HMAC errors (char to byte conversion)

[Karol Krizka]

Hi,
I am new to using this library. I am only using it because I want my
program to hash something using HMAC. I am triing to figure it out.
Here's my code:

#include <cryptopp/md5.h>
#include <cryptopp/filters.h>
#include <cryptopp/files.h>
#include <cryptopp/hex.h>
#include
<cryptopp/hmac.h>                                                                      
                                                #include <iostream>
                                                                                       
                                  using namespace CryptoPP;
using namespace std;
                                                                                       
                                      int main( int argc, char** argv ) {
        char* pbKey="key";
        int nKeyLen=sizeof(pbKey);
        char* pbOutputBuffer;
        char* pbData="Karol";
        int nDataLen=sizeof(pbData);
        HMAC<MD5 >(pbKey,nKeyLen).CalculateDigest(pbOutputBuffer,pbData,
nDataLen);
        cout << "Digest: " << pbOutputBuffer << endl;
        return 0;
}

When I compile it with gcc 3.3.2, I get the following errors:
g++ main.cpp -lcryptopp -o test
main.cpp: In function `int main(int, char**)':
main.cpp:18: error: invalid conversion from `const char*' to `const
byte*'
main.cpp:18: error:   initializing argument 1 of
`CryptoPP::HMAC<T>::HMAC(const
   byte*, unsigned int) [with T = CryptoPP::MD5]'
main.cpp:18: error: invalid conversion from `char*' to `byte*'
main.cpp:18: error:   initializing argument 1 of `virtual void
   CryptoPP::HashTransformation::CalculateDigest(byte*, const byte*,
unsigned
   int)'
main.cpp:18: error: invalid conversion from `const char*' to `const
byte*'
main.cpp:18: error:   initializing argument 2 of `virtual void
   CryptoPP::HashTransformation::CalculateDigest(byte*, const byte*,
unsigned
   int)'

I have searched for some time, and the "documentation" that this thing
has didn't answer my question or fix my errors.
-- 
Cheers
--RoadkillBunny