[meta] Element Web's requirements for `crypto-js`

[Hywan]

This is not a secret that Element Web will use matrix-sdk-crypto-js in a near future. This meta issue provides a list of additional features we want to see in matrix-sdk-crypto-js that are required for Element Web. This list is inspired by Element Web R: Internal Plan, and by various wishes I've heard here and there.

Each new feature respects the Rust team' standards: It is highly tested, well-documented, reviewed, and will improve the underlying layers if needed.

Foundational

• [x] Build pipeline for producing a NPM-compatible Wasm package:
  • [x] #966
  • [x] #981

Basic encryption/decryption

• [x] Storage implementation
  • [x] #971
• [x] Bindings for the minimal interface to support basic encryption/decryption
  • [x] #955
  • [x] #958
  • [x] #1040
• [ ] Fix bugs from community testing session

Table-stakes Functionality

• [x] Cross-signing bindings (Key Verification with Emojis, QR code, or manually, identity and bootstrapping)
  • [x] #788
• [x] Cross-signing shields/verification status
  • [x] OlmMachine.cross_signing_status is implemented, not sure if it validates this item
  • [x] #1039
• [x] Key backup bindings
  • [x] #1058
  • [x] #1059
• [x] Room key forwarding/key sharing
  • [x] #675
  • [x] #723
• [ ] Historical room key sharing
  • Not implemented in matrix_sdk_crypto yet.
• [ ] Custom to-device message bindings (for MSC3401 VoIP)
• [ ] Bindings to reset/replace key backup & cross-signing (and/or SSSS)
  • Not implemented in matrix_sdk_crypto yet.
• [ ] Fix bugs from community testing session

Ship It

• [ ] Test and address performance concerns if any
• [ ] Fix bugs from community testing session