(C#) 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.

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

Chilkat.Zip zip = new Chilkat.Zip();

// Open an unencrypted .zip
bool success = zip.OpenZip("qa_data/zips/test.zip");
if (success != true) {
    Debug.WriteLine(zip.LastErrorText);
    return;
}

// Unzip to a temp directory.
int numFilesUnzipped = zip.Unzip("qa_output/tmp");
if (numFilesUnzipped < 0) {
    Debug.WriteLine(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) {
    Debug.WriteLine(zip.LastErrorText);
    return;
}

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

Debug.WriteLine("Success.");