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1/ I dove into a new crypto protocol, ZEXE. It’s an exciting, if early, spec for a private distributed execution environment capable of expressive applications. The paper is a collaboration of researchers from UC Berkeley, Johns Hopkins, Zcash and Cornell. eprint.iacr.org/2018/962.pdf
2/ ZEXE extends the Zerocash Protocol underlying Zcash. Zcash makes use of zk-SNARKs, which are cryptographic constructions that allow statements to be made and verified without revealing why they are true.
3/ In Zcash, the system is constrained and optimized around simple value transfers. The proofs verify statements about individual coins and their corresponding serial numbers. ZEXE extends this to allow arbitrary functions that operate on records, which represent value or data.
4/ Users invoke functions creating processes, which is how progress is made. Processes need to share a ledger without violating the integrity of other processes. Allowing no interprocess communication limits functionality, but allowing too much creates an unreliable system.
5/ ZEXE provides us with a framework known as a nano-kernel and specifies rules for how records can be created, accessed and modified. It is very low level, and will need developer friendly libraries and frameworks to be built on top. 
6/ Verifying arbitrary computations on the blockchain can be quite expensive, so the researchers propose using recursive proofs. Proofs of proofs, in other words, that can be verified very quickly even if the underlying becomes moderately complex.
7/ While verifying these proofs is easy, creating them is computationally intensive. The researchers explore ways to delegate this task to worker computers, which may be untrusted. It’s possible to offload the creation of the proofs without risking funds.
8/ The team has produced a proof-of-concept with some code, but more details around consensus and incentive mechanisms are needed before we’d have a complete usable system. I am not aware of any timeline yet but this is a project to keep an eye on!
