/*
 * Copyright 2023 Google LLC.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

syntax = "proto3";

package private_join_and_compute.anonymous_counting_tokens;

import "act/act.proto";
import "google/protobuf/timestamp.proto";


option java_multiple_files = true;

message Transcript {
  SchemeParameters scheme_parameters = 1;
  ServerParameters server_parameters = 2;
  ClientParameters client_parameters = 3;
  repeated string messages = 4;
  repeated bytes fingerprints = 5;
  TokensRequest tokens_request = 6;
  TokensRequestPrivateState tokens_request_private_state = 7;
  TokensResponse tokens_response = 8;
  repeated Token tokens = 9;
}

message MessagesSet {
  repeated string message = 1;
}

message GeneratedTokensRequestProto {
  repeated bytes fingerprints_bytes = 1;
  TokensRequest token_request = 2;
  TokensRequestPrivateState tokens_request_private_state = 3;
}

message TokensSet {
  repeated Token tokens = 1;
}

message Timestamp {
  // Represents seconds of UTC time since Unix epoch
  // 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
  // 9999-12-31T23:59:59Z inclusive.
  int64 seconds = 1;

  // Non-negative fractions of a second at nanosecond resolution. Negative
  // second values with fractions must still have non-negative nanos values
  // that count forward in time. Must be from 0 to 999,999,999
  // inclusive.
  int32 nanos = 2;
}


// Server public params request.
message GetServerPublicParamsRequest {
  // The response should contain the latest server params corresponding to this
  // scheme_params_version.
  string scheme_params_version = 1;
}

// Server public params response.
message GetServerPublicParamsResponse {
  // The name of the return parameters, to be used in subsequent token requests.
  string server_params_version = 1;
  ServerPublicParameters server_public_params = 2;
  // The time when tokens can be requested for these parameters.
  // After this expires, clients registered with these server params must
  // re-register with a new unexpired server_params.
  Timestamp server_params_sign_expiry = 3;
  // The time when tokens can be redeemed for these parameters.
  Timestamp server_params_join_expiry = 4;
}

message RequestMetadata {
  // AuthType decouples the authentication method from the platform or client.
  enum AuthType {
    AUTH_TYPE_UNSPECIFIED = 0;
    AUTH_GAIA = 1;
    AUTH_DEVICE_ATTESTATION = 2;
  }
  AuthType auth_type = 1;
  // Currently, only Android clients need to send metadata for authentication.
  oneof client {
    AndroidRequestMetadata android_request_metadata = 2;
  }
}

enum AttestationScheme {
  SCHEME_UNSPECIFIED = 0;
  SCHEME_X509_CERTIFICATE_CHAIN = 1;
}

// Authentication for Android devices, an alternative to Gaia.
message AndroidRequestMetadata {
  // Id of the client owning the device with the given attestation.
  bytes client_id = 1;
  // Android device attestation.
  bytes attestation = 2;
  AttestationScheme attestation_scheme = 3;
}

// Client registration request.
message RegisterClientRequest {
  reserved 3, 4;
  ClientPublicParameters client_public_params = 1;
  string server_params_version = 2;
  RequestMetadata request_metadata = 5;
}

// Client registration response.
message RegisterClientResponse {
  // The name given to the client parameters, to be used for all subsequent
  // token requests.
  string client_params_version = 1;
  // The time when tokens can be issued and redeemed for these parameters.
  Timestamp client_params_expiry = 2;
  // The time after which the client needs to reregister params.
  Timestamp client_reregister_expiry = 3;
}

message GetKeyAttestationChallengeResponse {
  // Transparently passed KA Challenge from KAVS
  bytes attestation_challenge = 1;
  // Timestamp of challenge expiration; given and managed by KAVS.
  Timestamp expiry = 2;
}

// Request to get tokens.
message GetTokensRequest {
  reserved 2, 5, 6;

  string client_params_version = 1;
  TokensRequest tokens_request = 3;

  // Client fingerprints are cryptographic objects that allow the server to
  // check whether the messages underlying tokens_request are different from
  // all previous requests from this client with these parameters.
  repeated bytes client_fingerprints_bytes = 4;

  RequestMetadata request_metadata = 7;
}

// Response containing tokens.
message GetTokensResponse {
  TokensResponse tokens_response = 1;
  // The time when tokens extracted from this response can be redeemed.
  Timestamp tokens_expiry = 3;
}

// Redeem token request.
message RedeemTokenRequest {
  reserved 3;
  // The token to be redeemed.
  Token token = 1;
  // The server params version associated with this token.
  string server_params_version = 2;
  // The message signed by this token.
  bytes token_message_bytes = 4;
}

// Redeem token response.
message RedeemTokenResponse {}

message JoinSetRequest {
  // The name of the set to join in types/{type}/sets/{set} format.
  // The type will have a maximum of 8 characters.
  // The set identifier will have a maximum of 64 characters.
  string name = 1;

  // The shortened (j-bit) client identifier.
  uint32 short_client_identifier = 4;

  reserved 2, 3;
}