Refactor chat system to remove E2EE and simplify messaging

Removed all E2EE chat endpoints, crypto logic, and related API routes, transitioning chat to plain text storage and transport. Updated chat send/receive endpoints to use signed actions and enforce DM privacy settings. Cleaned up Swarm chat inbox, key management, and related debug endpoints. Updated user profile to support DM privacy, improved search for handle queries, and refactored conversation/message logic to support the new model. Migrated bot settings and privacy settings to new locations.

src/lib/auth/verify-signature.ts

@@ -29,7 +29,39 @@ export interface SignedAction {
 }
 
 /**
- * Verify a signed user action
+ * Verify a signed action against a specific public key
+ */
+export async function verifyActionSignature(signedAction: SignedAction, publicKeyStr: string): Promise<boolean> {
+  try {
+    const { sig, ...payload } = signedAction;
+    const canonicalString = canonicalize(payload);
+    const encoder = new TextEncoder();
+    const dataBytes = encoder.encode(canonicalString);
+
+    // Convert signature from Base64Url to buffer
+    const sigBase64 = base64UrlToBase64(sig);
+    const sigBuffer = Buffer.from(sigBase64, 'base64');
+
+    // Import public key (stored as SPKI Base64)
+    const publicKey = await importPublicKey(publicKeyStr);
+
+    return await cryptoSubtle.verify(
+      {
+        name: 'ECDSA',
+        hash: { name: 'SHA-256' },
+      },
+      publicKey,
+      sigBuffer,
+      dataBytes
+    );
+  } catch (error) {
+    console.error('[Verify] Crypto exception:', error);
+    return false;
+  }
+}
+
+/**
+ * Verify a signed user action (looks up user in DB)
  * 
  * @param signedAction - The signed action payload
  * @returns The user if signature is valid and not replayed
@@ -48,6 +80,7 @@ export async function verifyUserAction(signedAction: SignedAction): Promise<{
   // 1. FRESHNESS CHECK (Fail fast before DB/Crypto)
   const now = Date.now();
   const diff = Math.abs(now - payload.ts);
+  // Allow 5 minutes clock skew
   const fiveMinutesMs = 5 * 60 * 1000;
 
   if (diff > fiveMinutesMs) {
@@ -60,8 +93,6 @@ export async function verifyUserAction(signedAction: SignedAction): Promise<{
   });
 
   if (!user) {
-    // If federation, we might need to look up in remote_identity_cache here.
-    // For now, assume local user or user must exist in users table (synced).
     return { valid: false, error: 'User not found' };
   }
 
@@ -70,60 +101,34 @@ export async function verifyUserAction(signedAction: SignedAction): Promise<{
   }
 
   // 3. CRYPTOGRAPHIC VERIFICATION
-  try {
-    const canonicalString = canonicalize(payload);
-    const encoder = new TextEncoder();
-    const dataBytes = encoder.encode(canonicalString);
+  const isValid = await verifyActionSignature(signedAction, user.publicKey);
 
-    // Convert signature from Base64Url to buffer
-    const sigBase64 = base64UrlToBase64(sig);
-    const sigBuffer = Buffer.from(sigBase64, 'base64');
-
-    // Import public key (stored as SPKI Base64 in DB)
-    const publicKey = await importPublicKey(user.publicKey);
-
-    const isValid = await cryptoSubtle.verify(
-      {
-        name: 'ECDSA',
-        hash: { name: 'SHA-256' },
-      },
-      publicKey,
-      sigBuffer,
-      dataBytes
-    );
-
-    if (!isValid) {
-      return { valid: false, error: 'INVALID_SIGNATURE' };
-    }
-
-    // 4. ACTION ID HASH COMPUTATION
-    // SHA-256(canonicalPayload)
-    // We use the same canonical string we just verified.
-    const actionIdHash = crypto.createHash('sha256').update(canonicalString).digest('hex');
-
-    // 5. REPLAY PROTECTION (DB)
-    try {
-      await db.insert(signedActionDedupe).values({
-        actionId: actionIdHash,
-        did: payload.did,
-        nonce: payload.nonce,
-        ts: payload.ts,
-      });
-    } catch (err: any) {
-      // Check for unique constraint violation (duplicate key)
-      if (err.code === '23505') { // Postgres unique_violation code
-        return { valid: false, error: 'REPLAYED_NONCE' };
-      }
-      console.error('[Verify] Dedupe error:', err);
-      throw err; // Internal error
-    }
-
-    return { valid: true, user };
-
-  } catch (error) {
-    console.error('[Verify] Verification exception:', error);
-    return { valid: false, error: 'VERIFICATION_ERROR' };
+  if (!isValid) {
+    return { valid: false, error: 'INVALID_SIGNATURE' };
   }
+
+  // 4. ACTION ID HASH COMPUTATION
+  const canonicalString = canonicalize(payload);
+  const actionIdHash = crypto.createHash('sha256').update(canonicalString).digest('hex');
+
+  // 5. REPLAY PROTECTION (DB)
+  try {
+    await db.insert(signedActionDedupe).values({
+      actionId: actionIdHash,
+      did: payload.did,
+      nonce: payload.nonce,
+      ts: payload.ts,
+    });
+  } catch (err: any) {
+    // Check for unique constraint violation (duplicate key)
+    if (err.code === '23505') { // Postgres unique_violation code
+      return { valid: false, error: 'REPLAYED_NONCE' };
+    }
+    console.error('[Verify] Dedupe error:', err);
+    throw err; // Internal error
+  }
+
+  return { valid: true, user };
 }
 
 /**