some problem in RSA file encryption using crypto++ 5.2.1

[Khurram Shahzad]

hi all

i use crypto 5.2.1 in my project using the envoirnment MSVC 2003 v7.1. the 
thing i try is i encrypt the small file using RSA public key, with finction 
used for string encryption for RSA... signature like:


bool RSAEncryptFile(char *pubFilename, char *seed, const char *in, const char 
*ciphertext)
{
    FileSource pubFile(pubFilename, true, new HexDecoder);
    RSAES_OAEP_SHA_Encryptor pub(pubFile);

    RandomPool randPool;
    randPool.Put((byte *)seed, strlen(seed));
    
    FileSource fE( in, true, new PK_EncryptorFilter(randPool, pub, 
                new HexEncoder(new FileSink(ciphertext))) );

    return true;
}

 this function RSAEncryptFile takes public key in "char *pubFilename" 
parameter, input file used for encryption in "const char *in" parameter and 
place the encrypted file in "const char *ciphertext" parameter.

it works well on small file of size 56 bytes text file... but when i give file 
of size 32MB then my program crash with this exception:

Unhandled exception at 0x7c4ea4e1 in Cpt.exe: Microsoft C++ exception: 
CryptoPP::InvalidArgument @ 0x0012ed94.

and debugger points to file pubkey.cpp line 121:

   SecByteBlock paddedBlock(PaddedBlockByteLength());

could anyone help me in this particular senario, may be my function calling for 
file encrytion is wronge , or some thing else is to be try..
thanks..

KHURRAM SHAHZAD