sub import_api_ex {
        my ( $lib, $sig ) = @_;
        my $key = join "_", map { uc } ( $lib, $sig );

        $api{$key} = Win32::API->new( $lib, $sig )
          unless exists $api{$key};

        return $api{$key};
    }

    sub define_struct {
        my ( $name, @params ) = @_;
        Win32::API::Struct->typedef( $name, @params );
    }

##</code><code>##

DWORD QueryUsersOnEncryptedFile(
  LPCWSTR lpFileName,                        // file name
  PENCRYPTION_CERTIFICATE_HASH_LIST *pUsers  // hash list
);

##</code><code>##

BEGIN {
    define_struct(
        'EFS_HASH_BLOB',
        qw/
          DWORD cbData;
          LPBYTE pbData;
          /
    );
    define_struct(
        'ENCRYPTION_CERTIFICATE_HASH',
        qw/
          DWORD cbTotalLength;
          void* pUserSid;
          LPEFS_HASH_BLOB pHash;
          LPWSTR lpDisplayInformation;
          /
    );
    define_struct(
        'ENCRYPTION_CERTIFICATE_HASH_LIST',
        qw/
          DWORD nCert_Hash;
          LPENCRYPTION_CERTIFICATE_HASH* pUsers;
          /
    );
}

##</code><code>##

sub query_users {
    my ( $self, $filename ) = @_;

    my $func = import_api_ex( 'advapi32', 'DWORD QueryUsersOnEncryptedFile(LPCWSTR lpFileName, LPENCRYPTION_CERTIFICATE_HASH_LIST* pUsers)'
    );
    die "Could not import API QueryUsersOnEncryptedFile: $!"
      unless defined $func;

}

##</code><code>##

Win32::API::parse_prototype: WARNING unknown parameter type 'LPENCRYPTION_CERTIFICATE_HASH_LIST*' at C:/Perl/site/lib/Wi
n32/API.pm line 248, <DATA> line 164.