What is an Execution Trace?

When a piece of code runs on a machine, the execution trace is a complete record of the computation: a snapshot of the full state of the machine at each clock cycle of the computation.

It's typical to write an execution trace as a rectangular array, where each row shows the complete state of the machine at a given moment in time, and each column shows a temporal record of some particular aspect of the computation (say, the value stored in a particular RISC-V register) at each clock cycle. A line-by-line analysis of the trace allows for a computational audit with respect to the program instructions and the underlying computer architecture.

RISC Zero's computational receipts use cutting-edge technology to audit an execution trace while preserving computational privacy.

The core of a RISC Zero receipt is a zk-STARK; for a more technical description of how we turn an execution trace into a zk-STARK, see the proof system sequence diagram and our STARK by Hand explainer.