> For the complete documentation index, see [llms.txt](https://whitepaper.interlinklabs.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://whitepaper.interlinklabs.ai/interlink-network/interlink-sdk/human-auth-sdk.md).

# Human Auth SDK

<figure><img src="/files/d5HVyDpISX0hKsY5V6rA" alt=""><figcaption><p>InterLink SDK</p></figcaption></figure>

Unlike typical SSO systems tied to centralized identity providers (e.g., Google or Facebook), InterLink SSO uses on-chain, biometric-anchored identity, ensuring each login is performed by a unique, verified human.

<figure><img src="/files/jzXfYkW10ea8hEQPztrn" alt=""><figcaption><p>Difference between InterLink SSO and centralized identity providers</p></figcaption></figure>

**Components**

* InterLink SDK (frontend): injected into web/mobile client
* InterLink App (mobile): handles secure biometric confirmation
* Verifier Node: decentralized endpoint (on-chain or light node) that verifies signed payloads
* Credential Resolver (optional): fetches and validates user-bound credentials (e.g., passport, age proof)

**Core Capabilities**

* Biometric-based login (liveness, uniqueness enforced)
* JWT or ZK-style signed assertions of human = true, age > 18, or has\_passport = true
* InterChain identity binding, InterLink ID can be mapped to wallets across EVM, Solana, Cosmos, etc.
* Offline-capable, signatures cached locally; used for dApps with intermittent connectivity
* No PII transmission, biometric and credential data remain on-device, never exposed

**Integration Highlights**

* Web2-ready: SDK available as JavaScript module, RESTful fallback
* Web3-native: Pluggable with WalletConnect, Ethers.js, wagmi
* Mobile-ready: React Native and Flutter bridges supported
* Developer Options: Verify-only (read a Human)
* Challenge flow (return signed payload for replay protection)
* Credential gate logic (use cases: age, residency, document check)

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