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

description: |-
  Cancels a key verification process/request. Typically sent as a [to-device](/client-server-api/#send-to-device-messaging) event.
properties:
  content:
    properties:
      transaction_id:
        type: string
        description: |-
          The opaque identifier for the verification process/request.
      reason:
        type: string
        description: |-
          A human readable description of the `code`. The client should only rely on this
          string if it does not understand the `code`.
      code:
        type: string
        # Note: this is not an enum because we go into detail about the different
        # error codes. If we made this an enum, we'd be repeating information.
        # Also, we can't put a real bulleted list in here because the HTML2RST parser
        # cuts the text at weird points, breaking the list completely.
        description: |-
          The error code for why the process/request was cancelled by the user. Error
          codes should use the Java package naming convention if not in the following
          list:

          * `m.user`: The user cancelled the verification.

          * `m.timeout`: The verification process timed out. Verification processes
          can define their own timeout parameters.

          * `m.unknown_transaction`: The device does not know about the given transaction
          ID.

          * `m.unknown_method`: The device does not know how to handle the requested
          method. This should be sent for `m.key.verification.start` messages and
          messages defined by individual verification processes.

          * `m.unexpected_message`: The device received an unexpected message. Typically
          raised when one of the parties is handling the verification out of order.

          * `m.key_mismatch`: The key was not verified.

          * `m.user_mismatch`: The expected user did not match the user verified.

          * `m.invalid_message`: The message received was invalid.

          * `m.accepted`: A `m.key.verification.request` was accepted by a different
            device. The device receiving this error can ignore the verification request.

          Clients should be careful to avoid error loops. For example, if a device sends
          an incorrect message and the client returns `m.invalid_message` to which it
          gets an unexpected response with `m.unexpected_message`, the client should not
          respond again with `m.unexpected_message` to avoid the other device potentially
          sending another error response.
    required:
      - transaction_id
      - code
      - reason
    type: object
  type:
    enum:
      - m.key.verification.cancel
    type: string
type: object