JavaScriptSolidServer · melvincarvalho · May 10, 2026 · May 10, 2026 · May 10, 2026 · May 10, 2026
@@ -0,0 +1,112 @@
+/**
+ * Shared Nostr-key encoding helpers.
+ *
+ * Lives in its own module so both the NIP-98 verifier
+ * (`src/auth/nostr.js`) and the well-known DID-doc publisher
+ * (`src/idp/well-known-did-nostr.js`) can use it without forming a
+ * circular import.
+ */
+
+import { secp256k1 } from '@noble/curves/secp256k1';
+
+/** Multicodec varint for secp256k1-pub: 0xe7 0x01 → "e701" hex. */
+const MULTICODEC_SECP256K1_PUB_HEX = 'e701';
+
+/**
+ * Validate a secp256k1 JWK as a Nostr key and return its x-only
+ * pubkey hex. Returns `null` if the JWK isn't a Nostr-shaped key
+ * or its `y` doesn't match the BIP-340 canonical (even-y) point
+ * for the declared `x`.
+ *
+ * Why y matters: every secp256k1 x has TWO valid points (positive
+ * and negative y). Nostr uses x-only pubkeys, which by BIP-340
+ * convention always pick the even-y point. A profile that declares
+ * a JWK with the right x but the wrong y is NOT the user's Nostr
+ * key — accepting it would let an attacker plant a JWK at someone
+ * else's WebID and have the indexer publish it as theirs.
+ *
+ * The verifier in src/auth/nostr.js (jwkMatchesNostrPubkey) does
+ * the same check. Keeping the indexer in sync prevents the
+ * "indexed but verifier rejects" inconsistency that would surface
+ * as a 401 on a key the well-known endpoint had advertised.
+ */
+export function pubkeyFromValidatedJwk(jwk) {
+  if (!jwk || typeof jwk !== 'object') return null;
+  if (jwk.kty !== 'EC') return null;
+  if (jwk.crv !== 'secp256k1' && jwk.crv !== 'P-256K') return null;
+  if (typeof jwk.x !== 'string' || typeof jwk.y !== 'string') return null;
+  let xHex;
+  try {
+    xHex = Buffer.from(jwk.x.replace(/-/g, '+').replace(/_/g, '/'), 'base64')
+      .toString('hex').toLowerCase();
+  } catch { return null; }
+  if (!/^[0-9a-f]{64}$/.test(xHex)) return null;
+  let canonicalY;
+  try {
+    // Compressed SEC1 encoding for the EVEN-y point at this x.
+    const point = secp256k1.ProjectivePoint.fromHex('02' + xHex);
+    canonicalY = point.toAffine().y.toString(16).padStart(64, '0');
+  } catch { return null; }
+  let jwkYHex;
+  try {
+    jwkYHex = Buffer.from(jwk.y.replace(/-/g, '+').replace(/_/g, '/'), 'base64')
+      .toString('hex').toLowerCase();
+  } catch { return null; }
+  if (jwkYHex !== canonicalY) return null;
+  return xHex;
+}
+
+/**
+ * Decode an f-form Multikey for secp256k1-pub back into the 32-byte
+ * x-only pubkey hex. Returns null if the input isn't this shape.
+ *
+ * The f-form recipe (per CCG community#254 / did:nostr): multibase
+ * `f` (base16-lower) + multicodec `e701` + parity byte (`02`/`03`)
+ * + 32-byte xonly pubkey.
+ */
+export function decodeFFormSecp256k1(mb) {
+  if (typeof mb !== 'string' || !mb.startsWith('f')) return null;
+  const hex = mb.slice(1).toLowerCase();
+  if (!/^[0-9a-f]+$/.test(hex)) return null;
+  if (!hex.startsWith(MULTICODEC_SECP256K1_PUB_HEX)) return null;
+  const rest = hex.slice(MULTICODEC_SECP256K1_PUB_HEX.length);
+  // Expect parity byte (02/03) + 32-byte xonly = 66 hex chars.
+  if (rest.length !== 66) return null;
+  const parity = rest.slice(0, 2);
+  if (parity !== '02' && parity !== '03') return null;
+  return rest.slice(2);
+}
+
+/**
+ * Enumerate every Nostr pubkey declared in a profile's
+ * `verificationMethod` entries. Matches both encodings:
+ *   - f-form Multikey (`publicKeyMultibase`)
+ *   - JsonWebKey (`kty: EC, crv: secp256k1`) — derives x as the pubkey
+ *
+ * Returns `[ { pubkey, vm } ]` — the VM is returned alongside so
+ * callers can do further checks (`controller`, `authentication`
+ * membership, etc.) without re-parsing.
+ */
+export function extractNostrPubkeysFromProfile(profile) {
+  if (!profile || typeof profile !== 'object') return [];
+  const out = [];
+  const raw = profile.verificationMethod;
+  const vms = raw === undefined || raw === null ? []
+            : Array.isArray(raw) ? raw : [raw];
+  for (const vm of vms) {
+    if (!vm || typeof vm !== 'object') continue;
+    if (typeof vm.publicKeyMultibase === 'string') {
+      const xonly = decodeFFormSecp256k1(vm.publicKeyMultibase);
+      if (xonly) out.push({ pubkey: xonly, vm });
+    } else if (vm.publicKeyJwk && typeof vm.publicKeyJwk === 'object') {
+      // Require y to match the BIP-340 canonical point — the same
+      // check the NIP-98 verifier applies. Without this, the indexer
+      // could publish a JWK that the verifier will then reject,
+      // surfacing as a 401 on a key the well-known endpoint had
+      // advertised as authentic.
+      const xonly = pubkeyFromValidatedJwk(vm.publicKeyJwk);
+      if (xonly) out.push({ pubkey: xonly, vm });
+    }
+  }
+  return out;
+}
@@ -14,31 +14,36 @@
  *      Match by f-form Multikey or by JsonWebKey x/y coordinates. If
  *      found, authenticate as the WebID. (#399 — pairs with the
  *      LWS10-CID verifier.)
- *   2. Resolve via the existing did:nostr DID-document path
+ *   2. (IdP-only) Look up the pubkey in the local in-process index
+ *      built from `<DATA_ROOT>/.idp/accounts/_webid_index.json`.
+ *      No HTTP, no SSRF surface — direct function call. Catches
+ *      same-pod users without a third-party round-trip. (#407)
+ *   3. Resolve via the external did:nostr DID-document path
  *      (nostr.social `.well-known` + bidirectional alsoKnownAs).
- *      If found, authenticate as the WebID it points to.
- *   3. Otherwise return `did:nostr:<64-char-hex-pubkey>` as the
+ *      Used for cross-pod identities; SSRF + redirect hardened.
+ *   4. Otherwise return `did:nostr:<64-char-hex-pubkey>` as the
  *      agent identity (the original behavior).
  */
 
