As millions of Americans vote in today’s U.S. midterms, most will use paper ballots, which are protected by strict chain-of-custody protocols and, in some cases, statistical audits. You may wonder why we still use paper for our elections and voting systems when tasks like banking, tax filing, and document signing have moved away from paper-based legacy systems and become fully electronic. The short answer: security. That may come as a surprise to some. After all, cryptography and other security advancements have enabled secure electronic systems for many applications. In fact, cryptography can be used to provide two essential safeguards in elections: keeping (1) individual votes secret while (2) making the final tally independently verifiable. This is exactly the approach of cryptographic protocols like Helios and ElectionGuard. However, Helios intentionally targets lower-risk and lower-coercion settings rather than high-stakes public elections. ElectionGuard, by contrast, is intended for public elections, but not as a replacement for a paper-based system; it is used as a cryptographic layer integrated with traditional voting infrastructure. In this blog post, we’ll explain how cryptographic techniques can help protect ballot secrecy and prevent manipulation in electronic voting systems, and explore the limitations of these systems. Although cryptography can strengthen election verifiability and have other strong security properties, it cannot fully replace the security and trust of existing paper ballot systems in general elections. The challenges of electronic voting The National Academy of Sciences’ excellent 2018 report on election security concludes that electronic ballot return (also known as online voting or internet voting) should not be used in general elections, since “no known technology guarantees the secrecy, security, and verifiability of a marked ballot transmitted over the Internet.” The difficulty of this problem makes sense when you consider the st

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