# How private and secure is Brave Sync?

**URL:** https://discuss.privacyguides.net/t/how-private-and-secure-is-brave-sync/225
**Category:** Questions
**Tags:** browsers
**Created:** 2022-10-04T05:42:05Z
**Posts:** 3
**Showing post:** 3 of 3

## Post 3 by @anon34719932 — 2022-10-04T09:26:28Z

> **Tl;dr** : @InconspicuousEntity is right: it uses a sync chain to transfer sensitive data, using zero-access E2EE. I think it’s a great option.

**Details**

Brave Sync [claims](https://github.com/brave/brave-browser/wiki/Brave-Sync-v2#differences-from-chromium-sync) that it

1. enforce[s] client side encryption;
2. doesn’t require sign-in to use sync; […]
3. [and] uses a Brave-operated sync server so no data is sent to Google servers.

To circumvent weak passphrases, it uses Chromium’s built-in [`custom passphrase`](https://github.com/brave/brave-browser/wiki/Brave-Sync-v2#client-side-encryption) feature to provide authenticated key-pair encryption.

- The first client generates a random, encoded seed.
- A new client enters the keyphrase (e.g. manual entry or QR code).
- The server authenticates the exchange.
- The keyphrase is stretched, and a salt is stored by the server.
- Future clients receive the salt and can derive the stretched keyphrase, which is used as the encryption key!

[GitHub Wiki](https://github.com/brave/brave-browser/wiki/Brave-Sync-v2#authentication) | [Source Code](https://github.com/brave/go-sync) | [FAQ](https://support.brave.com/hc/en-us/articles/360047642371) | [Help Article](https://support.brave.com/hc/en-us/articles/360059793111-Understanding-Brave-Sync)

Based on the sync design and my inspection (2022.10.04) of the source code (primarily the authentication of keyphrase exchange, scrypt stretch and salt transmission, and the client-side AES128-CTR-HMAC encryption), I think there’s good evidence for those claims. :smile:

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