# Version 0.1.0

### Deployment information <a href="#pdf-page-mdggx5w5crz8wwpzid8v-deployment-information" id="pdf-page-mdggx5w5crz8wwpzid8v-deployment-information"></a>

Source code: <https://github.com/Cardinal-Cryptography/zkOS-monorepo/releases/tag/v0.1.0>

Testnet Contracts:

* Shielder: [0x0019849f3fBA1ECd3fB4A2e27759e9432b19F6F3](https://evm-explorer-testnet.alephzero.org/address/0x0019849f3fBA1ECd3fB4A2e27759e9432b19F6F3)

Mainnet Contracts:

* Shielder: [0x48237d5B3659182b1B70Ccf8E4D077e812AaA5FF](https://evm-explorer.alephzero.org/address/0x48237d5B3659182b1B70Ccf8E4D077e812AaA5FF)

### Basic Information <a href="#pdf-page-mdggx5w5crz8wwpzid8v-basic-information" id="pdf-page-mdggx5w5crz8wwpzid8v-basic-information"></a>

This is the first release, considered beta, and thus it has several limitations aimed to provide protection for users while the code awaits a full audit and a few features are still under active development. The following list characterizes Version 0.1.0, with most of the restrictions expected to be lifted in the next release:

1. Only `AZERO` is supported for shielding. Stable coins and ERC20 tokens are not yet supported.
2. There is a limit of maximum `100 AZERO` to be deposited at once. Also, the user interface (Common App browser Extension) does not allow a user to hold more than `100 AZERO`in the shielded account, at any time.
3. Instead of the mechanism with Anonymity Revokers ([Anonymity Revokers](https://docs.common.fi/knowledge-base/protocol-details/anonymity-revokers)), another scheme with limited privacy is used in this release (see [PoW Anonymity Revoking](https://docs.common.fi/knowledge-base/protocol-details/pow-anonymity-revoking)). This will be replaced by the proper mechanism in the subsequent version.
4. The access to Shielder is fully permissionless and there are no Registrars (see [ZK-ID and Registrars](https://docs.common.fi/knowledge-base/protocol-details/zk-id-and-registrars)), this means anybody can create an account and there are no additional requirements.

### Technical Information on Circuits <a href="#pdf-page-mdggx5w5crz8wwpzid8v-technical-information-on-circuits" id="pdf-page-mdggx5w5crz8wwpzid8v-technical-information-on-circuits"></a>

While awaiting a full audit, the source code of the Halo2 circuits that we use stays in a private Github repository. The code of circuits will be published after the audit is finished and all findings have been addressed.

#### Notes and Hashing <a href="#pdf-page-mdggx5w5crz8wwpzid8v-notes-and-hashing" id="pdf-page-mdggx5w5crz8wwpzid8v-notes-and-hashing"></a>

For this release the structure of the note is as follows:

```rust
struct Note {
    version: Scalar, // version of the note structure. We start at 0
    id: Scalar, // the ZK-ID of a user
    trapdoor: Scalar, // a secret needed to prove ownership of the note
    nullifier: Scalar, // a secret used to invalidate the note
    balance_hash: Scalar, // the hash of the user's balance
} 
```

Specifically:

```rust
balance_hash = hash(balance, 0, 0, 0, 0, 0, 0)
```

Where `balance`is the user's `AZERO`balance — it is followed by `6`zeros before hashing (using Poseidon2 Hash). The reason for including the zeros, is to make it possible for a quite simple migration to a version that supports a limited number of ERC20 tokens (they would populate the 6 zeros). Since the maximum constant-arity Poseidon2 Hash that we support in out circuits is `7`the `6`zeros is the most natural choice.

The `Note`is then hashed simply as:

```rust
hash(version, id, trapdoor, nullifier, balance_hash)
```

using a `5-ary`Poseidon2 Hash.

#### Circuits and Constraints <a href="#pdf-page-mdggx5w5crz8wwpzid8v-circuits-and-constraints" id="pdf-page-mdggx5w5crz8wwpzid8v-circuits-and-constraints"></a>

Apart from some changes in hashing (explained above) the circuits in Version 0.1.0 mostly follow the PoC Version — see [PoC](https://open.gitbook.com/~space/jxGnEsASyxizmuYQHzry/~gitbook/pdf?back=false\&only=yes\&page=DPBKBtb8apDDzADGwat9#pdf-page-Hry3fqlDKhQWfukB7Hwt). The only significant difference is related to the introduction of:

* **Versioning.** Starting with this initial release each note has a version. We refer to [#versioning](https://docs.common.fi/knowledge-base/protocol-details/versioning) for a detailed discussion on that.
* **PoW Revoking.** We refer to [PoW Anonymity Revoking](https://docs.common.fi/knowledge-base/protocol-details/pow-anonymity-revoking).