Merge pull request #529 from oasisprotocol/amela/e-upgrade-23.0

docs/node/mainnet: Add major features draft for upcoming 23.0

docs/node/mainnet/e-upgrade.md

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+# E* Upgrade
+
+This document provides an overview of the changes for the E* Mainnet
+upgrade.
+
+:::caution
+
+The E* upgrade on Mainnet is scheduled at epoch TODO which will happen
+around TODO.
+
+:::
+
+## Major Features
+
+All features for the E* upgrade are implemented as part of
+**Oasis Core 23.0.x** release series which is a consensus protocol-breaking
+release.
+
+Summary of the major features is as follows:
+
+- **On-Chain Governance**:
+  - The upgrade adds support for delegators to participate in on-chain
+    governance. So far, only validators have been able to vote on governance
+    proposals on upgrades. From now on, anyone who is staking will be able to
+    override the votes of the validator.
+  - Prior to this upgrade, validators could vote solely on one specific type of
+    upgrade proposal. This upgrade adds support for voting on parameter changes.
+    An example of such a change includes voting on the staking rewards schedule
+    modifications.
+
+- **Node Operators UX**:
+  - With the enhancement of the P2P Stack in the latest upgrade, we've
+    integrated support for state sync. This improvement simplifies the process
+    of initiating a new node, enabling immediate synchronization without the
+    need for manual RPC node configuration.
+  - The upgrade lays the foundation for the system to distribute bundles
+    automatically. While this update doesn't enable this feature, in the future
+    nodes will have the capability to upgrade automatically to the appropriate
+    version immediately after a governance vote passes.
+  - Enhancements have been made to bolster security and optimize the efficiency
+    of specific queries.
+
+- **Key rotations**:
+  - The upgrade introduces major updates to facilitate key rotations. Support
+    will be provided for both ephemeral and session keys.
+    - The ephemeral key will rotate every epoch, and its entropy will be
+      discarded after a few epochs. As a result, past transaction keys will be
+      irretrievable unless the user enables disclosure of past transactions.
+    - The upgrade introduces support for state key rotations, incorporating key
+      generations. Users can now rotate state keys daily, and with each new
+      state, generate new keys. This facilitates re-encryption and, in the event
+      of a TCB recovery, helps to partially mitigate the effects of compromised
+      nodes.
+
+- **ParaTime Upgrades**:
+  - The current Sapphire paratimes have a block delay following transaction
+    execution. The Upcoming version introduces same-block execution. As soon as
+    a block gets finalized on the consensus layer, developers can promptly
+    obtain the latest root hash of the runtime and verify the state without
+    delay. This reduces latency for those looking to verify the outcomes of
+    their transactions, making the process more efficient, especially for dApp
+    developers.
+  - The upgrade reduces the downtime associated with upgrading TEE-based
+    runtimes. Previously, an upgrade to Sapphire mandated an epoch of downtime.
+    Now, as compute nodes transition to the new version, the upgrade will be
+    instantaneous, ensuring no delays or downtime.
+
+- **ParaTime Performance**:
+  - The upgrade implements a series of modifications to enhance the robustness
+    of runtimes. These improvements encompass better response mechanisms for SGX
+    TCB recovery events, expanded support for new SGX platforms, and improved
+    proof validation within runtimes.
+  - The upgrade improves runtime performance, especially in scenarios involving
+    node failures. Should nodes malfunction, the impact on performance will now
+    be significantly reduced.
+
+
+## Mechanics of the Upgrade
+
+:::info
+
+This section will be updated with the exact details as we get closer to the
+upgrade.
+
+:::