---
allOf:
  - $ref: core-event-schema/event.yaml

description: |-
  This event type is used to exchange keys for end-to-end encryption.
  It is encrypted as an `m.room.encrypted` event using [Olm](#molmv1curve25519-aes-sha2),
  then sent as a [to-device](/client-server-api/#send-to-device-messaging) event.
properties:
  content:
    properties:
      algorithm:
        type: string
        enum: ["m.megolm.v1.aes-sha2"]
        description: |-
          The encryption algorithm the key in this event is to be used with.
      room_id:
        type: string
        description: The room where the key is used.
      session_id:
        type: string
        description: The ID of the session that the key is for.
      session_key:
        type: string
        description: The key to be exchanged.
      shared_history:
        type: boolean
        description: |-
          Whether the key may be forwarded to users who join the room after the
          messages encrypted with this key have been sent.  Defaults to
          `false`.

          This can be set to `true` if the history visibility settings of the
          room allow users to read events in the room from before they have
          joined, that is, if the `m.room.history_visibility` state event is
          `"world_readable"` or `"shared"`. For more information, see [Key
          requests and forwarding](#key-requests-and-forwarding).
    required:
      - algorithm
      - room_id
      - session_id
      - session_key
    type: object
  type:
    enum:
      - m.room_key
    type: string
type: object