Use DLL when no C source code

Question

I have a special proprietary type files, lets say .KTV
There are several layers to the KTV file format:
1. XML
2.ZLib Deflate compresion
3.Rijndael AES encryption
well, I need to read the XML text. I know that Java already includes Deflate and AES algorithms so I could write an extractor.
but,
I was given a DLL file which is used in a CPP project just for the same purpose, and I assume i can use it to obtain XML output from KTV files. The big problem is that I have no idea of the methods, or their signatures the DLL files contains.
Has anyone any ideas there should I start my investigation using the DLL for this purpose?

Answer 1

I found this in a header file .h which is included in the .CPP file which has the method I want to tuse:
basically I need to use only the ReadFile routine.
Is is this a problem, that the method is inside a CPP class and is not standalone?
Once I have this header file how should I implement the Java class?
class KTV_API KTVFile
public:
     enum Modes
          modeRead          = 0x00,
          modeWrite          = 0x01,
          modeNoHeader     = 0x02,
          modeNoCompress     = 0x40,
          modeNoEncrypt     = 0x80,
     KTVFile();
     ~KTVFile();
     bool Open(const _TCHAR* filename, int openMode);
     bool Close();
     unsigned int Read(void* buffer, unsigned int len);
     unsigned int Write(const void* buffer, unsigned int len);
private:
     enum Masks
          maskCompressEncrypt     = 0xC0,
          maskVersion               = 0x3F,
     bool     IsWriting();
     bool     IsCompressionEnabled();
     bool     IsEncryptionEnabled();
     bool     IsHeaderEnabled();
     bool     WriteFile(const void* buffer, unsigned int len);
     int          ReadFile(void* buffer, unsigned int len);
     bool     Deflate(const unsigned char* buffer, unsigned int len, bool isFinal = false);
     int          Inflate(unsigned char* buffer, unsigned int len, bool isFinal = false);
     bool     Encrypt(const void* buffer, unsigned int len);
     int          Decrypt(void* buffer, unsigned int len);
     int                    m_openMode;
     FILE*               m_pFile;
     unsigned char*     m_inbuf;
     unsigned char*  m_inbuf_start;
     unsigned char*     m_inbuf_end;
     unsigned char*     m_zbuf;
     unsigned char*     m_cryptbuf;
     z_stream          m_Zstream;
     CRijndael*          m_pRijndael;
};