Numerous institutions, such as companies, universities, or non-governmental organizations, employ Internet voting for remote elections. Since the main purpose of an election is to determine the voters' will, it is fundamentally important to ensure that the final election result correctly reflects the voters' votes. To this end, modern secure Internet voting schemes aim for what is called end-to-end verifiability. This fundamental security property ensures that the correctness of the final result can be verified, even if some of the computers or parties involved are malfunctioning or corrupted. A standard component in this approach is so called cast-as-intended verifiability which enables individual voters to verify that the ballots cast on their behalf contain their intended choices. Numerous approaches for cast-as-intended verifiability have been proposed in the literature, some of which have also been employed in real-life Internet elections. One of the well established approaches for cast-as-intended verifiability is to employ a second device which can be used by voters to audit their submitted ballots. This approach offers several advantages - including support for flexible ballot/election types and intuitive user experience - and it has been used in real-life elections, for instance in Estonia. In this work, we improve the existing solutions for cast-as-intended verifiability based on the use of a second device. We propose a solution which, while preserving the advantageous practical properties sketched above, provides tighter security guarantees. Our method does not increase the risk of vote-selling when compared to the underlying voting protocol being augmented and, to achieve this, it requires only comparatively weak trust assumptions. It can be combined with various voting protocols, including commitment-based systems offering everlasting privacy.

翻译：众多机构，例如公司、大学或非政府组织，均采用互联网投票进行远程选举。由于选举的主要目的是确定选民意愿，确保最终选举结果正确反映选民投票至关重要。为此，现代安全的互联网投票方案旨在实现所谓的端到端可验证性。这一基本安全属性确保，即使部分参与的计算机或方出现故障或受损，最终结果的正确性仍可被验证。该方案中的标准组件是所谓的“按预期投出”可验证性，它使个别选民能够验证代表其提交的选票是否包含其预期选择。文献中已提出多种实现“按预期投出”可验证性的方法，其中一些已在现实互联网选举中应用。一个成熟的方法是使用辅助设备，供选民审计其已提交的选票。该方法具有多项优势——包括支持灵活的选票/选举类型及直观的用户体验——并已在现实选举（例如爱沙尼亚）中使用。在本工作中，我们改进了基于辅助设备使用的现有“按预期投出”可验证性方案。我们提出一种解决方案，在保留上述有利实用特性的同时，提供更严格的安全保障。与所增强的底层投票协议相比，我们的方法不会增加投票出售风险，且为实现此目标仅需相对较弱的信任假设。该方法可与多种投票协议结合，包括提供永恒隐私的承诺制系统。