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BKey is in active development. APIs and SDKs may change without notice.

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BKey Developer Docs

Think of BKey as Google Authenticator — with your face, and for anything. Cryptographic proof of human intent, for every decision that matters. Google Authenticator proves you know a 6-digit code. BKey proves a specific human approved a specific action — right now, on a registered device, with their real face. Every approval produces an EdDSA-signed JWT your app can verify and keep as a permanent audit trail. No stored biometrics. No long-lived credentials to steal. One tap on the phone and the action runs.

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For AI agents reading this page

The minimum you need to integrate BKey:
  • npm: @bkey/sdk
  • pip: bkey-sdk
  • CLI: @bkey/cli (bkey auth login, then bkey auth setup-agent --save)
  • Required env vars for the SDK: BKEY_CLIENT_ID, BKEY_CLIENT_SECRET, BKEY_USER_DID (the DID of the human who should approve)
  • One-call primitive: bkey.approve(message, { scope }) → returns an EdDSA JWT on approval.
  • Verify server-side: use verifyToken(token, { issuer, scope }) from @bkey/node before acting on any approval.
  • API reference: api-reference/overview. The full OIDC endpoint surface is at /authentication/integrating-bkey.
The rest of this page explains the same thing in prose for humans.

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Install and call — 30 seconds

1. Install. 
npm install @bkey/sdk
2. Register an agent. One-time, from a machine where a human can run bkey auth login first. BKey pushes an approval to the human’s phone; on approval, credentials are printed or saved. 
bkey auth login
bkey auth setup-agent --name "My Agent" --save
--save stores the new agent as a named profile in ~/.bkey/profiles.json alongside your human session (identifier slugified from --name). Invoke with bkey <cmd> --agent to run as that agent. Use --json instead of --save to emit the raw credentials to stdout for CI secrets. 3. Request approval — one call. 
import { BKey } from '@bkey/sdk';

const bkey = new BKey({
  clientId: process.env.BKEY_CLIENT_ID!,
  clientSecret: process.env.BKEY_CLIENT_SECRET!,
  did: process.env.BKEY_USER_DID!, // the human who should approve
});

// Blocks until the human approves on their phone or denies.
const result = await bkey.approve('Delete user alice@corp', {
  scope: 'approve:action',
});

if (!result.approved) throw new Error('denied on device');
// result.accessToken is an EdDSA JWT — verify it server-side before acting.
4. Verify the token server-side (don’t trust the boolean alone): 
import { verifyToken } from '@bkey/node';

const claims = await verifyToken(result.accessToken, {
  issuer: 'https://api.bkey.id',
  scope: 'approve:action',
});
// claims.sub — verified DID of the approver
// claims.jti — unique token ID; use for replay protection
That’s the whole pattern. Drop it anywhere you need a real human in the loop. See CIBA for the full protocol and per-action-scope design rules.

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What you can build with it

BKey turns “a real human approved this” into a one-call primitive. A few concrete shapes:

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Agent payments (x402 + MPP)

Your agent hits a paid API (HTTP 402), BKey auto-detects the protocol (x402 on-chain USDC or MPP Stripe Shared Payment Token), handles spending limits + biometric approval + signing, and the agent retries with the signed credential. The agent never holds card numbers, seed phrases, or blanket spending permissions — every transaction is either inside a pre-set limit or explicitly human-authorized. See agent payments.

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Agent actions that can’t silently go rogue

Your AI agent can draft a deploy, a refund, a database change — but the action runs only after a human approves on their phone with facial biometrics. The agent never holds long-lived credentials that spend money or touch production on their own. The agent proposes; the human authorizes.

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Admin & compliance gates

Role grants, table drops, wire transfers, support overrides — gate any destructive action on a biometric approval. Every operation produces a signed, timestamped attestation bound to a specific human’s device. Auditable by default.

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MCP tool gating

Your AI assistant invokes a tool, your server pauses, the operator’s phone lights up, they approve with facial biometrics, the tool runs. Every tool invocation in your MCP server carries cryptographic evidence of consent. See MCP integration.

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Real proof-of-humanity, without the CAPTCHA guessing game

“Select all the stoplights” doesn’t prove a human did it — bots solve them and real users hate them. BKey does: for users signed up once with BKey, any sensitive form submission, signup, comment, or download can be gated on a face-verified approval. You get back a cryptographic signature, not a probabilistic bot score.

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Encrypted vault for secrets

End-to-end encrypted secrets released only after biometric approval — the plaintext never touches the server. Agents can request specific items, but only the owner can unlock them. See encryption.

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Document & transaction signing

Sign legal documents or crypto transactions with a biometric-bound key that lives in the phone’s secure enclave. Private keys never leave the device; the signature itself is the proof of human intent.

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Under the hood

  • No stored biometrics — cryptographic keys are generated from a live face scan on each use; the phone keeps a device-held secret, the face stays on the face.
  • CIBA (RFC 8958) for backchannel biometric approval.
  • EdDSA (Ed25519) signed JWTs — verify with our JWKS.
  • On-device keys in the iOS Secure Enclave / Android Keystore — private keys never leave the phone.
  • End-to-end encrypted vault payloads (X25519 ECDH + AES-256-GCM).
  • Standards-compliant OIDC — you don’t need our SDK; any OIDC-aware library works.

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Next

PathWhen
QuickstartGet to a working approve() call in 5 minutes
Integrate BKeyOur endpoint surface, for integrators who don’t want to use our SDK
CIBA one-line approvalThe core SDK pattern, with verify-token details
Agent paymentsx402 + MPP auto-detection
MCP integrationGate MCP tool calls on biometrics
EncryptionWhat’s protected at each step
Go and Rust SDKs are coming. See the GitHub repo for updates.