public static string ExtractMsg(string rawInput, Bitmap imgMap)
{
// pre-processing the hidden message
string key = KeyExtract(ref rawInput);
int[] indexList = IndexExtract(ref rawInput);
byte[] textInByte = ImgProcessing.ExtractByte(imgMap, indexList);
if (!string.IsNullOrEmpty(key))
{
// Decrypt the bytes to a string.
return(CryptoHandler.DecryptStringFromBytes_Aes(textInByte, key, CryptoHandler.IV));
}
else
{
return(Encoding.UTF8.GetString(textInByte));
}
}
// return 0 if space is not enough
public static int InsertMsg(string rawInput, Bitmap imgMap)
{
// detect if a key input exist in the raw data
string key = KeyExtract(ref rawInput);
// detect if the user input an index tag
int[] indexList = IndexExtract(ref rawInput);
byte[] textInByte;
// if the user inputs a key, encrypted the text input
if (!string.IsNullOrEmpty(key))
{
// Encrypt the string to an array of bytes.
byte[] plainByte = CryptoHandler.EncryptStringToBytes_Aes(rawInput, key, CryptoHandler.IV);
byte[] str = Encoding.UTF8.GetBytes("<STR>");
byte[] end = Encoding.UTF8.GetBytes("<END>");
textInByte = new byte[str.Length + plainByte.Length + end.Length];
Buffer.BlockCopy(str, 0, textInByte, 0, str.Length);
Buffer.BlockCopy(plainByte, 0, textInByte, str.Length, plainByte.Length);
Buffer.BlockCopy(end, 0, textInByte, end.Length + plainByte.Length, end.Length);
}
else
{
// prolong the plaintext with the header
string plaintext = "<STR>" + rawInput + "<END>";
textInByte = Encoding.UTF8.GetBytes(plaintext);
}
long availableWidth = (imgMap.Width - indexList[1]) / indexList[3];
long availableHeight = (imgMap.Height - indexList[0]) / indexList[2];
long availableSpace = (availableWidth + availableHeight) * (indexList[4] + indexList[5] + indexList[6]);
if (availableSpace >= textInByte.Length * 8 && availableHeight > 0 && availableWidth > 0)
{
ImgProcessing.InsertByte(textInByte, imgMap, indexList);
return(1);
}
else
{
return(0);
}
}