# Guarantor

## Overview

A guarantor is the account that provides guarantee for one or multiple validators in Crust Network. Any account with CRU tokens can potentially become a guarantor while in turn obtaining guarantee incomes. Additionally, the guarantor can maintain the security of the network by choosing validators with quality performance.

## Guarantors’ Rewards and Slash

Currently, Crust Network is at the prview stage - Maxwell. Therefore, the following reward and punishment specifications only concern rules and parameters pertaining to Maxwell.

### 1. Rewards

The guarantor obtains rewards from staking, which is influenced by the following factors:

- Stake Limit: The Stake Limit determines the upper limit of the effective stake of CRUs by the validator, which is directly related to the amount of storage provided by the validator. In Maxwell, a 1TB SRD file corresponds to an upper limit of 1CRU, and a meaningful file corresponds to 1-5 times the upper limit of SRD, with specific ‘times’ related to the number of duplicates of meaningful files. For details, please refer to DSM Guidance;
- Effective Stake: The Effective Stake is
**the amount of staking that actually generates incomes**, which is related to the stake limit of the validator that is guaranteed. An example is provided as follows:

For example, if the validator obtains 900 CRU staking rewards and 100 CRU authoring reward (block generation reward) in one era, and if his self-staking accounts for 90% of his total staking(The remaining 10% is contributed by guarantors). If the guarantee fee is 95%, then the guarantors finally obtains (900 + 100) * 10% * 95% = 95 CRUs income, and the remaining 905 CRUs belongs to the validator. If a validator’s stake limit is 1000 CRU, the self-staking is 900 CRU, and the guarantor staked 300 CRU. In this way, the total stake is 1200, and the total effective pledge is 1000. The effactive stake of the validator is 1000 * (900/1200) = 750, and the effective stake of the guarantor is 1000 * (300/1200) = 250.

How are the rewards specifically distributed? **First, in Maxwell, each Era (6 hours) will generate a staking reward of 600 CRUs, which gets halved every 90 days.** The income obtained by the guarantor is calculated as following:

```
guarantor_rewards = total_staking_income * guarantor_effective_staking_amount / total_effective_staking_amount * guarantee_fee
```

```
validator_total_staking_amount = validator_self_staking_amount + guarantee_amount
```

```
guarantor_effective_guarantee_amount = MIN (stake_limit, validator_total_staking_amount) * (guarantee_amount / validator_total_staking_amount)
```

Here is an example:

If node A staked 1000 CRUs itself, for which you guaranteed 200 CRUs. The stake limit is 1000 CRUs, with the percentage of guarantee fee set at 95%, and the staking incomes generated per round are 600 CRUs. Supposing the effective staking amount of the network is 2000, we can work out the income of each Era:

- Effective staking amount = minimum value (1000, 1200) * (200 / 1200) = 1000 * (200 / 1200) = 166.66 CRU
- Staking income = 600 * (166.66 / 2000) * 95% = 47.498 CRU

### 2. Slash

The guarantor and the validator guaranteed by him have the same slash ratio. For details of the slash, please refer to slash specifications in Validator.

## How to Guarantee

Please refer to Guarantee Guidance for details.