DIGEST_AUTHENTICATION.md

Overview

Digest access authentication is an HTTP method that allows a web server to verify a user’s credentials (such as username and password) before granting access to protected resources, like online banking data.

Instead of sending credentials in plain form, it applies a cryptographic hash function to the username and password before transmission, improving security.

In contrast, Basic access authentication only uses Base64 encoding, which is easily reversible and does not provide real security unless combined with TLS encryption.

Example

#include <regex>
#include <memory>
#include <string>
#include <cstdlib>
#include <restbed>

using namespace std;
using namespace restbed;

string build_authenticate_header( void )
{
    string header = "Digest realm=\"Restbed\",";
    header += "algorithm=\"MD5\",";
    header += "stale=false,";
    header += "opaque=\"0000000000000000\",";
    header += "nonce=\"Ny8yLzIwMDIgMzoyNjoyNCBQTQ\"";

    return header;
}

void authentication_handler( const shared_ptr< Session > session,
                             const function< void ( const shared_ptr< Session > ) >& callback )
{
    const auto request = session->get_request( );

    auto authorisation = request->get_header( "Authorization" );

    bool authorised = regex_match( authorisation, regex( ".*response=\"02863beb15feb659dfe4703d610d1b73\".*" ) );

    if ( authorised )
    {
        callback( session );
    }
    else
    {
        session->close( UNAUTHORIZED, { { "WWW-Authenticate", build_authenticate_header( ) } } );
    }
}

void get_method_handler( const shared_ptr< Session > session )
{
    return session->close( OK, "Password Protected Hello, World!", { { "Content-Length", "32" } } );
}

int main( const int, const char** )
{
    auto resource = make_shared< Resource >( );
    resource->set_path( "/resource" );
    resource->set_method_handler( "GET", get_method_handler );

    auto settings = make_shared< Settings >( );
    settings->set_port( 1984 );
    settings->set_default_header( "Connection", "close" );

    Service service;
    service.publish( resource );
    service.set_authentication_handler( authentication_handler );

    service.start( settings );

    return EXIT_SUCCESS;
}

Build

$ clang++ -std=c++20 -o example example.cpp -l restbed

Execution

$export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib $ ./example

$ curl -w'\n' -v --digest -XGET 'http://Corvusoft:Glasgow@localhost:1984/resource'