public bool VerifyContentHash(byte[] computedHash)
{
if (this._contentHash == null)
{
byte tag = this._binaryReader.ReadByte();
if (tag != 0x42)
{
throw new InvalidDataException();
}
IFileStreamHandler <IDictionary <string, object> > dataHandler =
this._handlerFactory.GetHandler <IDictionary <string, object> >(tag);
IDictionary <string, object> contentDirectory = dataHandler.Handle(this._binaryReader);
contentDirectory.TryGetValue("type", out var typeValue);
if ("metadata".Equals(typeValue))
{
contentDirectory.TryGetValue("file_md5", out var md5Value);
string md5String = md5Value as string;
if (md5String == null)
{
throw new InvalidDataException();
}
this._contentHash = md5String;
}
}
byte[] hashExpected = BytesUtils.HexStringToByteArray(this._contentHash);
return(BytesUtils.ByteArrayCompare(hashExpected, computedHash));
}
public FileCommunicationHandler(Communication communication)
{
_conversionHandler = new ConversionHandler();
_fileUtils = new FileUtils();
_communication = communication;
_fileStreamHandler = new FileStreamHandler(_fileUtils);
}
public FileMeta3 GetFileMeta()
{
byte metaTag = this._binaryReader.ReadByte();
if (metaTag != 0x42)
{
throw new InvalidDataException($"File {this._fileItem.Name} fails to extract meta");
}
IFileStreamHandler <IDictionary <string, object> > metaHandler =
this._handlerFactory.GetHandler <IDictionary <string, object> >(metaTag);
IDictionary <string, object> metaDict = metaHandler.Handle(this._binaryReader);
if (!(metaDict.ContainsKey("type") && "metadata".Equals(metaDict["type"])))
{
throw new InvalidDataException($"File {this._fileItem.Name} fails to extract meta");
}
return(FileMeta3.fromDictionary(metaDict));
}
public IEnumerable <byte[]> GetDataBlocks(IDecryptor decryptor)
{
byte[] buf = null;
while (true)
{
if (buf != null)
{
//yield return decryptor.DecryptBlock(buf, false);
yield return(buf);
}
byte tag = this._binaryReader.ReadByte();
if (tag != 0x42)
{
yield break;
}
IFileStreamHandler <IDictionary <string, object> > dataHandler =
this._handlerFactory.GetHandler <IDictionary <string, object> >(tag);
IDictionary <string, object> contentDirectory = dataHandler.Handle(this._binaryReader);
contentDirectory.TryGetValue("type", out var typeValue);
string typeValueString = typeValue as string;
if (!"data".Equals(typeValueString))
{
if ("metadata".Equals(typeValueString))
{
contentDirectory.TryGetValue("file_md5", out var md5Value);
string md5String = md5Value as string;
if (md5String != null)
{
this._contentHash = md5String;
}
}
yield break;
}
buf = (byte[])contentDirectory["data"];
}
}
public IDictionary <string, object> Handle(BinaryReader br)
{
IDictionary <string, object> returnDict = new Dictionary <string, object>();
//read key, 0x10 expected
Boolean hasNext = true;
while (hasNext)
{
byte keyTag = br.ReadByte();
switch (keyTag)
{
case 0x10:
IFileStreamHandler <string> stringHandler = this._factory.GetHandler <string>(keyTag);
string key = stringHandler.Handle(br);
//read value
byte valueTag = br.ReadByte();
IFileStreamHandler <object> valueHandler = this._factory.GetHandler <object>(valueTag);
if (valueHandler == null)
{
throw new InvalidDataException();
}
object value = valueHandler.Handle(br);
returnDict.Add(key, value);
break;
case 0x40:
hasNext = false;
continue;
default:
throw new InvalidDataException();
}
}
return(returnDict);
}
private void ParseFile()
{
var directory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
