# Proof of Productivity

## Overview

The Proof of Productivity is periodically executed, and its result (negative or positive) leads to and influences the reward distribution based on a multi-sig token re-issuance process on liquid.

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Under the assumption that a single point of notarized data (CID) exposes and thus discloses no relevant information, PoP can be viewed and interpreted as a multi-round zero-knowledge proof. 
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## Stages of Pop

The following stages of PoP exist:

1. [**Actor Selection**](https://docs.rddl.io/rddl-network/basics/proof-of-productivity/actor-selection)**:** The block-creating validator selects the PoP actors and initiates the PoP with the selected actors
2. [**Challenge-Response**](https://docs.rddl.io/rddl-network/basics/proof-of-productivity/challenge-response): The challenger and challengee execute/perform the PoP.
3. [**Rewards**](https://docs.rddl.io/rddl-network/basics/proof-of-productivity/rewards): The validators evaluate the notarized PoP Result and issue RDDL tokens as rewards.

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The current implementation is based on MQTT. The goal is to switch XMPP to guarantee a privacy-preserving PoP.
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