---
description: >-
  Signature aggregators in Ethereum compile multiple approvals. Bundlers oversee
  their trustworthiness by assessing their Ethereum stake and validity, ensuring
  smooth, secure operations.
---

# Using Signature Aggregators

## **Utilizing Signature Aggregators in Ethereum**

In some cases, Ethereum accounts might want to use something called "signature aggregators". Here's how they work:

**Indicating Usage of Signature Aggregators**:

If an account wants to use a signature aggregator, it'll give a heads-up by returning its address when `validateUserOp` is called. If the bundler then uses `simulateValidation`, the aggregator's address is provided in the resulting `ValidationResultWithAggregator`.

**Bundler's Duties**:

Before a bundler proceeds, they need to ensure that the aggregator is trustworthy. This involves:

* Confirming that the aggregator has enough at stake (essentially ensuring that the aggregator has something to lose if they act maliciously).
* Making sure the aggregator isn't currently restricted or banned for some reason.
* Using the `aggregator.validateUserOpSignature()` method to confirm the `userOp` is legitimate.

**Requirements for Signature Aggregators**:

These aggregators should generally put some Ethereum (or "stake") on the line, much like a guarantor would. This acts as a security deposit to ensure good behavior. There are, however, some exceptions to this. For instance, if the aggregator doesn't access global storage, it might be exempt from staking.

Bundlers also have the authority to restrict or even ban aggregators if they're too resource-heavy, make errors, or if their signature gathering doesn't go as planned.

In essence, signature aggregators streamline certain Ethereum processes, but to ensure security, they are closely checked and monitored by bundlers.
