Case 1:17-cv-02989-AT Document 579 Filed 08/15/19 Page 40 of 153 at 95.) The key to the NAS recommendation is that paper ballots are required for such audits. The report recommended that voting machines that do not produce paper audit trails “be removed from service as soon as possible” and that “[a]ll local, state, and federal elections should be conducted using human-readable paper ballots by the 2020 presidential election.” (Id. at 80.) The NAS report also noted several cybersecurity risks regarding electronic pollbooks and voter registration databases. It detailed concerns about “unauthorized access to or manipulation of the registrant list” because voter registration databases are “often connected, directly or indirectly, to the Internet or state computer networks.” (Doc. 285-1, Ex. 1 at 57.) As an example of the vulnerability of electronic voter databases, the report listed the server error that left 6.5 million voter records in Georgia exposed for six months in 2016-17. (Id. at 58.) The NAS report listed a number of ways in which cyberattacks on electronic voter registration data or e-pollbooks could disrupt elections: 1) by altering voter registration databases used to generate pollbooks; 2) by altering the record of which eligible voters have actually voted; and 3) by a “denial-of-service” attack, which would shut done voting altogether. (Id. at 72.) Thus, the NAS report recommends that “[j]urisdictions that use electronic pollbooks should have backup plans in place to provide access to current voter registration lists in the event of any disruption.” (Id.) Dr. Halderman most recently testified before the U.S. Senate Select Committee on Intelligence that prominently featured his testimony in its report, 40