Protecting Your License File - Purchase

Your license is embedded in the applications you develop, which presents a potential security risk. Unauthorized individuals could potentially locate and copy or leak the license. While embedding the license as an internal resource offers some protection, the original file can still be extracted from the deployment package.

This page provides code examples to help you secure your license file more effectively by using encryption. Please select one of the examples below:

C# example

public void EncryptDecryptLicense()
{
    string encryptedFilePath = MyDir + "EncryptedLicense.txt";

    // Load the contents of the license into a byte array.
    byte[] licBytes = File.ReadAllBytes("YourLicense.lic");
    // Use this key only once for this license file.
    // To protect another file first generate a new key.
    byte[] key = GenerateKey(licBytes.Length);

    // Write the encrypted license to disk.
    File.WriteAllBytes(encryptedFilePath, EncryptDecryptLicense(licBytes, key));

    // Load the encrypted license and decrypt it using the key.
    byte[] decryptedLicense;
    decryptedLicense = EncryptDecryptLicense(File.ReadAllBytes(encryptedFilePath), key);

    // Load the decrypted license into a stream and set the license.
    MemoryStream licenseStream = new MemoryStream(decryptedLicense);

    License license = new License();
    license.SetLicense(licenseStream);
}

/// <summary>
/// A method used for encrypting and decrypting data using XOR.
/// </summary>
public byte[] EncryptDecryptLicense(byte[] licBytes, byte[] key)
{
    byte[] output = new byte[licBytes.Length];

    for (int i = 0; i < licBytes.Length; i++)
        output[i] = Convert.ToByte(licBytes[i] ^ key[i]);

    return output;
}

/// <summary>
/// Generates a random key the same length as the license (a one time pad).
/// </summary>
public byte[] GenerateKey(long size)
{
    RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
    byte[] strongBytes = new Byte[size];
    rng.GetBytes(strongBytes);

    return strongBytes;
}

Questions?

If you have any questions or problems, please feel free to contact our sales support who will be glad to assist.