For security reasons, Adobe recommends that you lock a PDF from editing, copying, sharing and printing, Why should I use a password-protected PDF? It is important to understand that a PDF file is different from the HTML page it is stored in and is protected with special characters and features. The special characters used in Adobe Acrobat applications such as Reader, Acrobat Pro, and Acrobat X, protect the PDF file from unauthorized access and provide further protection from copying or using other PDF components, or from using PDF services (such as the E-Mail function) that may compromise the security of the file. Password-protected PDFs and PDF security with AES encryption require encryption and decryption keys. When a person accesses the PDF document, it requires a new key to be created. In most instances, the key is saved to a file in a different location. Once again, this protects the integrity of the file. An Encryption Key (sometimes referred to as an encryption certificate or encryption key) is a file(s) that has the same content as the files from which the key is created or that has the same name as the key. When you encrypt or decrypt a PDF file, the content of the key is replaced with a file that has the same content. These file(s), or key files, need to be stored either on your local Windows computer or encrypted by a password or two-step authentication and have unique filenames. A PDF file is usually encrypted using an AES cipher. A key file consists of the same key and a file(s) with the same content. Keys are usually saved in the cloud. Most PDF documents will come with a separate file with the content of the key. To copy or open the PDF document, a person would save the content of the .pdf key as the file(s) or key files to their hard drive. How to Lock a PDF From Editing or Copying — Smallpdf.com Step 1. Lock PDF from Editing When the PDF is loaded on PDF element, go to the “Protect” tab on the toolbar. Select the “Set Password” option. This will lock the PDF from editing. For security reasons, Adobe recommends that you lock a PDF from editing, copying, sharing and printing, which may help protect the file data. May 20, 2023 — Go to the Protect PDF tool. · Drag and drop your PDF into the toolbox.