(Node.js) Encrypt Already Existing Zip

To encrypt an already existing non-encrypted .zip, the application must open the .zip, set the encryption related properties, and then re-write.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This requires the Chilkat Zip API to have been previously unlocked.
    // See Unlock Chilkat Zip for sample code.

    var zip = new chilkat.Zip();

    // Open an unencrypted .zip
    var success = zip.OpenZip("qa_data/zips/test.zip");
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // Unzip to a temp directory.
    var numFilesUnzipped = zip.Unzip("qa_output/tmp");
    if (numFilesUnzipped < 0) {
        console.log(zip.LastErrorText);
        return;
    }

    // Clear the zip object.
    zip.NewZip("qa_output/aesTest.zip");

    // Indicate that 128-bit AES encryption is to be used when writing the .zip
    zip.Encryption = 4;
    zip.EncryptKeyLength = 128;

    // Set the password.
    zip.EncryptPassword = "secret";

    // Append the files.
    zip.AppendFromDir = "qa_output/tmp";
    success = zip.AppendFiles("*.*",true);
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    // Write the .zip and close it.
    success = zip.WriteZipAndClose();
    if (success !== true) {
        console.log(zip.LastErrorText);
        return;
    }

    console.log("Success.");

}

chilkatExample();