TWC: Small: Better Security for Efficient Secret-Key Cryptography

当今的密码学主要依赖于密钥密码学，即通信各方使用对攻击者隐藏的共享密钥来安全地加密和/或验证数据的设置。密钥加密基于标准化的高效算法，称为加密原语，如块密码和散列函数。它们作为所谓的操作模式的构建块，为加密和身份验证实现强大的安全目标的加密算法，并且比公钥快几个数量级。该项目解决了当前对称密钥密码学的两个缺点，即现有分组密码缺乏可证明的安全性，以及由于现有原语实现中的固定参数而缺乏灵活性。该项目开发了新的可证明安全的密码，具有强大的安全保证，假设攻击者只有对简单底层组件的黑盒访问。研究者探索了一种新的形式模型，该模型捕获了加密攻击中本地计算和依赖密钥的访问之间的权衡，并在这种新观点下开发了具有改进安全性的新操作模式。该项目将对社会产生广泛的影响，为用于现代通信和商业安全的密钥密码学的发展奠定基础。

Present-day cryptography crucially relies on secret-key cryptography, the setting where communicating parties use a shared secret key, hidden to the attacker, to securely encrypt and/or authenticate data. Secret-key cryptography is based on standardized efficient algorithms known as cryptographic primitives, such as block ciphers and hash functions. These act as building blocks for so-called modes of operations, cryptographic algorithms achieving strong security goals for encryption and authentication, and which are orders of magnitude faster than public-key ones. This project addresses the two shortcomings of current symmetric key cryptography, namely the lack of provable security for existing block ciphers and the lack of flexibility due to fixed parameters in existing implementations of primitives. The project develops new provably secure ciphers with strong security guarantees under the assumption that an attacker only has black box access to a simple underlying component. The investigator explores a new formal model that captures tradeoffs between local computation and key-dependent access in cryptographic attacks, and develops new modes of operation with improved security under this new viewpoint. The project will have broad impact on society by laying the foundations for the development of secret key cryptography which is used to secure modern communications and commerce.