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title: Summa - Memo for CEX
tags: [business]

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# Summa - Memo for CEX

### What

[Summa](https://github.com/summa-dev) is an open-source software for any CEX that wants to provide **auditor-less** and **private** proof of solvency to their users.

Zero-knowledge cryptography is being employed to: 

- Replace auditor-based guarantee of integrity with cryptographic-based guarantee of integrity
- Not reveal sensitive data of the CEX (and its users) to the public, such as:
    - Individual user information such as their balances and usernames (V1)
    - The total number of users (V1)
    - The total amount of liabilities (V1)
    - The total amount of assets controlled by the CEX (V2)
    - The addresses of the wallets controlled by the CEX (V2)

### Who

Summa is a team part of the Ethereum Foundation, Privacy and Scaling Exploration Branch. Its members are: 

- [Enrico Bottazzi](https://github.com/enricobottazzi), team lead and engineer, previously Iden3 and Polygon Hermez
- [Jin](https://github.com/sifnoc), researcher & engineer
- [Alex Kuzmin](https://github.com/alxkzmn), engineer


### How to use it

The CEX needs to provide two csv files:
- a file containing the liabilities data (`username -> balance`)
- a file containing the asset data (list of the verified address controlled).

The locally run API will assemble the liabilities data into a Merkle Sum Tree and generate proofs for each user of the exchange that may require it. 

![](https://hackmd.io/_uploads/rkP5Wy9S3.png)

By verifying a proof, each user is confident that they have been correctly accounted for within CEX’s liabilities and that the sum of the liabilities is less than the total assets.

### Know More

The latest updates on Summa have been presented at EthCC Paris by Enrico. [Here](https://www.youtube.com/watch?v=cG-Y4-6kp68) you can find the recording of the presentation


### Contact Us

We invite you to participate in the testing phase of Summa. We'll show you how this can be used and gather feedback from you. The goal is to set the standard for transparency and trust in the cryptocurrency exchange sector.

**This memo does not constitute an invite for formal partnership or collaboration**

Alex
- telegram: @snarkrider
- email: alex.kuzmin@proton.me

Enrico
- telegram: @demivoleegaston
- email: enricobottazzi@icloud.com

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