var path = $"{directory}\\Resources\\crypto\\encrypted_jpg_01.jpg";
string magic = "__CLOUDSYNC_ENC__";
byte[] magicBytes = Encoding.ASCII.GetBytes(magic);
using FileStream fs = new FileStream(path, FileMode.Open);
using BinaryReader br = new BinaryReader(fs);
byte[] value = br.ReadBytes(magicBytes.Length);
Console.WriteLine(ByteArrayCompare(magicBytes, value));
//check "__CLOUDSYNC_ENC__" Md5 hash
value = br.ReadBytes(32);
byte[] expectedMagicHash =
Encoding.ASCII.GetBytes(BytesUtils.ByteArrayToLowerHexString(Md5(magicBytes)));
Assert.AreEqual(expectedMagicHash, value);
//
HandlerFactory handlerFactory = new HandlerFactory();
StringHandler stringHandler = new StringHandler();
IntHandler intHandler = new IntHandler();
ByteSteamHandler byteSteamHandler = new ByteSteamHandler();
OrderedDictHandler dictHandler = new OrderedDictHandler(handlerFactory);
handlerFactory.AddHandler(stringHandler);
handlerFactory.AddHandler(dictHandler);
handlerFactory.AddHandler(intHandler);
handlerFactory.AddHandler(byteSteamHandler);
byte metaTag = br.ReadByte();
if (metaTag != 0x42)
{
throw new InvalidDataException();
}
IFileStreamHandler <IDictionary <string, object> > metaHandler =
handlerFactory.GetHandler <IDictionary <string, object> >(metaTag);
IDictionary <string, object> metaDict = metaHandler.Handle(br);
if (!(metaDict.ContainsKey("type") && "metadata".Equals(metaDict["type"])))
{
throw new InvalidDataException();
}
FileMeta3 fileMeta = FileMeta3.fromDictionary(metaDict);
Console.WriteLine(fileMeta);
AsymmetricKeyParameter akp = CryptoUtils.readPemPk(this.privateKey);
byte[] sessionKeyCharArray = CryptoUtils.RsaOaepDeciper(fileMeta.EncKey2, akp);
string computedSessionKeyHash = CryptoUtils.SaltedMd5(
fileMeta.SessionKeyHash.Substring(0, 10), sessionKeyCharArray);
if (!fileMeta.SessionKeyHash.Equals(computedSessionKeyHash))
{
throw new InvalidDataException("key is incorrect");
}
//decrypt content
byte[] sessionKey = BytesUtils.HexStringToByteArray(
Encoding.ASCII.GetString(sessionKeyCharArray));
Console.Write(sessionKey);
ParametersWithIV keys =
CryptoUtils.DeriveAESKeyParameters(sessionKey, null);
AesCbcCryptor decryptor =
new AesCbcCryptor(((KeyParameter)keys.Parameters).GetKey(), keys.GetIV());
List <byte[]> decryptedData = new List <byte[]>();
byte[] buf = null;
byte[] decBuf = null;
IDictionary <string, object> dataResult = null;
while (true)
{
byte dataTag = br.ReadByte();
if (dataTag == 0x40)
{
Console.WriteLine("come here");
}
if (dataTag != 0x42)
{
decBuf = decryptor.DecryptBlock(buf, true);
decryptedData.Add(decBuf);
break;
}
if (buf != null)
{
decBuf = decryptor.DecryptBlock(buf, false);
decryptedData.Add(decBuf);
}
IFileStreamHandler <IDictionary <string, object> > dataHandler =
handlerFactory.GetHandler <IDictionary <string, object> >(metaTag);
dataResult = dataHandler.Handle(br);
object typeValue = null;
dataResult.TryGetValue("type", out typeValue);
string typeValueString = typeValue as string;
if (!"data".Equals(typeValueString))
{
break;
}
buf = (byte[])dataResult["data"];
}
byte[] decData = CryptoUtils.Concat(decryptedData.ToArray());
File.WriteAllBytes("z:\\123.jpg.lz4", decData);
//last directory
//TODO validate dataResult["type"] == "metadata"
string fileMd5 = (string)dataResult["file_md5"];
Console.Write(fileMd5);
}
public void AddHandler(IFileStreamHandler <object> handler)
{
this._handlerDict[handler.SupportedTag] = handler;
}
