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# Wallets

This page describes some basic approaches to Ethereum wallets and accounts.

All you really need is a private key. From that, you can derive the Ethereum address. An Ethereum "account" is a combination of private key and Eth address.

A "wallet" is a thing that stores private keys (and maybe signs transactions). This includes Metamask (browser plugin), Trezor (hardware wallet), and more. [Ocean docs on wallets](https://docs.oceanprotocol.com/tutorials/wallets/) has more information.

Here we describe:

1.  How to generate private keys
2.  Where to store private keys
3.  How your software might access accounts

## 1. How to generate private keys

### Generate in browser with Metamask

The datatokens tutorial described how to install Metamask, then use one the Ethereum accounts it auto-generates (along with the private key).

### Generate in Javascript

ocean-lib includes the [web3.js library](https://web3js.readthedocs.io/en/) which can generate private keys. 
Here's how. In Javascript:

```javascript
const Web3 = require('web3');
const web3Provider = new Web3js.providers.WebsocketProvider(`wss://mainnet.infura.io/ws/v3/INFURA_PROJECT_ID`);
const web3 = new Web3(web3Provider);
const account = await web3.eth.accounts.create();
const privateKey = account.privateKey;
```

## 2. Where to store private keys

The _whole point_ of crypto wallets is store private keys. Wallets have various tradeoffs of cost, convienence, and security. For example, hardware wallets tend to be more secure but less convenient and not free.

It can also be useful to store private keys locally on your machine, for testing, though only with a small amount of value at stake (keep the risk down 🐙).

Do _not_ store your private keys on anything public, unless you want your tokens to disappear. For example, don't store your private keys in GitHub or expose them on frontend webpage code.

## 3. How your software might access Ethereum accounts

There are two main ways: (a) directly load private key, and (b) as a keyfile JSON object. Let's review each.

### 3a. Directly load private key

You could grab this from a locally-stored file, or from an envvar that you copy in for a new session. Here we focus on the latter.

First, make your key available as an envvar. Here's an example key. From your console:

```console
export MY_TEST_KEY=0xaefd8bc8725c4b3d15fbe058d0f58f4d852e8caea2bf68e0f73acb1aeec19baa
```

The Ethereum address that gets computed from the example key is `0x281269C18376010B196a928c335E495bd05eC32F`.


### 3b. Keyfile JSON object, aka EncryptedKey

Here's an example JSON object. This example has the same private key as above, and password `OceanProtocol` to encrypt/decrypt the private key. The private key is stored as parameter `ciphertext` (in encrypted form, of course).

```json
    {
      "address": "281269c18376010b196a928c335e495bd05ec32f",
      "crypto": {
        "cipher": "aes-128-ctr",
        "cipherparams": {
          "iv": "ac0b74c5100bd319030d983029256250"
        },
        "ciphertext": "6e003d25869a8f84c3d055d4bda3fd0e83b89769b6513b58b2b76d0738f2ab1c",
        "kdf": "pbkdf2",
        "kdfparams": {
          "c": 1000000,
          "dklen": 32,
          "prf": "hmac-sha256",
          "salt": "423c1be88c1fadd926c1b668a5d93f74"
        },
        "mac": "6b90720ddc10d457c2e3e7e1b61550d7a7fa75e6051cb1ed4f1516fba4f0a45f"
      },
      "id": "7954ec59-6819-4e3c-b065-e6f3a9c1fe6c",
      "version": 3
    }
```

Here's how you use the JSON object. In your console, export the EncryptedKey and password:

```console
export MY_TEST_ENCRYPTED_KEY='{"address": "281269c18376010b196a928c335e495bd05ec32f", "crypto": {"cipher": "aes-128-ctr", "cipherparams": {"iv": "ac0b74c5100bd319030d983029256250"}, "ciphertext": "6e003d25869a8f84c3d055d4bda3fd0e83b89769b6513b58b2b76d0738f2ab1c", "kdf": "pbkdf2", "kdfparams": {"c": 1000000, "dklen": 32, "prf": "hmac-sha256", "salt": "423c1be88c1fadd926c1b668a5d93f74"}, "mac": "6b90720ddc10d457c2e3e7e1b61550d7a7fa75e6051cb1ed4f1516fba4f0a45f"}, "id": "7954ec59-6819-4e3c-b065-e6f3a9c1fe6c", "version": 3}'
export MY_TEST_PASSWORD=OceanProtocol
```