From 1d6511b043cc415018bad04d64787450f09a1f7e Mon Sep 17 00:00:00 2001
From: Reece Browne <reecebrowne1995@gmail.com>
Date: Mon, 9 Dec 2024 13:20:08 +0000
Subject: [PATCH] Check if file is encrypted without password

---
 .../static/js/multitool/DecryptFiles.js       | 80 +++++++++++--------
 .../static/js/multitool/PdfContainer.js       | 16 +++-
 2 files changed, 60 insertions(+), 36 deletions(-)

diff --git a/src/main/resources/static/js/multitool/DecryptFiles.js b/src/main/resources/static/js/multitool/DecryptFiles.js
index f050aec1..509c1acd 100644
--- a/src/main/resources/static/js/multitool/DecryptFiles.js
+++ b/src/main/resources/static/js/multitool/DecryptFiles.js
@@ -1,34 +1,30 @@
 export class DecryptFile {
-  async decryptFile(file) {
+  async decryptFile(file, requiresPassword) {
     try {
-      const password = prompt(`${window.translations.passwordPrompt}`);
-
-      if (password === null) {
-        // User cancelled
-        console.error(`Password prompt cancelled for PDF: ${file.name}`);
-        this.showErrorBanner(
-          `${window.translations.cancelled.replace('{0}', file.name)}`,
-          '',
-          `${window.translations.unexpectedError}`
-        );
-        return null; // No file to return
-      }
-
-      if (!password) {
-        // No password provided
-        console.error(`No password provided for encrypted PDF: ${file.name}`);
-        this.showErrorBanner(
-          `${window.translations.noPassword.replace('{0}', file.name)}`,
-          '',
-          `${window.translations.unexpectedError}`
-        );
-        return null; // No file to return
-      }
-
       const formData = new FormData();
       formData.append('fileInput', file);
-      formData.append('password', password);
+      if (requiresPassword) {
+        const password = prompt(`${window.translations.passwordPrompt}`);
 
+        if (password === null) {
+          // User cancelled
+          console.error(`Password prompt cancelled for PDF: ${file.name}`);
+          return null; // No file to return
+        }
+
+        if (!password) {
+          // No password provided
+          console.error(`No password provided for encrypted PDF: ${file.name}`);
+          this.showErrorBanner(
+            `${window.translations.noPassword.replace('{0}', file.name)}`,
+            '',
+            `${window.translations.unexpectedError}`
+          );
+          return null; // No file to return
+        }
+
+        formData.append('password', password);
+      }
       // Send decryption request
       const response = await fetch('/api/v1/security/remove-password', {
         method: 'POST',
@@ -64,17 +60,35 @@ export class DecryptFile {
   async checkFileEncrypted(file) {
     try {
       pdfjsLib.GlobalWorkerOptions.workerSrc = './pdfjs-legacy/pdf.worker.mjs';
-      const arrayBuffer = await file.arrayBuffer(); // Convert file to ArrayBuffer
-      await pdfjsLib.getDocument({
-        data: arrayBuffer,
-        password: '',
-      }).promise;
+      const arrayBuffer = await file.arrayBuffer();
+      const arrayBufferForPdfLib = arrayBuffer.slice(0);
 
-      return false; // File is not encrypted
+      const loadingTask = pdfjsLib.getDocument({
+        data: arrayBuffer,
+      });
+
+      await loadingTask.promise;
+
+      try {
+        //Uses PDFLib.PDFDocument to check if unpassworded but encrypted
+        const pdfDoc = await PDFLib.PDFDocument.load(arrayBufferForPdfLib);
+        return {isEncrypted: false, requiresPassword: false};
+      } catch (error) {
+        if (error.message.includes('Input document to `PDFDocument.load` is encrypted')) {
+          return {isEncrypted: true, requiresPassword: false};
+        }
+        console.error('Error checking encryption:', error);
+        throw new Error('Failed to determine if the file is encrypted.');
+      }
     } catch (error) {
       if (error.name === 'PasswordException') {
-        return true; // File is encrypted
+        if (error.code === pdfjsLib.PasswordResponses.NEED_PASSWORD) {
+          return {isEncrypted: true, requiresPassword: true};
+        } else if (error.code === pdfjsLib.PasswordResponses.INCORRECT_PASSWORD) {
+          return {isEncrypted: true, requiresPassword: false};
+        }
       }
+
       console.error('Error checking encryption:', error);
       throw new Error('Failed to determine if the file is encrypted.');
     }
diff --git a/src/main/resources/static/js/multitool/PdfContainer.js b/src/main/resources/static/js/multitool/PdfContainer.js
index f7fa2536..bbc664f7 100644
--- a/src/main/resources/static/js/multitool/PdfContainer.js
+++ b/src/main/resources/static/js/multitool/PdfContainer.js
@@ -178,9 +178,19 @@ class PdfContainer {
 
       try {
         let decryptedFile = files[i];
-
-        if (decryptedFile.type === 'application/pdf' && (await this.decryptFile.checkFileEncrypted(decryptedFile))) {
-          decryptedFile = await this.decryptFile.decryptFile(decryptedFile);
+        let isEncrypted = false;
+        let requiresPassword = false;
+        await this.decryptFile
+          .checkFileEncrypted(decryptedFile)
+          .then((result) => {
+            isEncrypted = result.isEncrypted;
+            requiresPassword = result.requiresPassword;
+          })
+          .catch((error) => {
+            console.error(error);
+          });
+        if (decryptedFile.type === 'application/pdf' && isEncrypted) {
+          decryptedFile = await this.decryptFile.decryptFile(decryptedFile, requiresPassword);
           if (!decryptedFile) {
             throw new Error('File decryption failed.');
           }