Register at the IdP

Enter your OAuth redirect URI. You'll get a client_id + secret derived from it — no storage, pure HMAC. Register the same URI at the AS so the IdP can bind the two identities in the ID-JAG.

\n`));\n\napp.post(\"/register\", async (c) => {\n const body = await c.req.parseBody();\n const redirectUri = body.redirect_uri as string;\n if (!redirectUri) return c.json({ error: \"invalid_request\", error_description: \"redirect_uri required\" }, 400);\n return c.json(await register(IDP_PREFIX, URLS.idp, redirectUri));\n});\n\n// ─── id_token minting ───────────────────────────────────────────────────────\n// reg_uri is the redirect_uri the client registered with — it's our account\n// key. At token-exchange we use it to derive the client's ID at the target AS.\n\nasync function mintIdToken(sub: string, email: string, clientId: string, regUri: string): Promise {\n return await new jose.SignJWT({ email, reg_uri: regUri })\n .setProtectedHeader({ alg: \"ES256\", kid: kp.kid })\n .setIssuer(URLS.idp)\n .setAudience(clientId)\n .setSubject(sub)\n .setIssuedAt()\n .setExpirationTime(\"1h\")\n .sign(kp.privateKey);\n}\n\n// ─── /token ─────────────────────────────────────────────────────────────────\n\napp.post(\"/token\", async (c) => {\n const body = await c.req.parseBody();\n const grantType = body.grant_type as string;\n\n if (grantType === TOKEN_EXCHANGE_GRANT) return handleTokenExchange(c, body);\n if (grantType === \"authorization_code\") return handleAuthCode(c, body);\n return c.json({ error: \"unsupported_grant_type\", error_description: grantType }, 400);\n});\n\n/**\n * RFC 8693 Token Exchange: id_token → ID-JAG.\n *\n * The app<>app binding: the id_token's `aud` is the client's IdP client_id,\n * and its `reg_uri` is the redirect_uri they registered. We derive what their\n * client_id at the AS would be (for the `audience` they're requesting) by\n * running the same HMAC the AS ran at /register. That goes into the ID-JAG's\n * `client_id` claim, which the AS will check against the Basic-auth client.\n */\nasync function handleTokenExchange(c: any, body: Record) {\n const subjectToken = body.subject_token as string;\n const subjectTokenType = body.subject_token_type as string;\n const requestedTokenType = body.requested_token_type as string;\n const audience = body.audience as string;\n const resource = body.resource as string;\n const clientId = body.client_id as string;\n const clientSecret = body.client_secret as string | undefined;\n\n if (subjectTokenType !== ID_TOKEN_TYPE) {\n return c.json({ error: \"invalid_request\", error_description: `subject_token_type must be ${ID_TOKEN_TYPE}` }, 400);\n }\n if (requestedTokenType !== ID_JAG_TOKEN_TYPE) {\n return c.json({ error: \"invalid_request\", error_description: `requested_token_type must be ${ID_JAG_TOKEN_TYPE}` }, 400);\n }\n if (!audience || !resource) {\n return c.json({ error: \"invalid_request\", error_description: \"audience and resource are required\" }, 400);\n }\n\n // Client auth: secret must re-derive from presented client_id\n if (!clientSecret || !(await validateSecret(clientId, clientSecret))) {\n return c.json({ error: \"invalid_client\", error_description: \"client authentication failed\" }, 401);\n }\n\n // Verify the id_token: signed by us, aud = this client\n let sub: string, regUri: string;\n try {\n const { payload } = await jose.jwtVerify(subjectToken, kp.publicKey, {\n issuer: URLS.idp,\n audience: clientId,\n });\n sub = payload.sub!;\n regUri = payload.reg_uri as string;\n if (!regUri) throw new Error(\"id_token missing reg_uri claim\");\n } catch (e) {\n return c.json({ error: \"invalid_grant\", error_description: `id_token verification failed: ${e instanceof Error ? e.message : e}` }, 400);\n }\n\n // Derive the client's ID at the requested AS for the requested resource.\n // The AS derived this same value at /register given (reg_uri, resource).\n const asClientId = await deriveAsClientIdFor(audience, regUri, resource);\n\n const idJag = await new jose.SignJWT({ resource, client_id: asClientId })\n .setProtectedHeader({ alg: \"ES256\", typ: \"oauth-id-jag+jwt\", kid: kp.kid })\n .setIssuer(URLS.idp)\n .setAudience(audience)\n .setSubject(sub)\n .setIssuedAt()\n .setExpirationTime(\"5m\")\n .setJti(crypto.randomUUID())\n .sign(kp.privateKey);\n\n return c.json({\n access_token: idJag,\n issued_token_type: ID_JAG_TOKEN_TYPE,\n token_type: \"N_A\",\n expires_in: 300,\n });\n}\n\n/**\n * OIDC authorization_code grant. Auth code is itself a JWT carrying PKCE\n * challenge + redirect_uri + client_id — no database needed.\n */\nasync function handleAuthCode(c: any, body: Record) {\n const code = body.code as string;\n const codeVerifier = body.code_verifier as string;\n const redirectUri = body.redirect_uri as string;\n const clientId = body.client_id as string;\n const clientSecret = body.client_secret as string | undefined;\n\n if (!clientSecret || !(await validateSecret(clientId, clientSecret))) {\n return c.json({ error: \"invalid_client\", error_description: \"invalid client credentials\" }, 401);\n }\n\n let claims: jose.JWTPayload;\n try {\n const { payload } = await jose.jwtVerify(code, kp.publicKey, {\n issuer: URLS.idp,\n audience: `${URLS.idp}/token`,\n });\n claims = payload;\n } catch (e) {\n return c.json({ error: \"invalid_grant\", error_description: `code invalid or expired: ${e instanceof Error ? e.message : e}` }, 400);\n }\n\n // Tie the code to this specific client_id + redirect_uri\n if (claims.client_id !== clientId || claims.redirect_uri !== redirectUri) {\n return c.json({ error: \"invalid_grant\", error_description: \"code was issued to a different client or redirect_uri\" }, 400);\n }\n\n // PKCE S256\n const hash = await crypto.subtle.digest(\"SHA-256\", new TextEncoder().encode(codeVerifier));\n const actualChallenge = btoa(String.fromCharCode(...new Uint8Array(hash)))\n .replace(/\\+/g, \"-\").replace(/\\//g, \"_\").replace(/=+$/, \"\");\n if (actualChallenge !== claims.code_challenge) {\n return c.json({ error: \"invalid_grant\", error_description: \"PKCE verification failed\" }, 400);\n }\n\n const idToken = await mintIdToken(claims.sub!, claims.email as string, clientId, redirectUri);\n return c.json({\n access_token: \"idp-access-token-unused\",\n id_token: idToken,\n token_type: \"Bearer\",\n expires_in: 3600,\n });\n}\n\n// ─── /authorize — validates client_id ↔ redirect_uri binding ────────────────\n\napp.get(\"/authorize\", async (c) => {\n const q = c.req.query();\n const { client_id, redirect_uri, state, code_challenge, code_challenge_method } = q;\n\n if (!redirect_uri || !code_challenge || code_challenge_method !== \"S256\") {\n return c.text(\"invalid_request: redirect_uri, code_challenge, code_challenge_method=S256 required\", 400);\n }\n // The HMAC binding: this client_id was derived from this exact redirect_uri.\n // Wrong URI → different HMAC → no match → you didn't register this.\n if (!(await validateRedirect(IDP_PREFIX, URLS.idp, client_id, redirect_uri))) {\n return c.text(`invalid_client: client_id does not match redirect_uri (register at ${URLS.idp}/register)`, 400);\n }\n\n const hidden = Object.entries({ client_id, redirect_uri, state, code_challenge })\n .filter(([, v]) => v)\n .map(([k, v]) => ``)\n .join(\"\");\n\n return c.html(`Demo IdP\n\n

