Encrypt External Files

HTML Executable allows you to provide enhanced security to your ebooks or publications by encrypting external files. This feature is particularly beneficial for large source files like audio and video, which you may want to keep outside the ebook application / publication yet protected against copying. HTML Executable ensures that your encrypted files can only be accessed by your HTML application, thereby preventing unwanted duplication of your resources.

Setting files as external files

In the `File Manager`, choose the files you want to keep outside the HTML application's EXE file. They will be considered as "External Files".

Encrypting Your External Files

To encrypt your external files, follow the steps below:

1.Go to the `File Manager` and click on `Encrypt External Files`. You don't need to select any specific file—HTML Executable will automatically list all external files for you.

> Note: External files are not automatically encrypted during the publication compilation because they are not included in the compilation process. Hence, you need to manually encrypt them as explained.

ØThe `Encrypt External Files` utility will display all the external files listed in the `Source Files` column.

ØEncrypted external files will be copied to the folder specified in the `File Properties`, usually the same folder as the publication `.EXE` file or a subfolder. The exact destination is displayed in the `Destination Files` column.

ØYou might not want to encrypt all files—only those marked with a checkmark will be processed. Use the `Check All` button to select or deselect all files.

ØClick on `Encrypt Files Now` to start the encryption process. A progress dialog box will be displayed during this operation, which could take some time depending on the size of your source files.

Understanding Encrypted Files

All encrypted external files adopt the `.HEEC` extension and are uniquely associated with your publication. For instance, if you have an original external file named `video.mp4`, the encrypted version of this file would be named `video.mp4.heec`.

Updating Your Encrypted Files

Should you modify the source files, remember to use the `Encrypt External Files` utility again to re-encrypt them. As the compilation process doesn't involve external files, you must manually re-encrypt them.

⚠️ Warning: Encrypted files cannot be shared between different publications because they each have a unique encryption key. Moreover, always keep your original source files in a safe place, as HTML Executable does not offer a decryption feature.

Accessing Encrypted Files from the Publication

Your publication can automatically load external encrypted files — it recognizes the `.HEEC` extension — in the same manner it would load normal external files. For more information on how to deploy external files with your ebook EXE file, please refer to the relevant `External Files` topic in the documentation.

Through these steps, HTML Executable offers you a robust mechanism to protect your valuable content while ensuring seamless access within your ebook.