Change Password of a PDF File

Change Password of a PDF File

If you want to change the password of a PDF file from “owner” to “newowner” try the next code snippet:

1. Select a PDF file.
2. Create a ‘FileReader’.
3. The AsposePdfChangePassword function is executed.
4. The name of the resulting file is set, in this example “ResultPdfChangePassword.pdf”.
5. Next, if the ‘json.errorCode’ is 0, then your DownloadFile is given the name you specified earlier. If the ‘json.errorCode’ parameter is not equal to 0 and, accordingly, there will be an error in your file, then information about such an error will be contained in the ‘json.errorText’ file.
6. As a result, the DownloadFile function generates a link and allows you to download the resulting file to the user’s operating system.

    var ffilePdfChangePassword = function (e) {
      const file_reader = new FileReader();
      file_reader.onload = (event) => {
        /*Change passwords a PDF-file from "owner" to "newowner" and save the "ResultPdfChangePassword.pdf"*/
        const json = AsposePdfChangePassword(event.target.result, e.target.files[0].name, "owner", "newuser", "newowner", "ResultPdfChangePassword.pdf");
        if (json.errorCode == 0) document.getElementById('output').textContent = json.fileNameResult;
        else document.getElementById('output').textContent = json.errorText;
        /*Make a link to download the result file*/
        DownloadFile(json.fileNameResult, "application/pdf");
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };

Using Web Workers

  /*Create Web Worker*/
    const AsposePDFWebWorker = new Worker("AsposePDFforJS.js");
    AsposePDFWebWorker.onerror = evt => console.log(`Error from Web Worker: ${evt.message}`);
    AsposePDFWebWorker.onmessage = evt => document.getElementById('output').textContent = 
      (evt.data == 'ready') ? 'loaded!' :
        (evt.data.json.errorCode == 0) ? `Result:\n${DownloadFile(evt.data.json.fileNameResult, "application/pdf", evt.data.params[0])}` : `Error: ${evt.data.json.errorText}`;

    /*Event handler*/
    const ffilePdfChangePassword = e => {
      const file_reader = new FileReader();
      file_reader.onload = event => {
        const ownerPassword = 'owner'; /*Owner password*/
        const newUserPassword = "newuser"; /*New user password*/
        const newOwnerPassword = "newowner"; /*New owner password*/
        /*Change passwords a PDF-file from "owner" to "newowner" and save the "ResultPdfChangePassword.pdf" - Ask Web Worker*/
        AsposePDFWebWorker.postMessage({ "operation": 'AsposePdfChangePassword', "params": [event.target.result, e.target.files[0].name, ownerPassword, newUserPassword, newOwnerPassword, "ResultPdfChangePassword.pdf"] }, [event.target.result]);
      };
      file_reader.readAsArrayBuffer(e.target.files[0]);
    };
  /// [Code snippet]

    /*Make a link to download the result file*/
    const DownloadFile = (filename, mime, content) => {
        mime = mime || "application/octet-stream";
        var link = document.createElement("a"); 
        link.href = URL.createObjectURL(new Blob([content], {type: mime}));
        link.download = filename;
        link.innerHTML = "Click here to download the file " + filename;
        document.body.appendChild(link); 
        document.body.appendChild(document.createElement("br"));
        return filename;
      }