From f3739231707269623fc31b5ed6ef5ae1a787bfb1 Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Wed, 1 Apr 2026 18:20:52 +0200
Subject: [PATCH] Encrypt pdf data when merging the same pdf (bug 2028369)

---
 src/core/editor/pdf_editor.js | 15 +++++++++++--
 test/unit/api_spec.js         | 41 +++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/src/core/editor/pdf_editor.js b/src/core/editor/pdf_editor.js
index 585c2eaf4..cd867aab3 100644
--- a/src/core/editor/pdf_editor.js
+++ b/src/core/editor/pdf_editor.js
@@ -108,8 +108,16 @@ class XRefWrapper {
 }
 
 class PDFEditor {
+  // Whether the edited PDF contains only one file. This is used to determine if
+  // we can handle some potential duplications.
+  // For example, there are no obvious way to dedup page labels when merging
+  // multiple PDF files.
   hasSingleFile = false;
 
+  // Whether the edited PDF contains multiple files. This is used to determine
+  // if we can preserve some information such as passwords.
+  isSingleFile = false;
+
   #newAnnotationsParams = null;
 
   currentDocument = null;
@@ -563,6 +571,9 @@ class PDFEditor {
   async extractPages(pageInfos, annotationStorage, handler, task) {
     const promises = [];
     let newIndex = 0;
+    this.isSingleFile =
+      pageInfos.length === 1 ||
+      pageInfos.every(info => info.document === pageInfos[0].document);
     this.hasSingleFile = pageInfos.length === 1;
     const allDocumentData = [];
 
@@ -2323,7 +2334,7 @@ class PDFEditor {
    */
   #makeInfo() {
     const infoMap = new Map();
-    if (this.hasSingleFile) {
+    if (this.isSingleFile) {
       const {
         xref: { trailer },
       } = this.oldPages[0].documentData.document;
@@ -2356,7 +2367,7 @@ class PDFEditor {
    * @returns {Promise<[Dict|null, CipherTransformFactory|null, Array|null]>}
    */
   async #makeEncrypt() {
-    if (!this.hasSingleFile) {
+    if (!this.isSingleFile) {
       return [null, null, null];
     }
     const { documentData } = this.oldPages[0];
diff --git a/test/unit/api_spec.js b/test/unit/api_spec.js
index 217bd677d..27ca2ed5c 100644
--- a/test/unit/api_spec.js
+++ b/test/unit/api_spec.js
@@ -6982,5 +6982,46 @@ small scripts as well as for`);
         await newLoadingTask.destroy();
       });
     });
+
+    describe("extract pages from password-protected PDF (bug 2028369)", function () {
+      it("should preserve password protection when merging the same pdf", async function () {
+        const loadingTask = getDocument(
+          buildGetDocumentParams("pr6531_2.pdf", { password: "asdfasdf" })
+        );
+        const pdfDoc = await loadingTask.promise;
+
+        const data = await pdfDoc.extractPages([
+          { document: null },
+          { document: null },
+        ]);
+        await loadingTask.destroy();
+
+        // Opening the result without a password must fail.
+        // Use a copy so the underlying ArrayBuffer is not detached before the
+        // second getDocument call below.
+        const passwordNeededLoadingTask = getDocument(data.slice());
+        await passwordNeededLoadingTask.promise.then(
+          function () {
+            // Shouldn't get here.
+            expect(false).toEqual(true);
+          },
+          function (err) {
+            expect(err).toBeInstanceOf(PasswordException);
+            expect(err.code).toEqual(PasswordResponses.NEED_PASSWORD);
+          }
+        );
+        await passwordNeededLoadingTask.destroy();
+
+        // Opening the result with the correct password must succeed.
+        const passwordAcceptedLoadingTask = getDocument({
+          data,
+          password: "asdfasdf",
+        });
+        const newPdfDoc = await passwordAcceptedLoadingTask.promise;
+        expect(newPdfDoc).toBeInstanceOf(PDFDocumentProxy);
+        expect(newPdfDoc.numPages).toEqual(2);
+        await passwordAcceptedLoadingTask.destroy();
+      });
+    });
   });
 });