更新容忍和可撤销的密码备份（扩展版）
Update-tolerant and Revocable Password Backup (Extended Version)
摘要：
用户几乎不可能为他们的在线账户记住大量强大和个性化的密码。一个解决方案是随机生成密码并存储它们。然而，存储密码而不是记住它们会带来丢失的风险，例如，在存储密码的设备损坏、丢失或被盗的情况下。这使得创建密码备份不可或缺。然而，将这些备份放置在安全的位置以保护它们免受丢失和未经授权的访问，并同时保持它们最新，这在实践中是一个未解决的问题。我们提出了PASCO，密码的备份解决方案，解决了这一挑战。PASCO备份无需更新，即使用户的密码组合已更改。PASCO备份可以在没有物理访问权限的情况下撤销。这可以防止密码泄漏，即使用户失去对备份的控制。此外，我们展示了如何扩展PASCO，使一个完全可控的紧急访问。它允许用户在紧急情况下让其他人访问他的密码。我们还提出了一个安全评估和PASCO的实施。
英文摘要：
It is practically impossible for users to memorize a large portfolio of strong and individual passwords for their online accounts. A solution is to generate passwords randomly and store them. Yet, storing passwords instead of memorizing them bears the risk of loss, e.g., in situations where the device on which the passwords are stored is damaged, lost, or stolen. This makes the creation of backups of the passwords indispensable. However, placing such backups at secure locations to protect them as well from loss and unauthorized access and keeping them up-to-date at the same time is an unsolved problem in practice. We present PASCO, a backup solution for passwords that solves this challenge. PASCO backups need not to be updated, even when the user's password portfolio is changed. PASCO backups can be revoked without having physical access to them. This prevents password leakage, even when a user loses control over a backup. Additionally, we show how to extend PASCO to enable a fully controllable emergency access. It allows a user to give someone else access to his passwords in urgent situations. We also present a security evaluation and an implementation of PASCO.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
