[Q²C]

Fraud-resistant Alternative to Traditional Birth Certificates

• zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge): These are compact proofs that require minimal computational overhead for verification, making them ideal for blockchain applications. They use elliptic curve cryptography and polynomial commitments to achieve succinctness and non-interactivity. For example, a zk-SNARK could prove “this individual was born before January 1, 2025” without disclosing the exact birth date.
• zk-STARKs (Zero-Knowledge Scalable Transparent Argument of Knowledge): An evolution of zk-SNARKs, zk-STARKs eliminate the need for a trusted setup (a potential security risk in SNARKs) and use hash-based cryptography, offering greater scalability and quantum resistance. They are computationally heavier but align with long-term security goals.

1. Proof Generation: At birth registration, a smart contract generates a ZKP alongside the hash of the birth record. For instance, the hospital computes a zk-SNARK proving attributes like “the birth occurred in 2025” or “the individual’s biometric hash matches the registered value.”
2. Storage: The ZKP is stored on-chain or linked via a Merkle tree root, while the full birth data remains encrypted off-chain (e.g., on IPFS).
3. Verification: A verifier (e.g., a government agency) submits a query to the smart contract, which validates the ZKP without accessing the underlying data. The process takes milliseconds and requires no direct interaction with the individual.

• Privacy: Sensitive details are never exposed, reducing risks of identity theft.
• Efficiency: Verification is fast and scalable, critical for widespread adoption.
• Flexibility: ZKPs can prove composite claims (e.g., “born in the EU and over 18”) tailored to specific use cases.

• Computational Overhead: Generating ZKPs requires significant resources. Pre-computation at registration and hardware acceleration (e.g., GPUs or ASICs) mitigate this.
• Complexity: Developers must integrate ZKP libraries (e.g., circom, snarkjs). Open-source standardization efforts, like those from the Ethereum Foundation, simplify adoption.
• Quantum Threats: While zk-SNARKs rely on elliptic curves (potentially vulnerable to quantum computing), zk-STARKs offer a quantum-resistant alternative for future-proofing.

• Legal Documents: Prove a contract was signed before a deadline without revealing its contents.
• Art and Music: Verify an artwork’s creation date or an artist’s authorship without disclosing proprietary details.

• Structure: A DID is a unique URI, e.g., did:ethr:0x123abc…, comprising a method identifier (ethr for Ethereum) and a blockchain-specific identifier (an address or public key).
• DID Document: Associated with each DID is a JSON-LD document stored on-chain or off-chain (e.g., IPFS), containing public keys, authentication methods, and service endpoints. For example:
  json

  {
    "@context": "https://www.w3.org/ns/did/v1",
    "id": "did:ethr:0x123abc...",
    "publicKey": [
      {
        "id": "#key-1",
        "type": "Secp256k1VerificationKey2018",
        "publicKeyHex": "0x..."
      }
    ],
    "authentication": ["#key-1"]
  }

• Resolution: DIDs are resolved via blockchain queries, mapping the identifier to its DID document.

1. Issuance: At birth, a smart contract generates a DID for the newborn, linking it to the hashed birth record. The DID is controlled by a public-private key pair, initially managed by parents or guardians (via a multi-signature wallet) until the child assumes control.
2. Key Management: The private key is stored securely (e.g., in a hardware wallet or encrypted mobile app). Recovery mechanisms, such as social recovery (delegating key fragments to trusted contacts), ensure access if the key is lost.
3. Updates: The DID document can be updated (e.g., adding new public keys) by the controller, with all changes logged immutably on the blockchain.
4. Interoperability: The DID integrates with Verifiable Credentials (VCs), a W3C standard for digitally signed claims. For example, a VC issued by a hospital might assert “born on January 15, 2025,” signed with the hospital’s private key and verifiable via its DID.

• Self-Sovereignty: Individuals control their identity data, deciding what to share and with whom.
• Interoperability: DIDs work across blockchains and jurisdictions, supporting global adoption.
• Security: Private keys, not centralized databases, authenticate identity, reducing breach risks.

• User Experience: Managing private keys is complex for non-technical users. Wallet apps with biometric authentication (e.g., uPort, Keybase) simplify this.
• Adoption: Institutions must recognize DIDs legally. Pilot projects in the EU (eIDAS integration) and UN initiatives (digital identity for refugees) pave the way.
• Revocation: If a DID’s private key is compromised, revocation mechanisms (e.g., updating the DID document to nullify old keys) must be robust.

• Legal Documents: A DID ties a contract to its signatories, enabling secure, verifiable updates or transfers.
• Art and Music: Artists register DIDs to claim ownership, linking them to NFTs or digital signatures on creative works, ensuring provenance.

• Privacy + Control: ZKPs prove specific attributes (e.g., age eligibility) without revealing full records, while DIDs ensure the individual retains ownership of the underlying identity.
• Scalability: ZKPs reduce on-chain data exposure, and DIDs offload detailed identity management to decentralized storage, optimizing blockchain efficiency.
• Use Case Example: A job applicant uses their DID to present a Verifiable Credential asserting “over 21,” backed by a ZKP proving the claim against their birth record, all without disclosing their exact birth date.