# What trust assumptions exist in proposer-builder separation (PBS)?

**URL:** https://collective.flashbots.net/t/what-trust-assumptions-exist-in-proposer-builder-separation-pbs/151
**Category:** Searchers
**Tags:** question
**Created:** [August 24, 2022, 3:39am UTC](https://collective.flashbots.net/t/what-trust-assumptions-exist-in-proposer-builder-separation-pbs/151 "2022-08-24T03:39:56Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![brock](https://collective.flashbots.net/user_avatar/collective.flashbots.net/brock/32/5_2.png) [@brock](https://collective.flashbots.net/u/brock)
#### Post date: [August 24, 2022, 3:39am UTC](https://collective.flashbots.net/t/what-trust-assumptions-exist-in-proposer-builder-separation-pbs/151/1 "2022-08-24T03:39:56Z")

</div>

In this initial implementation of PBS (mev-boost), to prevent things like front-running, censorship, and unauthorized data sharing, each party has to trust the parties to which they connect. When PBS is [built natively](https://ethresear.ch/t/two-slot-proposer-builder-separation/10980) into the Ethereum protocol, these trust assumptions will be reduced by eliminating the need for relays.

- Searchers have to trust the builder(s) to which they send bundles.

- Builders have to trust the relay to which they send blocks.

- Validators have to trust the relay(s) from which they receive blocks.

Read more about the trust assumptions of mev-boost-enabled PBS in [Stephane’s research post](https://ethresear.ch/t/mev-boost-merge-ready-flashbots-architecture/11177).