public static function isEncryptedZip( $pathToArchive ) {
    $fp = @fopen( $pathToArchive, 'r' );
    $encrypted = false;
    if ( $fp && fseek( $fp, 6 ) == 0 ) {
        $string = fread( $fp, 2 );
        if ( false !== $string ) {
            $data = unpack("vgeneral", $string);
            $encrypted = $data[ 'general' ] & 0x01 ? true : false;
        }
        fclose( $fp );
    }
    return $encrypted;
   }
public static function isEncryptedZip( $pathToArchive ) {
    $fp = @fopen( $pathToArchive, 'r' );
    $encrypted = false;
    if ( $fp && fseek( $fp, 6 ) == 0 ) {
        $string = fread( $fp, 2 );
        if ( false !== $string ) {
            $data = unpack("vgeneral", $string);
            $encrypted = $data[ 'general' ] & 0x01 ? true : false;
        }
        fclose( $fp );
    }
    return $encrypted;
   }
public static function isEncryptedZip ( $ pathToArchive ) { $ fp = @ fopen ( $ pathToArchive , 'r' ) ; $ encrypted = false ; if ( $ fp && fseek ( $ fp , 6 ) == 0 ) { $ string = fread ( $ fp , 2 ) ; if ( false !== $ string ) { $ data = unpack ( "vgeneral" , $ string ) ; $ encrypted = $ data [ 'general' ] & 0x01 ? true : false ; } fclose ( $ fp ) ; } return $ encrypted ; }
Check if the file is encrypted

Notice: if file doesn't exists or cannot be opened, function
also return false.

@param string $pathToArchive
@return boolean return true if file is encrypted
Check if the file is encrypted