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

description: |-
  Begins a key verification process. The `method` field determines the type of
  verification. The fields in the event will differ depending on the `method`.
  This definition includes fields that are in common among all variants.
properties:
  content:
    properties:
      from_device:
        type: string
        description: |-
          The device ID which is initiating the process.
      transaction_id:
        type: string
        description: |-
          Required when sent as a to-device message unless the start event is
          sent without a corresponding
          [`m.key.verification.request`](#mkeyverificationrequest).

          An opaque identifier for the verification process. Must be unique
          with respect to the devices involved.

          Must be the same as the `transaction_id` given in the
          [`m.key.verification.request`](#mkeyverificationrequest) if this
          process is originating from a request.

          Note that sending a start event without a request is deprecated, and
          clients should not send a start event without first sending a request
          event, but clients should handle other clients doing so.
      method:
        type: string
        description: |-
          The verification method to use.
      next_method:
        type: string
        description: |-
          Optional method to use to verify the other user's key with. Applicable
          when the `method` chosen only verifies one user's key. This field will
          never be present if the `method` verifies keys both ways.
      m.relates_to:
        description: |-
          Required when sent as an in-room message unless the start event is
          sent without a corresponding
          [`m.key.verification.request`](#mkeyverificationrequest).

          Indicates the
          [`m.key.verification.request`](#mkeyverificationrequest) that this
          message is related to. Note that for encrypted messages, this
          property should be in the unencrypted portion of the event.

          Note that sending a start event without a request is deprecated, and
          clients should not send a start event without first sending a request
          event, but clients should handle other clients doing so.
        properties:
          rel_type:
            type: string
            enum:
              - m.reference
            description: |-
              The relationship type. Currently, this can only be an
              [`m.reference`](/client-server-api/#reference-relations)
              relationship type.
          event_id:
            type: string
            description: |-
              The event ID of the
              [`m.key.verification.request`](#mkeyverificationrequest) that
              this message is related to.
        type: object
        title: VerificationRelatesTo
    required:
      - from_device
      - method
    type: object
  type:
    enum:
      - m.key.verification.start
    type: string
type: object