# Wallet Key Management - Tech Overview

Once a user creates an account using Metafi Login or your custom signup flow, a wallet (BIP39 seed phrase) is generated on the user device for each of the chains supported by your game. We then generate a 128-bit random ID (**encKey**) which is used to encrypt each wallet. We use the AES-256-CTR standard for all of our encryption.

This **encKey** is then split into 3 shares using [Shamir's Secret Sharing algorithm](https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing). We implement a 2/3 threshold scheme, where we need any 2 out of 3 shares to successfully recover the **encKey**. Two shares are then sent to the backend (**ms** and **cs**), and the third share is saved in the user's device (**us**).

The **ms** and **cs** shares are encrypted and secured via [AWS hardware security modules](https://aws.amazon.com/kms/). You have the option of storing one of the shares (**cs**) on your own backend, which can be done by setting URLs to store and fetch the **cs** share as outlined [here](https://docs.usemeta.fi/start/about/self-hosting-shares).

Once a user verifies their identity by logging in, we return the **ms** share to the user, which is combined with the **us** share on the users device to recover the **encKey**. This **encKey** is then used to decrypt the wallets, and the user can then continue with making transactions.

We are working on adding additional modes of recovery in the future such as security questions and downloading a recovery key. Please reach out to us via our [Discord](https://discord.gg/yaxvxEmuKn) if you have any questions.