/// <summary>
/// Embed the text into the image.
/// </summary>
/// <param name="text">The text to embed.</param>
/// <param name="image">The image to embed the text into.</param>
/// <param name="sharedKey">The shared key used with the common salt.</param>
/// <param name="salt">The common salt used to generate the key.</param>
/// <returns>The image containing the embedded text.</returns>
public Bitmap EmbedText(string text, Bitmap image, string sharedKey, byte[] salt)
{
// Create a new derived key.
byte[] cryptoKey = Nequeo.Cryptography.RandomDerivedKey.Generate(sharedKey, salt);
Nequeo.Cryptography.AdvancedAES aes = new Cryptography.AdvancedAES();
// Encrypt the key.
byte[] encryptedText = aes.EncryptToMemory(Encoding.Default.GetBytes(text), cryptoKey);
string textBase64 = Nequeo.Conversion.Context.ByteArrayToHexString(encryptedText);
// Create the image.
return(Nequeo.Drawing.TextEmbedding.EmbedText(textBase64, image));
}
/// <summary>
/// Extract the text from the image.
/// </summary>
/// <param name="image">The image that contains the text to extract.</param>
/// <param name="sharedKey">The shared key used with the common salt.</param>
/// <param name="salt">The common salt used to generate the key.</param>
/// <returns>The extracted text.</returns>
public string ExtractText(Bitmap image, string sharedKey, byte[] salt)
{
// Create a new derived key.
byte[] cryptoKey = Nequeo.Cryptography.RandomDerivedKey.Generate(sharedKey, salt);
Nequeo.Cryptography.AdvancedAES aes = new Cryptography.AdvancedAES();
// Extract the text.
string textBase64 = Nequeo.Drawing.TextEmbedding.ExtractText(image);
byte[] encryptedText = Nequeo.Conversion.Context.HexStringToByteArray(textBase64);
byte[] decryptedText = aes.DecryptFromMemory(encryptedText, cryptoKey);
// Return the text.
return(Encoding.Default.GetString(decryptedText));
}
