public string ComputeChecksumAsync(IComputeChecksumCallback callback)
{
if (isDir_)
{
checksum_ = "";
}
else
{
FileStream fstr = null;
try
{
fstr = new FileStream(name_, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
MD5CryptoServiceProvider md5er = new MD5CryptoServiceProvider();
int bufsize = 64 * 1024; //64K Buffer
byte[] buf = new byte[bufsize];
long curpos = 0;
while (true)
{
int readCount = fstr.Read(buf, 0, bufsize);
if (readCount < bufsize)
{
md5er.TransformFinalBlock(buf, 0, readCount);
curpos = size_;
break;
}
else
{
md5er.TransformBlock(buf, 0, readCount, buf, 0);
curpos += readCount;
}
if (callback != null)
{
if (!callback.RaiseCallback(curpos, size_))
{
throw new Exception("Checksum computation will be aborted by user.");
}
}
}
StringBuilder md5str = new StringBuilder();
foreach (byte b in md5er.Hash)
{
md5str.AppendFormat("{0:X2}", b);
}
checksum_ = md5str.ToString();
}
catch (Exception ex)
{
return(ex.Message);
}
finally
{
if (fstr != null)
{
fstr.Close();
}
}
}
return(null);
}
private string ComputeValidator( string strURL, string strUserAgent )
{
string strRandom = String.Format( "{0:X8}", new Random().Next() );
byte [] abRandom = Encoding.ASCII.GetBytes( strRandom );
byte [] abStatic =
Convert.FromBase64String( "ROkjAaKid4EUF5kGtTNn3Q==" );
int p = 0;
for( int i = 0; i < 3 && p != -1; i++ )
p = strURL.IndexOf( '/', p + 1 );
byte [] abURL = Encoding.ASCII.GetBytes( strURL.Substring( p ) );
byte [] abUA = Encoding.ASCII.GetBytes( strUserAgent );
MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
MD5.TransformBlock( abURL, 0, abURL.Length, abURL, 0 );
MD5.TransformBlock( abUA, 0, abUA.Length, abUA, 0 );
MD5.TransformBlock( abStatic, 0, abStatic.Length, abStatic, 0 );
MD5.TransformFinalBlock( abRandom, 0, abRandom.Length );
return String.Format( "{0}-{1}", strRandom,
BitConverter.ToString( MD5.Hash ).Replace( "-", "" ) );
}
/// <summary>
/// The main processor -- convert a decrypted atom tree to an encrypted one. See in-line comments.
/// </summary>
/// <returns>true if the operation was successful</returns>
public bool Process()
{
// Get the position of mdat before changes -- this will be necessary for chunk table offseting
long positionBefore = _root.Child("mdat").Position;
// Find the mp4a atom -- if not found, we're given a wrong file
Atoms mp4a = _root.Child("moov").Child("trak").Child("mdia").Child("minf").Child("stbl").Child("stsd").Child("mp4a");
if (mp4a == null || _outfile == null)
{
return(false);
}
Atoms sinf = mp4a.AppendAtom("sinf", null);
// Append an atom to sinf, containing the data "mp4a"
byte[] frma = Encoding.ASCII.GetBytes("mp4a");
sinf.AppendAtom("frma", frma);
// Append an atom to sinf, containing the data "itun" and 8 NULLs. Then append the schi atom to sinf
byte[] schm = new byte[12];
schm.Initialize();
Encoding.ASCII.GetBytes("itun", 0, 4, schm, 4);
sinf.AppendAtom("schm", schm);
Atoms schi = sinf.AppendAtom("schi", null);
// Grab the private key from the configuration file
byte[] privateKey = Utility.ToByteArray(ConfigurationSettings.AppSettings["privateKey"]);
// Append the user atom to schi
schi.AppendAtom("user", Utility.ToByteArray(ConfigurationSettings.AppSettings["user"]));
// Grab the key from the configuration file (obtained using iTunes' server) and append to schi
byte[] keyData = BitConverter.GetBytes(Convert.ToInt32(ConfigurationSettings.AppSettings["key"]));
Utility.Reverse(keyData);
schi.AppendAtom("key ", keyData);
// Grab the iviv and append to schi
byte[] ivivData = Utility.ToByteArray(ConfigurationSettings.AppSettings["iviv"]);
schi.AppendAtom("iviv", ivivData);
// Grab the righ and append to schi
byte[] righData = Utility.ToByteArray(ConfigurationSettings.AppSettings["righ"], 80);
schi.AppendAtom("righ", righData);
// Append the name atom (with the user's name, followed by NULLs) to schi
byte[] nameData = new byte[256];
Encoding.ASCII.GetBytes(ConfigurationSettings.AppSettings["name"]).CopyTo(nameData, 0);
string nameString = Encoding.ASCII.GetString(nameData);
schi.AppendAtom("name", nameData);
// Append the priv data to schi, and encrypt it
byte[] privData = Utility.ToByteArray(ConfigurationSettings.AppSettings["priv"], 440);
schi.AppendAtom("priv", privData);
byte[] privDataEncrypted = new byte[440];
privData.CopyTo(privDataEncrypted, 0);
// Hash the name and the iviv
MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
byte[] nameHashed = new byte[16];
MD5.TransformBlock(nameData, 0, nameString.IndexOf('\0'), nameHashed, 0);
MD5.TransformFinalBlock(ivivData, 0, ivivData.Length);
// Perform the encryption of the hash to get the new key and iv
Utility.RijndaelCrypt(privData, 0, privData.Length, privateKey, MD5.Hash, false);
if (Encoding.ASCII.GetString(privData, 0, 4) != "itun")
{
throw new Exception("The priv atom, the privateKey, or the name and iviv fields are invalid");
}
byte[] mdatKey = new byte[16];
Array.Copy(privData, 24, mdatKey, 0, 16);
byte[] mdatIV = new byte[16];
Array.Copy(privData, 48, mdatIV, 0, 16);
// Get the sample table
Atoms stbl = _root.Child("moov").Child("trak").Child("mdia").Child("minf").Child("stbl");
Atoms stsz = stbl.Child("stsz");
GetSampleTable(stsz.Data);
byte[] mdatData = _root.Child("mdat").Data;
int offset = 0;
// Encrypt all the chunks using the new key and iviv
for (int i = 0; i < _table.Length; ++i)
{
Utility.RijndaelCrypt(mdatData, offset, (int)_table[i], mdatKey, mdatIV, true);
offset += (int)_table[i];
}
// Change the type from m4pa to drms. Update chunk sizes (since we've appended quite a lot!)
mp4a.Type = "drms";
_root.GetAndUpdateSize();
// Update the chunk table (since the offsets shifted)
long positionAfter = _root.Child("mdat").Position;
Atoms stco = stbl.Child("stco");
UpdateChunkTable(stco.Data, (int)(positionAfter - positionBefore));
// Write the resulting data to the output file
byte[] data = _root.Bytes;
_output.Write(data, 0, data.Length);
return(true);
}