pub enum Command {
Msg = 3,
Cbor = 16,
Init = 6,
Ping = 1,
Cancel = 17,
Err = 63,
KeepAlive = 59,
Wink = 8,
Lock = 4,
}Expand description
The CTAPHID protocol implements the following commands.
Variants§
Msg = 3
This command sends an encapsulated CTAP1/U2F message to the device. The semantics of the data message is defined in the U2F Raw Message Format encoding specification. See [passkey-rs::u2f].
Cbor = 16
This command sends an encapsulated CTAP CBOR encoded message. The semantics of the data message is defined in the CTAP Message encoding specification. Please note that keep-alive messages MAY be sent from the device to the client before the response message is returned.
Init = 6
This command has two functions.
If sent on an allocated CID, it synchronizes a channel, discarding the current transaction, buffers and state as quickly as possible. It will then be ready for a new transaction. The device then responds with the CID of the channel it received the INIT on, using that channel.
If sent on the broadcast CID, it requests the device to allocate a unique 32-bit channel identifier (CID) that can be used by the requesting application during its lifetime. The requesting application generates a nonce that is used to match the response. When the response is received, the application compares the sent nonce with the received one. After a positive match, the application stores the received channel id and uses that for subsequent transactions.
To allocate a new channel, the requesting application SHALL use the broadcast channel CTAPHID_BROADCAST_CID (0xFFFFFFFF). The device then responds with the newly allocated channel in the response, using the broadcast channel.
Ping = 1
Sends a transaction to the device, which immediately echoes the same data back. This command is defined to be a uniform function for debugging, latency and performance measurements.
Cancel = 17
Cancel any outstanding requests on this CID. If there is an outstanding request that can be cancelled, the authenticator MUST cancel it and that cancelled request will reply with the error CTAP2_ERR_KEEPALIVE_CANCEL.
As the CTAPHID_CANCEL command is sent during an ongoing transaction, transaction semantics do not apply. Whether a request was cancelled or not, the authenticator MUST NOT reply to the CTAPHID_CANCEL message itself. The CTAPHID_CANCEL command MAY be sent by the client during ongoing processing of a CTAPHID_CBOR request. The CTAP2_ERR_KEEPALIVE_CANCEL response MUST be the response to that request, not an error response in the HID transport.
A CTAPHID_CANCEL received while no CTAPHID_CBOR request is being processed, or on a non-active CID SHALL be ignored by the authenticator.
Err = 63
This command code is used in response messages only.
KeepAlive = 59
This command code is sent while processing a CTAPHID_MSG. It should be sent at least every 100ms and whenever the status changes. A KEEPALIVE sent by an authenticator does not constitute a response and does therefore not end an ongoing transaction.
Wink = 8
The wink command performs a vendor-defined action that provides some visual or audible identification a particular authenticator. A typical implementation will do a short burst of flashes with a LED or something similar. This is useful when more than one device is attached to a computer and there is confusion which device is paired with which connection.
Lock = 4
The lock command places an exclusive lock for one channel to communicate with the device. As long as the lock is active, any other channel trying to send a message will fail. In order to prevent a stalling or crashing application to lock the device indefinitely, a lock time up to 10 seconds may be set. An application requiring a longer lock has to send repeating lock commands to maintain the lock.