Source

File: wp-admin/includes/file.php

function wp_trusted_keys() {
	$trusted_keys = array();

	if ( time() < 1617235200 ) {
		// WordPress.org Key #1 - This key is only valid before April 1st, 2021.
		$trusted_keys[] = 'fRPyrxb/MvVLbdsYi+OOEv4xc+Eqpsj+kkAS6gNOkI0=';
	}

	// TODO: Add key #2 with longer expiration.

	/**
	 * Filter the valid signing keys used to verify the contents of files.
	 *
	 * @since 5.2.0
	 *
	 * @param string[] $trusted_keys The trusted keys that may sign packages.
	 */
	return apply_filters( 'wp_trusted_keys', $trusted_keys );
}