The Polaris Prover License

StarkWare & Aztec Join Forces to Bring Forward an Innovative License for ZKP Provers

TL;DR:

• StarkWare is announcing the Polaris License, which relies on the immutability of permissionless blockchains.
• This is the license we intend to use for Prover source code made available to the ecosystem.
• Anyone may use and modify the Prover, as long as proofs are sent to a whitelisted Verifier on-chain; the whitelist of Verifiers is an append-only list.
• We collaborated with Aztec, developers of PLONK, and our talented competitors, in defining and adopting this license.

Introduction

This post describes the new Polaris license under which StarkWare plans to release source code for its STARK prover; Aztec will use the same Polaris license for its PLONK provers (see their post).
The Polaris license is applicable to computation services that combine an on-chain smart contract that interacts with off-chain code. Natural examples of such on-chain/off-chain interactions are proof systems used for scaling. Proof systems use a computationally-lean on-chain Verifier Smart Contract that receives proofs submitted by computationally-heavy off-chain Provers.
In particular, StarkNet Provers will be released under the Polaris license.

What does it say?

Informally, the Polaris license says that anyone may use and modify the Prover code, including for commercial use, as long as proofs generated by it are submitted to one of the white-listed Polaris Verifiers. A white-listed Verifier is a smart contract address appearing on an append-only list, which means that StarkWare may only add Verifiers to that list, but never remove them.

The name Polaris (North Star) captures the essence of the license. The Polaris is a faithful address to which compasses and maps can be pointed, assisting free-roaming travellers on their myriad forays. Like the star, a Polaris Verifier is everlasting¹ and unchanging.

Polaris as an Innovative Blockchain License

Blockchains are decentralized ledgers that manage ownership of digital assets, first and foremost — cryptocurrencies. With the advent of smart contracts and non-fungible tokens, blockchains are now also used to manage ownership of other digital assets, like digital art and collectibles, which are forms of intellectual property. The Polaris license takes a step further, managing off-chain intellectual property — software, while granting the flexibility needed to upgrade and maintain a live code-base.

For developers relying on the Prover code, this license eliminates the platform risk presented by technology providers such as StarkWare and Aztec. Platform risk is a major concern for developers, whether those platforms are quasi-monopolies or technology upstarts: Dominant platforms such as Facebook, Google, Facebook and Twitter pose a platform risk to developers, as they may unilaterally modify the terms of use of their platform, or shut it down altogether. Tech upstarts pose another risk: they may not survive in the long term, and so building on top of their software stack presents its own set of dangers. Polaris Verifiers are not merely guaranteed to exist indefinitely — their terms of use, whether gas-like or not, will also be made immutable by the blockchain, and thus provide developers with a stable business foundation to build upon.

For platform developers (StarkWare or Aztec, in this case), the Polaris framework ensures the sustainability of their business, which would allow funding research, engineering and product development. In particular, a Polaris Verifier may collect fees (gas-like or other) and distribute them among platform developers as well as application developers, proving service providers and other participants in the ecosystem.

What Motivated Us to Create this License?

Much of the code-base of public blockchains is open source. Tokenization has been the dominant means of monetizing these engineering efforts to date. While tokenization has its advantages, other approaches can and should be explored.

We believe the Polaris license will allow us to remain well-motivated in developing the STARK toolchain, including Cairo and StarkNet, and creating decentralized networks based on these tools. We support the need to provide full decentralization capabilities to our users, including the ability to self-custody assets and be protected against the platform risk associated with using our technology. These aspects are well-covered by the Polaris license.

Furthermore, we believe Polaris may serve as a central element in building StarkNet, and in building new applications in the blockchain ecosystem, in areas such as finance and gaming.

How did we Craft this License?

StarkWare and Aztec are competitors in the space of blockchain-related ZKP infrastructure. We have mutual respect and believe that both parties, and other players, may benefit from adopting a simple and sustainable business model that is facilitated by the Polaris license. Indeed, it is our hope that others will use this license.

And when it comes to the actual drafting, we relied on experts in the subject matter. In particular, the Polaris license was drafted by the best in the business, Heather Meeker, who led the licensing of Confluent, Redis, MongoDB SSPL, and the new PolyForm licenses.

Conclusion

The Polaris license is a new middle ground between open-source and source-available licenses. It is intended for a permissionless and decentralized world, and powered by it.

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¹Scientists predict Polaris will die in about 5,000,000 years. In blockchain time, that’s eternity.