 import { verifyEvent, getEventHash } from '../nostr/event.js';
 import { secp256k1 } from '@noble/curves/secp256k1';
 import crypto from 'crypto';
 import { resolveDidNostrToWebId } from './did-nostr.js';
+// resolveDidNostrLocally is loaded lazily (inside the idpEnabled
+// branch) so non-IdP deployments don't pay the IdP/accounts module
+// startup cost (bcryptjs, oidc-provider helpers, etc.) just by
+// importing the NIP-98 verifier.
 import { fetchCidDocument } from './cid-doc-fetch.js';
 import { normalizeControllers } from './lws-cid.js'; // shared JSON-LD controller helper
+import { decodeFFormSecp256k1, extractNostrPubkeysFromProfile } from './nostr-keys.js'; // re-exported for back-compat
+export { extractNostrPubkeysFromProfile };
 
 // NIP-98 event kind (references RFC 7235)
 const HTTP_AUTH_KIND = 27235;
 
 // Timestamp tolerance in seconds
 const TIMESTAMP_TOLERANCE = 60;
 
-// Multicodec varint for secp256k1-pub: 0xe7 0x01 → "e701" hex.
-// Used to decode f-form Multikey verificationMethod values back into
-// the 32-byte x-only Nostr pubkey.
-const MULTICODEC_SECP256K1_PUB_HEX = 'e701';
-
 // Profile-fetch body-size cap. Matches the LWS-CID verifier; both
 // callers go through the shared fetchCidDocument helper.
 const MAX_PROFILE_BYTES = 256 * 1024;
@@ -282,9 +287,30 @@ export async function verifyNostrAuth(request) {
     return { webId: vmWebId, error: null };
   }
 
-  // Second lookup: existing did:nostr DID-document resolver. Fetches
-  // an external DID doc (e.g. nostr.social/.well-known/...) and checks
-  // bidirectional alsoKnownAs ↔ WebID linking.
+  // Second lookup: in-process local DID resolution (#407). Fast path
+  // — direct function call into the local account index, no HTTP
+  // fetch, no SSRF surface from request-controlled headers. Catches
+  // any user who's published a Nostr Multikey VM into their profile
+  // on this same pod.
+  //
+  // Gated on idpEnabled because the index reads from
+  // <DATA_ROOT>/.idp/accounts which only exists when the IdP layer
+  // is in use. On non-IdP deployments the local resolver has nothing
+  // to find and would just spin disk on every request.
+  if (request.idpEnabled) {
+    // Dynamic import: only load the IdP-accounts stack when IdP is
+    // actually enabled. Cached after first load (ESM module caching).
+    const { resolveDidNostrLocally } = await import('../idp/well-known-did-nostr.js');
+    const localWebId = await resolveDidNostrLocally(event.pubkey);
+    if (localWebId) {
+      return { webId: localWebId, error: null };
+    }
+  }
+
+  // Third lookup: external did:nostr DID-document resolver. Fetches
+  // a DID doc from the configured external resolver (nostr.social) and
+  // checks bidirectional alsoKnownAs ↔ WebID linking. Used only for
+  // cross-pod identities (the local case is handled above).
   const resolvedWebId = await resolveDidNostrToWebId(event.pubkey);
   if (resolvedWebId) {
     return { webId: resolvedWebId, error: null };
@@ -599,23 +625,6 @@ function findNostrVmInProfile(profile, pubkeyHex, baseUrl) {
   return null;
 }
 
-/**
- * Decode an f-form Multikey for secp256k1-pub back into the 32-byte
- * x-only pubkey hex. Returns null if the input isn't this shape.
- */
-function decodeFFormSecp256k1(mb) {
-  if (typeof mb !== 'string' || !mb.startsWith('f')) return null;
-  const hex = mb.slice(1).toLowerCase();
-  if (!/^[0-9a-f]+$/.test(hex)) return null;
-  if (!hex.startsWith(MULTICODEC_SECP256K1_PUB_HEX)) return null;
-  const rest = hex.slice(MULTICODEC_SECP256K1_PUB_HEX.length);
-  // Expect parity byte (02/03) + 32-byte xonly = 66 hex chars.
-  if (rest.length !== 66) return null;
-  const parity = rest.slice(0, 2);
-  if (parity !== '02' && parity !== '03') return null;
-  return rest.slice(2);
-}
-
 function hexToBase64url(hex) {
   return Buffer.from(hex, 'hex').toString('base64')
     .replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');