Demo IdP

Client ${client_id} wants to sign you in.
redirect_uri ✓ verified

\n`);\n});\n\napp.post(\"/authorize/grant\", async (c) => {\n const body = await c.req.parseBody();\n const redirectUri = body.redirect_uri as string;\n const state = body.state as string | undefined;\n\n const code = await new jose.SignJWT({\n client_id: body.client_id as string,\n redirect_uri: redirectUri,\n code_challenge: body.code_challenge as string,\n email: DEMO_USER.email,\n })\n .setProtectedHeader({ alg: \"ES256\", kid: kp.kid })\n .setIssuer(URLS.idp)\n .setAudience(`${URLS.idp}/token`)\n .setSubject(DEMO_USER.sub)\n .setIssuedAt()\n .setExpirationTime(\"5m\")\n .sign(kp.privateKey);\n\n const dest = new URL(redirectUri);\n dest.searchParams.set(\"code\", code);\n if (state) dest.searchParams.set(\"state\", state);\n return new Response(null, { status: 302, headers: { Location: dest.toString() } });\n});\n\n// ─── Debug — wide open ──────────────────────────────────────────────────────\n\napp.get(\"/debug/mint-id-token\", async (c) => {\n const { idp } = await debugCreds();\n return c.text(await mintIdToken(DEMO_USER.sub, DEMO_USER.email, idp.client_id, DEBUG_REDIRECT_URI));\n});\n\n// Full MCP_CONFORMANCE_SERVER_CONTEXT, ready to pipe into the scenario.\napp.get(\"/debug/context\", async (c) => {\n const { idp, as } = await debugCreds();\n const idToken = await mintIdToken(DEMO_USER.sub, DEMO_USER.email, idp.client_id, DEBUG_REDIRECT_URI);\n return c.json({\n client_id: as.client_id,\n client_secret: as.client_secret,\n idp_client_id: idp.client_id,\n idp_client_secret: idp.client_secret,\n idp_id_token: idToken,\n idp_token_endpoint: `${URLS.idp}/token`,\n });\n});\n\n// ─── Index ──────────────────────────────────────────────────────────────────\n\napp.get(\"/\", (c) =>\n c.html(indexPage({\n role: \"IdP\",\n name: \"xaa-mcp-idp\",\n endpoints: [\n { method: \"GET\", path: \"/.well-known/openid-configuration\" },\n { method: \"GET\", path: \"/.well-known/jwks.json\" },\n { method: \"GET\", path: \"/register\", note: \"stateless — HMAC of your redirect_uri\" },\n { method: \"GET\", path: \"/authorize\", note: \"one-click demo login\" },\n { method: \"POST\", path: \"/token\", note: \"authorization_code + token-exchange\" },\n { method: \"GET\", path: \"/debug/mint-id-token\", note: \"skip login entirely\" },\n { method: \"GET\", path: \"/debug/context\", note: \"full MCP_CONFORMANCE_SERVER_CONTEXT\" },\n ],\n })));\n\napp.onError((err) => { throw err; });\n\nexport default app.fetch;\nif (import.meta.main) Deno.serve({ port: 3001 }, app.fetch);\n","deleted","label",[100],"permalink","https://www.val.town/x/pcarleton/xaa-mcp-idp/code/http.ts","extension","actionData","errors"]