chain traceability of the issuer, subject, and the referenced content via a cid.

---

🚀 Functionality

✅ issue_credential

Registers a credential issued in the contract. Can only be called by the authorized issuer (signer in the app).

• Parameters:

  {
    "subject_did": "did:near:usuario.testnet",
    "cid": "bafybeigdyrzi...",
    "expires_at": null
  }

• cid definition: The cid represents the SHA-256 hash (Base64-encoded) of the verifiable credential JSON. It is used as a unique identifier for the credential on-chain.

• Requirements:

  • The cid must not have been previously issued for that subject_did.
  • The signer of the transaction will be recorded as the issuer.

• Recommended Gas: 30 TGas (30000000000000)

---

🔍 is_valid

Checks if a credential (subject_did, cid) has been issued and has not expired.

• Parameters:

  {
    "subject_did": "did:near:usuario.testnet",
    "cid": "bafybeigdyrzi..."
  }

• Returns: true | false

---

🧪 Usage Examples

Using near-cli

near call neardtiprooftype.testnet issue_credential \
  '{"subject_did": "did:near:usuario.testnet", "cid": "bafybeigdyrzi...", "expires_at": null}' \
  --accountId issuer.testnet --gas 30000000000000

near view neardtiprooftype.testnet is_valid \
  '{"subject_did": "did:near:usuario.testnet", "cid": "bafybeigdyrzi..."}'

---

🛠 SDK Integration

This contract integrates with the ProofTypeNear class:

const proof = await proofType.generateProof(vcPayload, { wallet, cid });
const valid = await proofType.verifyProof(proof); // true or false

Where vcPayload includes issuer, credentialSubject.id, and other VC fields.

---

🔐 Security

• Each subject_did + cid pair can only be issued once.
• Overwriting an existing record is not allowed.
• The issuer is tied to the signer of the transaction.

---

🧾 Specifications

• Network: testnet
• Contract: neardtiprooftype.testnet
• Language: Rust (near-sdk)
• Storage: Optimized by DID and list of CIDs
• License: MIT

---

📦 Compile & Deploy

cargo build --target wasm32-unknown-unknown --release
near deploy --wasmFile target/wasm32-unknown-unknown/release/prooftype.wasm --accountId neardtiprooftype.testnet

---

🧩 Relationship with DID Registry

This contract complements the Near DID Registry, which resolves DID documents. The ProofType acts as the attestation capability.