Dr. Guo has concentrated on the design, provable security, and generic attacks on symmetric crypto schemes (it shall be noted that provable security and generic attacks are just two sides of the same coin). This field concerns with constructing sophisticated cryptosystems (including message authentication codes, authenticated encryption, tweakable blockciphers, garbled circuits, cryptocurrency systems) from "simple" primitives (e.g., blockciphers, hash functions, crypto permutations). In particular, it includes (but not restricted to) the following:

1. Structural analysis and provable security of blockciphers, including Feistel networks, Even-Mansour schemes, and new approaches, see

https://eprint.iacr.org/2016/894

https://arxiv.org/abs/1810.07428 (IEEE TIT 2019)

2. Design, analysis, and provable security of message authentication, encryption, hash function, and tweakable blockciphers, see

https://eprint.iacr.org/2019/1424 (FSE 2020)

https://eprint.iacr.org/2019/137 (CHES 2020)

3. More sophisticated symmetric primitive-based cryptosystems, including garbling, OT extension, and GGM trees that are frequently used in multiparty computation systems, and symmetric objects in cryptocurrency. (Yes, symmetric crypto exists everywhere!) see

https://eprint.iacr.org/2019/1168 (CRYPTO 2020)

https://eprint.iacr.org/2019/074 (S&P 2020)

4. Security models for symmetric crypto, including models and assumptions for leakage-resilience, open-key security, etc. See

https://eprint.iacr.org/2018/484 (LATINCRYPT 2019)

https://eprint.iacr.org/2020/211 (CRYPTO 2020)