/// <summary>
/// Extracts a byte from data
/// </summary>
/// <param name="data">Data containg bits</param>
/// <returns>The byte hidden in data</returns>
protected byte ExtractEx(byte[] data)
{
byte info = 0;
///We will read the LSB value from data and make it part of info
///As we hide LSB of message byte first therefore we start the loop from
///then i.e. end of the array to read MSB and then right shift it to store
///the next bit
for (int i = data.Length; i > 0; i--)
{
///Shift one bit to right side so the next bit can be set
info <<= 0x1;
info |= Substitution.LsbValue(data[i - 1]);
}
return(info);
}
/// <summary>
/// Extract length from host object
/// </summary>
/// <param name="stegoObject"></param>
/// <returns></returns>
protected int ExtractLength(IHostObject hostObject)
{
///32 bytes of stego object will contain 4 bytes of legth information.
///We will read it byte by byte
byte[] lengthInfo = new byte[4];
for (int i = 0; i < 4; i++)
{
byte[] lengthBytes = new byte[8];
hostObject.Read(lengthBytes, 0, lengthBytes.Length);
///The first byte in this array will contain LSB information. We will have to
///read MSB first
for (int j = lengthBytes.Length; j > 0; j--)
{
///Shift one bit to right side so the next bit can be set
lengthInfo[i] <<= 0x1;
lengthInfo[i] |= Substitution.LsbValue(lengthBytes[j - 1]);
}
}
return(AppUtil.FromByteArray(lengthInfo));
}
