ParagonIE_Sodium_Core_Ristretto255::scalarmult_ristretto255( string $n, string $p ): string

667    public static function scalarmult_ristretto255($n, $p)668    {669        if (self::strlen($n) !== 32) {670            throw new SodiumException('Scalar must be 32 bytes, ' . self::strlen($p) . ' given.');671        }672        if (self::strlen($p) !== 32) {673            throw new SodiumException('Point must be 32 bytes, ' . self::strlen($p) . ' given.');674        }675        $result = self::ristretto255_frombytes($p);676        if ($result['res'] !== 0) {677            throw new SodiumException('Could not multiply points');678        }679        $P = $result['h'];680 681        $t = self::stringToIntArray($n);682        $t[31] &= 0x7f;683        $Q = self::ge_scalarmult(self::intArrayToString($t), $P);684        $q = self::ristretto255_p3_tobytes($Q);685        if (ParagonIE_Sodium_Compat::is_zero($q)) {686            throw new SodiumException('An unknown error has occurred');687        }688        return $q;689    }