Rollout progressively the new Rust crypto SDK

[odelcroi]

See : https://github.com/element-hq/element-web/blob/develop/docs/labs.md#use-the-rust-cryptography-implementation-feature_rust_crypto-in-development

This new crypto SDK is on by default but can be deployed progressively, what should we do?

[estellecomment]

From docs :

For administrators looking to transition existing users to the new stack, the RustCrypto.staged_rollout_percent configuration is available.
This configuration allows for a phased migration of users, represented as an integer percentage (0 to 100). By default, this value is set to 0,
which means no existing users will be migrated to the new stack. If you wish to migrate all users, you can adjust this value to 100.

This configuration should be placed under the setting_defaults section as shown:

    "setting_defaults": {
        "RustCrypto.staged_rollout_percent": 20
    },

[estellecomment]

From comments in https://github.com/matrix-org/matrix-react-sdk/blob/v3.92.0/src/MatrixClientPeg.ts#L331
"At some point, we'll allow the user to enable the setting via labs, which will migrate their existing
// device to the rust-sdk implementation"

[estellecomment]

Tests I made on tchap with 1.11.58 for behavior of flag :

• add flag to disable crypto in config and test behavior
  • set flag to false : no changes in crypto (according to Aide et A propos), still olm
  • set flag to true, reload page : no changes in crypto, still olm
  • logout, login : crypto is now rust. Messages in various channels take a few seconds to arrive, but not long enough for me to do something about it.
  • set flag to false, reload page : current device stays in rust crypto.
  • logout, login (flag is still false) : crypto is back to olm

Any existing devices keep their crypto type (rust or olm), even if the server flag changes.
When the flag is true (or absent : default = true), any new logins will create a rust-crypto device.
When the flag is false, any new logins will create a olm-crypto device.

(this is exactly what the docs say, happily :) )

[MarcWadai]

Don't start the rollout until this issue is fix on element side: element-hq/element-web#27165

This problem has flooded our server. CPU charge of main worker works at 120% due to Element Web users in instance "social" and "finance"

[odelcroi]

Matrix JS sdk 33 fixes the problem : matrix-org/matrix-js-sdk#4216

https://github.com/matrix-org/matrix-js-sdk/releases/tag/v33.0.0

[MarcWadai]

• Check the stats to see how many people have activated secure backup in web. To mitigate risk of messages loss during migration
• Check no more blocking issues are open about rust crypto