public static function fromAlgorithmIdentifier(PRFAlgorithmIdentifier $algo): PRF
    {
        $oid = $algo->oid();
        if (array_key_exists($oid, self::MAP_HASH_OID_TO_CLASS)) {
            $cls = self::MAP_HASH_OID_TO_CLASS[$oid];
            return new $cls();
        }
        throw new \UnexpectedValueException(
            "PRF algorithm " . $algo->oid() . " not supported.");
    }