[CRITICAL] fix(security): scope legacy-key cleanup to authenticated user's own keys

src/app/api/cleanup/legacy-keys/route.js

@@ -1,103 +1,117 @@
 import { NextResponse } from 'next/server';
-import { createSupabaseClient } from '@/lib/supabase.js';
+import { createSupabaseServerClient } from '@/lib/supabase.js';
+import { createServiceRoleClient } from '@/lib/supabase/service-role.js';
 
 
 export async function DELETE(request) {
 	try {
-		// Get supabase client (will use cookies automatically)
-		const supabase = createSupabaseClient();
-
-		// Verify user is authenticated with better error handling
-		const { data: { session } } = await supabase.auth.getSession();
-		
-		if (!session || !session.user) {
-			console.error('Authentication failed - no valid session found');
+		// Use createSupabaseServerClient (reads cookies server-side) and validate
+		// with getUser() rather than getSession() to ensure the JWT is re-verified
+		// against the Supabase Auth server and cannot be spoofed via cookie tampering.
+		const supabase = await createSupabaseServerClient();
+		const { data: { user }, error: authError } = await supabase.auth.getUser();
+
+		if (authError || !user) {
+			console.error('Authentication failed - no valid user found');
 			return NextResponse.json({ error: 'Unauthorized - No valid session', details: 'Please login again' }, { status: 401 });
 		}
-
-		const userId = session.user.id;
-		console.log(`Authenticated user ${userId} requesting legacy key cleanup`);
-
-		// Find user public keys that are not ML-KEM-1024 format
-		// We can detect this by looking at the key size - ML-KEM-1024 keys are 1568 bytes
-		// when decoded from Base64
-		const { data: legacyKeys, error: findError } = await supabase
+
+		// Resolve the internal user ID from the Supabase Auth UUID.
+		const serviceRoleClient = createServiceRoleClient();
+		const { data: internalUser, error: internalUserError } = await serviceRoleClient
+			.from('users')
+			.select('id')
+			.eq('auth_user_id', user.id)
+			.single();
+
+		if (internalUserError || !internalUser) {
+			console.error('User record not found for auth_user_id:', user.id);
+			return NextResponse.json({ error: 'User not found' }, { status: 404 });
+		}
+
+		const internalUserId = internalUser.id;
+		console.log(`Authenticated user ${internalUserId} requesting legacy key cleanup (own keys only)`);
+
+		// SECURITY FIX: Scope the query to the authenticated user's keys ONLY.
+		// Previously the query fetched ALL user_public_keys without a user_id filter,
+		// allowing any authenticated user to delete other users' public keys — a
+		// privilege-escalation / denial-of-service against the entire user base.
+		const { data: legacyKeys, error: findError } = await serviceRoleClient
 			.from('user_public_keys')
-			.select('*');
-
+			.select('*')
+			.eq('user_id', internalUserId);
+
 		if (findError) {
 			console.error('Error finding legacy keys:', findError);
 			return NextResponse.json({ error: findError.message }, { status: 500 });
 		}
-		
+
 		// Function to check if a key is valid ML-KEM-1024 format
 		const isValidMlKem1024Key = (/** @type {any} */ key) => {
 			try {
 				// Skip if no public_key
 				if (!key.public_key) return false;
-				
+
 				// Check for obvious ML-KEM-1024 marker
 				if (key.public_key.includes('ML-KEM-1024')) return true;
-				
+
 				// Estimate decoded size by base64 length
 				// Base64 encodes 3 bytes in 4 characters, so decode length ≈ (base64Length * 3) / 4
 				const estimatedBytes = (key.public_key.length * 3) / 4;
-				
+
 				// ML-KEM-1024 keys are 1568 bytes when decoded
 				// Use a range to account for some variation
 				const isSizeValid = estimatedBytes >= 1550 && estimatedBytes <= 1590;
-				
+
 				// Additional format checks for more aggressive detection
-				// Invalid keys often have unusual patterns or characters
-
 				// 1. Check for invalid base64 characters
 				const hasInvalidChars = /[^A-Za-z0-9+/=]/.test(key.public_key);
-				
+
 				// 2. Check for patterns that indicate corrupted keys
 				const hasCorruptedPattern = key.public_key.includes('null') ||
 										   key.public_key.includes('undefined') ||
 										   key.public_key.includes('[object');
-				
+
 				// 3. Check for keys that are too clean (all the same character)
 				const tooManyRepeats = /(.)\1{20,}/.test(key.public_key);
-
-				// A valid key must have the right size and not trigger any of the warning flags
+
 				return isSizeValid && !hasInvalidChars && !hasCorruptedPattern && !tooManyRepeats;
 			} catch (e) {
 				console.error('Error checking key format:', e);
 				return false;
 			}
 		};
-		
-		// Filter for non-ML-KEM-1024 keys
+
+		// Filter for non-ML-KEM-1024 keys belonging to the authenticated user
 		const nonMlKem1024Keys = legacyKeys.filter(key => !isValidMlKem1024Key(key));
-		
-		console.log(`Found ${nonMlKem1024Keys.length} legacy keys out of ${legacyKeys.length} total keys`);
-		
+
+		console.log(`Found ${nonMlKem1024Keys.length} legacy keys out of ${legacyKeys.length} total keys for user ${internalUserId}`);
+
 		if (nonMlKem1024Keys.length === 0) {
 			return NextResponse.json({
 				message: 'No legacy keys found',
 				updatedCount: 0
 			});
 		}
-		
-		// For each legacy key, delete it from the database
-		// The user will need to reset their key to the proper format
+
+		// Delete only the authenticated user's legacy keys.
+		// The extra .eq('user_id', internalUserId) is a defence-in-depth guard.
 		let deletedCount = 0;
-		
+
 		for (const key of nonMlKem1024Keys) {
-			const { error: deleteError } = await supabase
+			const { error: deleteError } = await serviceRoleClient
 				.from('user_public_keys')
 				.delete()
-				.eq('id', key.id);
-
+				.eq('id', key.id)
+				.eq('user_id', internalUserId); // defence-in-depth ownership check
+
 			if (deleteError) {
 				console.error(`Error deleting legacy key ${key.id}:`, deleteError);
 			} else {
 				deletedCount++;
 			}
 		}
-		
+
 		return NextResponse.json({
 			message: 'Successfully deleted legacy keys',
 			deletedCount,
@@ -110,4 +124,4 @@ export async function DELETE(request) {
 			{ status: 500 }
 		);
 	}
-}
+}