PHP Basic Authentication Header

basic-authentication.php

<?php 

$realm = 'My Realm Name';

//user => password
$users = [ 'user1' => 'pass1', 'user2' => 'pass2' ];

$authenticated = !empty( $_SERVER[ 'PHP_AUTH_DIGEST' ] );

if ( $authenticated && !( $data = http_digest_parse( $_SERVER[ 'PHP_AUTH_DIGEST' ] ) ) || !isset( $users[ $data[ 'username' ] ] ) ) {
    $authenticated = false;
} else {
        // generate the valid response
        $A1 = md5( $data[ 'username' ] . ':' . $realm . ':' . $users[ $data[ 'username' ] ] );
        $A2 = md5( $_SERVER[ 'REQUEST_METHOD' ] . ':' . $data[ 'uri' ] );
        $valid_response = md5( $A1 . ':' . $data[ 'nonce' ] . ':' . $data[ 'nc' ] . ':' . $data[ 'cnonce' ] . ':' . $data[ 'qop' ] . ':' . $A2 );

        if ( $data[ 'response' ] != $valid_response ) $authenticated = false;
}


if ( !$authenticated ) {
    header( 'HTTP/1.1 401 Unauthorized' );
    header( 'WWW-Authenticate: Digest realm="' . $realm . '",qop="auth",nonce="' . uniqid() . '",opaque="' . md5( $realm ) . '"' );
    die( 'Text to send if user hits Cancel button' );
}

// Whatever is here, will shown if user is authenticated.