Visual C++ :: Crypt Input File Using ECIES

I am trying to make a basic crypting program, you simply input a file and it's crypted using ECIES.

So I use cryptopp, ( see the function : [URL] .....).

So I thought I just needed to open the files and crypt the content like that :

Code:
file = "lorem.txt"
std::ifstream if1s(file);
std::string content((std::istreambuf_iterator<char>(if1s)), std::istreambuf_iterator<char>());
if1s.close();

[Code] ....

Encrypt is a custom made function to make encryption simplier here is the header :

Code:
string encrypt(string message);

This works pretty well on text files but when I try to crypt a 1 mb image, the output is 0.5 kb which obviously can't be right, so I wonder if there is some specific way to crypt some files.