syntax = "proto2";
package hw.trezor.messages.thp;

// Sugar for easier handling in Java
option java_package = "com.satoshilabs.trezor.lib.protobuf";
option java_outer_classname = "TrezorMessageThp";


/**
 * Numeric identifiers of pairing methods.
 * @embed
 */
enum ThpPairingMethod {
    NoMethod = 1;             // Trust without MITM protection.
    CodeEntry = 2;            // User types code diplayed on Trezor into the host application.
    QrCode = 3;               // User scans code displayed on Trezor into host application.
    NFC_Unidirectional = 4;   // Trezor transmits an authentication key to the host device via NFC.
}

/**
 * @embed
 */
message ThpDeviceProperties {
    optional string internal_model = 1;               // Internal model name e.g. "T2B1".
    optional uint32 model_variant = 2;                // Encodes the device properties such as color.
    optional bool bootloader_mode = 3;                // Indicates whether the device is in bootloader or firmware mode.
    optional uint32 protocol_version = 4;             // The communication protocol version supported by the firmware.
    repeated ThpPairingMethod pairing_methods = 5;    // The pairing methods supported by the Trezor.
}

/**
 * @embed
 */
message ThpHandshakeCompletionReqNoisePayload {
    optional bytes host_pairing_credential = 1;       // Host's pairing credential
    repeated ThpPairingMethod pairing_methods = 2;    // The pairing methods chosen by the host
}

/**
 * Request: Ask device for a new session with given passphrase.
 * @start
 * @next ThpNewSession
 */
message ThpCreateNewSession{
    optional string passphrase = 1;
    optional bool on_device = 2;       // User wants to enter passphrase on the device
    optional bool derive_cardano = 3;  // If True, Cardano keys will be derived. Ignored with BTC-only
}

/**
 * Response: Contains session_id of the newly created session.
 * @end
 */
message ThpNewSession{
    optional uint32 new_session_id = 1;
}

/**
 * Request: Start pairing process.
 * @start
 * @next ThpCodeEntryCommitment
 * @next ThpPairingPreparationsFinished
 */
message ThpStartPairingRequest{
    optional string host_name = 1;      // Human-readable host name
}

/**
 * Response: Pairing is ready for user input / OOB communication.
 * @next ThpCodeEntryCpace
 * @next ThpQrCodeTag
 * @next ThpNfcUnidirectionalTag
 */
 message ThpPairingPreparationsFinished{
}

/**
 * Response: If Code Entry is an allowed pairing option, Trezor responds with a commitment.
 * @next ThpCodeEntryChallenge
 */
message ThpCodeEntryCommitment {
    optional bytes commitment = 1;     // SHA-256 of Trezor's random 32-byte secret
}

/**
 * Response: Host responds to Trezor's Code Entry commitment with a challenge.
 * @next ThpPairingPreparationsFinished
 */
message ThpCodeEntryChallenge {
    optional bytes challenge = 1;      // host's random 32-byte challenge
}

/**
 * Request: User selected Code Entry option in Host. Host starts CPACE protocol with Trezor.
 * @next ThpCodeEntryCpaceTrezor
 */
message ThpCodeEntryCpaceHost {
    optional bytes cpace_host_public_key = 1;    // Host's ephemeral CPace public key
}

/**
 * Response: Trezor continues with the CPACE protocol.
 * @next ThpCodeEntryTag
 */
message ThpCodeEntryCpaceTrezor {
    optional bytes cpace_trezor_public_key = 1;  // Trezor's ephemeral CPace public key
}

/**
 * Response: Host continues with the CPACE protocol.
 * @next ThpCodeEntrySecret
 */
message ThpCodeEntryTag {
    optional bytes tag = 2;       // SHA-256 of shared secret
}

/**
 * Response: Trezor finishes the CPACE protocol.
 * @next ThpCredentialRequest
 * @next ThpEndRequest
 */
message ThpCodeEntrySecret {
    optional bytes secret = 1;    // Trezor's secret
}

/**
 * Request: User selected QR Code pairing option. Host sends a QR Tag.
 * @next ThpQrCodeSecret
 */
message ThpQrCodeTag {
    optional bytes tag = 1;       // SHA-256 of shared secret
}

/**
 * Response: Trezor sends the QR secret.
 * @next ThpCredentialRequest
 * @next ThpEndRequest
 */
message ThpQrCodeSecret {
    optional bytes secret = 1;    // Trezor's secret
}

/**
 * Request: User selected Unidirectional NFC pairing option. Host sends an Unidirectional NFC Tag.
 * @next ThpNfcUnidirectionalSecret
 */
message ThpNfcUnidirectionalTag {
    optional bytes tag = 1;       // SHA-256 of shared secret
}

/**
 * Response: Trezor sends the Unidirectioal NFC secret.
 * @next ThpCredentialRequest
 * @next ThpEndRequest
 */
message ThpNfcUnidirectionalSecret {
    optional bytes secret = 1;    // Trezor's secret
}

/**
 * Request: Host requests issuance of a new pairing credential.
 * @start
 * @next ThpCredentialResponse
 */
message ThpCredentialRequest {
    optional bytes host_static_pubkey = 1;       // Host's static public key used in the handshake.
}

/**
 * Response: Trezor issues a new pairing credential.
 * @next ThpCredentialRequest
 * @next ThpEndRequest
 */
message ThpCredentialResponse {
    optional bytes trezor_static_pubkey = 1;     // Trezor's static public key used in the handshake.
    optional bytes credential = 2;               // The pairing credential issued by the Trezor to the host.
}

/**
 * Request: Host requests transition to the encrypted traffic phase.
 * @start
 * @next ThpEndResponse
 */
message ThpEndRequest {}

/**
 * Response: Trezor approves transition to the encrypted traffic phase
 * @end
 */
message ThpEndResponse {}

/**
 * Only for internal use.
 * @embed
 */
 message ThpCredentialMetadata {
    optional string host_name = 1;     // Human-readable host name
}

/**
 * Only for internal use.
 * @embed
 */
 message ThpPairingCredential {
    optional ThpCredentialMetadata cred_metadata = 1; // Credential metadata
    optional bytes mac = 2;                           // Message authentication code generated by the Trezor
}

/**
 * Only for internal use.
 * @embed
 */
 message ThpAuthenticatedCredentialData {
    optional bytes host_static_pubkey = 1;            // Host's static public key used in the handshake
    optional ThpCredentialMetadata cred_metadata = 2; // Credential metadata
}