Protect ZipArchive

RadZipLibrary lets you protect a ZIP archive with a password. This help article will teach you how to use RadZipLibrary to password-protect files and how to open files that are protected with a password. To protect a ZIP archive and all ZipArchiveEntry items in it, you should specify encryption settings when creating the ZipArchive object.

RadZipLibrary supports the following encryption algorithms:

• Traditional PKWARE encryption algorithm - the settings for this encryption type are represented by the PasswordEncryptionSettings class.

• Strong AES encryption algorithm - introduced in 2024 Q1.

AES encryption (Advanced Encryption Standard) is commonly used to secure sensitive information, such as credit card numbers, passwords, and personal data. It uses a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data. AES encryption uses a fixed-length key of 128, 192, or 256 bits to encrypt and decrypt data.

• Create a Password-protected ZipArchive

• Read a Password-protected ZipArchive

Create a Password-Protected ZipArchive

In order to create a password-protected ZIP archive, you need to pass a PasswordEncryptionSettings object to the ZipArchive's constructor along with the CompressionSettings and Encoding parameter.

PasswordEncryptionSettings has a Password property of type string, which represents the used password.

Example 1: Create a password-protected ZIP archive

• C#
• VB.NET

using (Stream stream = File.Open("test.zip", FileMode.Create)) 
{ 
 
    //By default the EncryptionStrenght is 256 bits but it can be explicitly specified (EncryptionStrength.Aes128, EncryptionStrength.Aes192, and EncryptionStrength.Aes256) by passing it to the constructor 
    PasswordEncryptionSettings aesEncryptionSettings = EncryptionSettings.CreateAesPasswordEncryptionSettings(); 
 
    //You can also use the PKWARE encryption algorithm instead of the AES one 
    PasswordEncryptionSettings pkwareEncryptionSettings = EncryptionSettings.CreatePkzipPasswordEncryptionSettings(); 
 
    aesEncryptionSettings.Password = "password";  
    CompressionSettings compressionSettings = null; 
    Encoding encoding = null; 
    using (ZipArchive archive = ZipArchive.Create(stream, encoding, compressionSettings, aesEncryptionSettings)) 
    { 
        using (ZipArchiveEntry entry = archive.CreateEntry("text.txt")) 
        { 
            StreamWriter writer = new StreamWriter(entry.Open()); 
            writer.WriteLine("Hello world!"); 
            writer.Flush(); 
        } 
    } 
} 

Using stream As Stream = File.Open("test.zip", FileMode.Create) 
        'By default the EncryptionStrenght is 256 bits but it can be explicitly specified (EncryptionStrength.Aes128, EncryptionStrength.Aes192, and EncryptionStrength.Aes256) by passing it to the constructor 
        Dim aesEncryptionSettings As PasswordEncryptionSettings = EncryptionSettings.CreateAesPasswordEncryptionSettings() 
 
        'You can also use the PKWARE encryption algorithm instead of the AES one 
        Dim pkwareEncryptionSettings As PasswordEncryptionSettings = EncryptionSettings.CreatePkzipPasswordEncryptionSettings() 
 
        aesEncryptionSettings.Password = "password" 
        Dim compressionSettings As CompressionSettings = Nothing 
        Dim encoding As Encoding = Nothing 
 
        Using archive As ZipArchive = ZipArchive.Create(stream, encoding, compressionSettings, aesEncryptionSettings) 
 
            Using entry As ZipArchiveEntry = archive.CreateEntry("text.txt") 
                    Dim writer As StreamWriter = New StreamWriter(entry.Open()) 
                    writer.WriteLine("Hello world!") 
                    writer.Flush() 
            End Using 
        End Using 
End Using 

You must always dispose of the ZIP archive object when all operations that use it are completed. Telerik Support recommends that you declare and instantiate the ZIP archive object in a using statement. If it is not possible for some reason, then do not forget to call the Dispose() method when you complete all operations.

Read a Password-Protected ZipArchive

In order to open a password-protected ZipArchive, you need to pass a DefaultEncryptionSettings object with the password that was used to create the archive in the first place.

Example 2: Open and read a password-protected ZIP archive

• C#
• VB.NET

using (FileStream stream = File.Open("test.zip", FileMode.Open)) 
{  
        DecryptionSettings decryptionSettings = EncryptionSettings.CreateDecryptionSettings(); 
        decryptionSettings.PasswordRequired += (s, a) => a.Password = "password"; 
        CompressionSettings compressionSettings = null; 
        Encoding encoding = null; 
        using (ZipArchive zipArchive = ZipArchive.Read(stream, encoding, compressionSettings, decryptionSettings)) 
        { 
            // Display the list of the files in the selected zip file using the ZipArchive.Entries property.  
        } 
} 

Sub Main()   
    Using stream As FileStream = File.Open("test.zip", FileMode.Open) 
            Dim decryptionSettings As DecryptionSettings = EncryptionSettings.CreateDecryptionSettings() 
            AddHandler decryptionSettings.PasswordRequired, AddressOf DecryptionSettings_PasswordRequired 
            Dim compressionSettings As CompressionSettings = Nothing 
            Dim encoding As Encoding = Nothing 
 
            Using zipArchive As ZipArchive = ZipArchive.Read(stream, encoding, compressionSettings, decryptionSettings) 
                '  Display the list of the files in the selected zip file using the ZipArchive.Entries property.  
            End Using 
    End Using 
End Sub 
 
Private Sub DecryptionSettings_PasswordRequired(ByVal sender As Object, ByVal e As PasswordRequiredEventArgs) 
        e.Password = "passw0rd" 
End Sub 

You must always dispose of the ZIP archive object when all operations that use it are completed. We recommend that you declare and instantiate the ZIP archive object in a using statement. If it is not possible for some reason, then do not forget to call the Dispose() method when you complete all operations.