Summa is a Zero-Knowledge Proof of Reserves tool designed for custodial services that hold cryptocurrency, such as centralized exchanges. It was developed within PSE with support from the Ethereum Foundation.

Summa enables Custodians to cryptographically prove that the total Assets they hold in reserve exceed their Liabilities, while keeping sensitive user data private. It enables Customers to independently verify the solvency of the Custodian with less reliance on trusted third-party auditors.

$Assets\ge Liabilities$

Or, in simpler terms, the Custodian has the assets to cover all the balances of its users so that they can withdraw their funds at any time.

Read more about how Summa works and how to deploy it in the Docs.