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Welcome to the CryptoZoo!

A place where state separating proofs (SSPs) live.

State-separating proofs SSPs are a style to define cryptographic properties and in particular to structure their proofs. The CryptoZoo proof viewer allows you to engage with proofs interactively, find relevant information quickly, hide information that isn't interesting to you at the moment and much more.

Want to check out how it works? Here are three nice examples!

• IND-CPA: This is a warm-up example if you are not so familiar with SSPs or cryptographic definitions as a whole. It shows that two security notions for symmetric encryption are equivalent.

• GGM PRF-from-PRG: This is a (constant-depth) version of a famous proof by Goldreich, Goldwasser and Micali (GGM) who show that pseudorandom generators (PRGs) imply stream ciphers, a.k.a. pseudorandom functions (PRFs), by stacking PRGs in a tree-like fashion. In SSP-style fashion, the proof is very short and neat (for a constant-depth tree) and thus a nice intermediate example. It is also a very clean example of a hybrid proof. .

• Garbling Security of Yao's Protocol: This is a proof of Yao's famous garbling scheme, which is a core building block for secure multi-party computation. This is the most advanced example and involves a hybrid over the depth and width of a circuit. We visualize the state-separating proof of Yao's garbling scheme by Brzuska and Oechsner.

SSP Ressources

For a nice introduction to SSPs, Lúcás Meier wrote a overview blogpost that is highly recommended. For a formal and rigorous introduction to SSPs you can check out the BDFKK paper who also have a nice introduction to hybrid proofs in Appendix B.