public Collection <T> Encode(Stream messageStream, string alphabet, StegoPermutationPresentation presentation, StegoPermutation stego)
{
Collection <T> result = new Collection <T>();
stego.ProgressChanged(10, 100);
T[] sortedItems = sortItems(alphabet);
stego.ProgressChanged(20, 100);
// initialize message
messageStream.Position = 0;
byte[] buffer = new byte[messageStream.Length];
messageStream.Read(buffer, 0, buffer.Length);
BigInteger message = 0;
for (int i = 0; i < buffer.Length; i++)
{
message = message * 256 + buffer[buffer.Length - 1 - i];
}
// initialize carrier
result.Clear();
for (int n = 0; n < source.Count; n++)
{
result.Add(null);
}
// update presentation control
SendOrPostCallback updatePresentationResultListDelegate = (SendOrPostCallback) delegate
{
presentation.UpdateResultList(result);
};
if (presentation.IsVisible)
{
presentation.Dispatcher.Invoke(DispatcherPriority.Normal, updatePresentationResultListDelegate, null);
}
try
{
LRArray lr = new LRArray((ulong)source.Count);
lr.set_all();
int skip = 0;
for (int indexSource = 0; indexSource < source.Count; indexSource++)
{
int cnt = source.Count - indexSource;
skip = (int)(message % cnt);
message = message / cnt;
int resultIndex = (int)lr.get_set_idx_chg((ulong)skip);
result[resultIndex] = sortedItems[indexSource];
stego.ProgressChanged(indexSource + 1, source.Count);
if (presentation.IsVisible)
{
presentation.Dispatcher.Invoke(DispatcherPriority.Normal, updatePresentationResultListDelegate, null);
Thread.Sleep(500);
}
}
}
catch (Exception ex)
{
}
return(result);
}
public void Decode(Stream messageStream, string alphabet, StegoPermutationPresentation presentation, StegoPermutation stego)
{
Dictionary <T, ulong> string2index = new Dictionary <T, ulong>();
ulong[] numList = new ulong[source.Count];
ulong[] numListInv = new ulong[source.Count];
ulong[] values = new ulong[source.Count];
stego.ProgressChanged(10, 100);
T[] sortedItems = sortItems(alphabet);
for (int i = 0; i < sortedItems.Length; i++)
{
string2index[sortedItems[i]] = (ulong)i;
}
for (int i = 0; i < numList.Length; i++)
{
numList[i] = string2index[source[i]];
}
for (int i = 0; i < numList.Length; i++)
{
numListInv[numList[i]] = (ulong)i;
}
stego.ProgressChanged(20, 100);
BigInteger message = new BigInteger(0);
BigIntegerClass messageWrapper = new BigIntegerClass(message);
// update presentation control
SendOrPostCallback updatePresentationResultNumberDelegate = (SendOrPostCallback) delegate
{
presentation.UpdateResultNumber(messageWrapper);
};
if (presentation.IsVisible)
{
presentation.Dispatcher.Invoke(DispatcherPriority.Normal, updatePresentationResultNumberDelegate, null);
}
LRArray lr = new LRArray((ulong)source.Count);
lr.set_all();
try
{
for (int carrierIndex = source.Count - 1; carrierIndex >= 0; carrierIndex--)
{
ulong v = lr.num_SRE(numList[carrierIndex]);
values[carrierIndex] = lr.num_SRE(numList[carrierIndex]);
lr.get_set_idx_chg((ulong)carrierIndex - v);
}
stego.ProgressChanged(30, 100);
message = 0;
for (int i = 1; i <= source.Count; i++)
{
message = i * message + values[numListInv[source.Count - i]];
stego.ProgressChanged(i, source.Count + 1);
if (presentation.IsVisible)
{
messageWrapper.BigIntegerStruct = message;
presentation.Dispatcher.Invoke(DispatcherPriority.Normal, updatePresentationResultNumberDelegate, null);
Thread.Sleep(500);
}
}
}
catch (Exception ex)
{
}
// convert message to stream
byte[] messageBytes = message.ToByteArray();
int cnt = messageBytes.Length;
if (messageBytes[cnt - 1] == 0)
{
cnt--;
}
messageStream.Write(messageBytes, 0, cnt);
messageStream.Position = 0;
}
