Debug Assertion Failed- Invalid Null Pointer

[MsNora]

Hello guys. Recently, I had run a project/solution in Microsoft Visual C++ 2010 Express. The build was successful. But when I try to debug the solution, an error pop up.It says..

"Debug Assertion Failed!
Program: ...
File: c:\program files\Microsoft visual studio 10.0\vc\include\istream
Line:990
Expression: invalid null pointer...."

This is the output from the call stack. The line in the code that I've bold is the one that pointed by the call stack. I hope any of you guys can help me.

> attestation1.exe!std::operator>><char,std::char_traits<char> >(std::basic_istream<char,std::char_traits<char> > && _Istr, char * _Str) Line 1020 + 0x3 bytes

basic_istream<_Elem, _Traits> && _Istr, _Elem *_Str)
	{	// extract NTBS
	_DEBUG_POINTER(_Str);
	typedef basic_istream<_Elem, _Traits> _Myis;
	typedef ctype<_Elem> _Ctype;
	ios_base::iostate _State = ios_base::goodbit;
	_Elem *_Str0 = _Str;
	const typename _Myis::sentry _Ok(_Istr);

	if (_Ok)
		{	// state okay, extract characters
		const _Ctype& _Ctype_fac = _USE(_Istr.getloc(), _Ctype);

		_TRY_IO_BEGIN
		streamsize _Count = 0 < _Istr.width() ? _Istr.width() : INT_MAX;
		typename _Myis::int_type _Meta = _Istr.rdbuf()->sgetc();
		_Elem _Ch;
		for (; 0 < --_Count; _Meta = _Istr.rdbuf()->snextc())
			if (_Traits::eq_int_type(_Traits::eof(), _Meta))
				{	// end of file, quit
				_State |= ios_base::eofbit;
				break;
				}
			else if (_Ctype_fac.is(_Ctype::space,
				_Ch = _Traits::to_char_type(_Meta))
					|| _Ch == _Elem())
				break;	// whitespace or nul, quit
			else
				*_Str++ = _Traits::to_char_type(_Meta);	// add it to string
		_CATCH_IO_(_Istr)
		}

	*_Str = _Elem();	// add terminating null character
	_Istr.width(0);
	_Istr.setstate(_Str == _Str0 ? _State | ios_base::failbit : _State);
	return (_Istr);
	}

> attestation1.exe!std::operator>><char,std::char_traits<char> >(std::basic_istream<char,std::char_traits<char> > & _Istr, char * _Str) Line 1085 + 0x16 bytes

basic_istream<_Elem, _Traits>& _Istr, _Elem *_Str)
	{	// extract NTBS
	return (_STD move(_Istr) >> _Str);
	}

> attestation1.exe!operator>>(std::basic_istream<char,std::char_traits<char> > & s, Big & x) Line 276 + 0x13 bytes

istream& operator>>(istream& s, Big& x)
{ 
  miracl *mip=get_mip();
  if (mip->IOBASE>60) 
  {
     s.sync(); 
     s.getline(mip->IOBUFF,mip->IOBSIZ);
  }
  else s >> mip->IOBUFF;
  if (s.eof() || s.bad()) 
  {   
      zero(x.fn); 
      return s; 
  }
  cinstr(x.fn,mip->IOBUFF); 
  return s;
}

> attestation1.exe!encrypt() Line 454 + 0x1a bytes

int encrypt()
{
    miracl *mip=mirsys(16,0);   // thread-safe ready. (32,0) for 1024 bit p
    ifstream common("common.ibe");
    ifstream plaintext;
    ofstream key_file,ciphertext;
    ECn U,P,Ppub,Qid,infinity;
    ZZn2 gid,cube,w;
    char key[HASH_LEN],pad[HASH_LEN],rho[HASH_LEN],V[HASH_LEN],W[HASH_LEN];
    char ifname[100],ofname[100],ch,iv[16];
    Big p,q,r,x,y,cof;
    int i,bits;
    long seed;
    aes a;

    cout << "Enter your 9 digit number  = ";
    cin >> seed;
    irand(seed);

// ENCRYPT

    common >> bits;
    mip->IOBASE=16;
    common >> p >> q;

    cof=(p+1)/q;

    common >> x >> y;
    EBrick B(x,y,(Big)0,(Big)1,p,8,QBITS);   // precomputation based on fixed P, 8-bit window

#ifdef AFFINE
    ecurve(0,1,p,MR_AFFINE);
#endif
#ifdef PROJECTIVE
    ecurve(0,1,p,MR_PROJECTIVE);
#endif

    P.set(x,y);

    common >> x >> y;
    Ppub.set(x,y);

    common >> x >> y;
    cube.set(x,y);

    char id[1000];
    cout << "Enter your correspondents email address (lower case)" << endl;
    cin.get();
    cin.getline(id,1000);

    mip->IOBASE=10;
    Qid=map_to_point(id);

// This can be done before we know the message to encrypt

    if (!ecap(Ppub,Qid,q,cube,gid))      // ** swap argument order
    {                                    // Qid must be second
        cout << "Bad Parameters" << endl;
        exit(0);
    } 

//
// prepare to encrypt file with random session key
//

    for (i=0;i<HASH_LEN;i++) key[i]=(char)brand();
    for (i=0;i<16;i++) iv[i]=i; // set CFB IV

    aes_init(&a,MR_CFB1,16,key,iv);
    
// figure out where input is coming from

    cout << "Text file to be encoded = " ;
    cin >> ifname;

   /* set up input file */
    strcpy(ofname,ifname);
    strip(ofname);
    strcat(ofname,".ibe");
    plaintext.open(ifname,ios::in); 
    if (!plaintext)
    {
        cout << "Unable to open file " << ifname << "\n";
        return 0;
    }
    cout << "encoding message\n";
    ciphertext.open(ofname,ios::binary|ios::out);

// now encrypt the plaintext file

    forever
    { // encrypt input ..
        plaintext.get(ch);
        if (plaintext.eof()) break;
        aes_encrypt(&a,&ch);
        ciphertext << ch;
    }

    aes_end(&a);

//
// Now IBE encrypt the session key
//

    for (i=0;i<HASH_LEN;i++) rho[i]=(char)brand();
//cout << "rho= " << rho << endl;
//cout << "key= " << key << endl;
    r=H3(rho,key)%q;

    B.mul(r,x,y);       // U=r*P
    U.set(x,y);

    w=pow(gid,r);         

//cout << "r= " << r << endl;
//cout << "w= " << w << endl;
    
    H2(w,pad);
//cout << "pad1= " << pad << endl;    
    for (i=0;i<HASH_LEN;i++) 
    {
        V[i]=rho[i]^pad[i];
        pad[i]=0;
    }

//cout << "rho= " << rho << endl;

    H4(rho,rho);


    for (i=0;i<HASH_LEN;i++) 
    {
        W[i]=key[i]^rho[i];
        rho[i]=0;
    }

    strip(ofname);
    strcat(ofname,".key");
    mip->IOBASE=16;
    key_file.open(ofname);
    U.get(x,y);
    key_file << y << endl;
    x=from_binary(HASH_LEN,V);      // output bit strings in handy Big format
    key_file << x << endl;
    x=from_binary(HASH_LEN,W);
    key_file << x << endl;

	return 0;
}

> attestation1.exe!main(int argc, char * * argv) Line 889

int _tmain(int argc, _TCHAR* argv[])
{
	nonce_TV();
	encrypt();
	connection();

	return 0;

}