# Epoch Key And Proof

* An epoch key is the only way that a user can receive reputation.
* A user can generate an epoch key with a nonce, the nonce should be less than `numEpochKeyNoncePerEpoch`.
* A user generates the epoch key with a Circom circuit and the epoch key and proof can be verified by attesters in Unirep smart contract.

### `genEpochKeyAndProof`

```
npx ts-node cli/index.ts genEpochKeyAndProof 
                  [-h] 
                  [-e ETH_PROVIDER] 
                  -id IDENTITY 
                  -n EPOCH_KEY_NONCE 
                  [-b START_BLOCK] 
                  -x CONTRACT
```

* epoch key and base64url encoded epoch key proof will be printed
* A string with `Unirep.epkProof` prefix is the proof of this epoch key

### Options

```
  -e ETH_PROVIDER, --eth-provider ETH_PROVIDER
                        A connection string to an Ethereum provider. Default: http://localhost:8545
  -id IDENTITY, --identity IDENTITY
                        The (serialized) user's identity
  -n EPOCH_KEY_NONCE, --epoch-key-nonce EPOCH_KEY_NONCE
                        The epoch key nonce
  -b START_BLOCK, --start-block START_BLOCK
                        The block the Unirep contract is deployed. Default: 0
  -x CONTRACT, --contract CONTRACT
                        The Unirep Social contract addres
```

#### Options inherited from parent commands <a href="#options-inherited-from-parent-commands" id="options-inherited-from-parent-commands"></a>

```
  -h, --help            Show this help message and exit.
```

### `verifyEpochKeyProof`

```
npx ts-node cli/index.ts verifyEpochKeyProof 
                  [-h] 
                  [-e ETH_PROVIDER] 
                  -epk EPOCH_KEY 
                  -pf PROOF 
                  [-b START_BLOCK] 
                  -x CONTRACT
```

* This command will help other users with an epoch key proof with `Unirep.epkProof` prefix to call the Unirep smart contract to verify the proof.
* The input should match the claim that the prover provides.

### Options

```
  -e ETH_PROVIDER, --eth-provider ETH_PROVIDER
                        A connection string to an Ethereum provider. Default: http://localhost:8545
  -epk EPOCH_KEY, --epoch-key EPOCH_KEY
                        The user's epoch key (in hex representation)
  -pf PROOF, --proof PROOF
                        The snark proof of the user's epoch key
  -b START_BLOCK, --start-block START_BLOCK
                        The block the Unirep contract is deployed. Default: 0
  -x CONTRACT, --contract CONTRACT
                        The Unirep Social contract address
```

#### Options inherited from parent commands <a href="#options-inherited-from-parent-commands" id="options-inherited-from-parent-commands"></a>

```
  -h, --help            Show this help message and exit.
```