Bug Fix: user_login doesn't exist in POST values.

In version 3.5.1 the user_value index does not exist in the POST value so line 171 in enforce-strong-password.php is throwing an error. If you change the function to use $current_user->user_login instead, the issue should be resolved.

The function would look like this with the change described:

function strong_password_enforcement( $errors ) {
	extract( $this->get_options() );
	get_currentuserinfo();

	if ( !$errors->get_error_data("pass")
	  && $_POST["pass1"]
	  && $this->get_password_strength( $_POST["pass1"], $current_user->user_login ) < $minimal_required_strength ) {
		$errors->add(
			'pass',
			sprintf(
				__( 'Please enter a %sstronger%s password to ensure your and this blog\'s security.', self::txd ),
				"<strong>",
				"</strong>"
			)
		);
	}
	return $errors;
}

http://ww.wp.xz.cn/extend/plugins/enforce-strong-password/