This Rust crate is an implementation of the WACC VM specification that is a part of the provenance specifications. It extends a standard web assembly VM with the set of data manipulation and cryptographic operations found in the WACC VM specification. Please see the specification Appendix for a full discussion of the motivation and design principles behind the this implementation.
In general, the WACC VM is designed to be a way to describe data validation scripts similar to the way Bitcoin scripts work when validating a Bitcoin transaction. WACC VM scripts operate on fields in a virtual key-value store with strings as keys. No data is manipulated directly by the WACC scripts, they simply push and pop keys to the virtual stack and then execute cryptographic operations on the values associated with the keys on the stack and then do logic tests on the results.
WACC VM scripts are designed to be very simple to write. The examples/ folder
contains examples of Rust code compiled as WACC VM scripts as well as web
assembly text (wast) versions of scripts. Just like Bitcoin script, WACC VM
scripts are designed to be executed in pairs with an "unlock" script executing
before the "lock" script. The "unlock" script places key values on the virtual
stack, setting up the data necessary for the "lock" script to execute the
cryptographic operations. The goal is to be able to verify updates to the
key-value store state.
The primary use for WACC VM scripts is to provide control over who can append events to a provenance log. The scripting is necessary because provenance logs enforce a proof "precedence" whereby verification proofs of one kind take precendence over proofs of other kinds. This creates the capabilities necessary to build useful decentralized identity, intellectual property management, and general data provenance solutions on top.