syntax = "proto3";

//
// Copyright 2020 Signal Messenger, LLC.
// SPDX-License-Identifier: AGPL-3.0-only
//

package signal.proto.storage;

message SessionStructure {
  message Chain {
    bytes sender_ratchet_key         = 1;
    bytes sender_ratchet_key_private = 2;

    message ChainKey {
      uint32 index = 1;
      bytes  key   = 2;
    }

    ChainKey chain_key = 3;

    message MessageKey {
      uint32 index      = 1;
      bytes  cipher_key = 2;
      bytes  mac_key    = 3;
      bytes  iv         = 4;
    }

    repeated MessageKey message_keys = 4;
  }

  message PendingPreKey {
    uint32 pre_key_id        = 1;
    int32  signed_pre_key_id = 3;
    bytes  base_key          = 2;
  }

  uint32         session_version            = 1;
  bytes          local_identity_public      = 2;
  bytes          remote_identity_public     = 3;

  bytes          root_key                   = 4;
  uint32         previous_counter           = 5;

  Chain          sender_chain               = 6;
  // The order is significant; keys at the end are "older" and will get trimmed.
  repeated Chain receiver_chains            = 7;

  PendingPreKey      pending_pre_key        = 9;

  uint32             remote_registration_id = 10;
  uint32             local_registration_id  = 11;

  bool               needs_refresh          = 12;
  bytes              alice_base_key         = 13;
}

message RecordStructure {
  SessionStructure          current_session   = 1;
  // The order is significant; sessions at the end are "older" and will get trimmed.
  repeated SessionStructure previous_sessions = 2;
}

message PreKeyRecordStructure {
  uint32 id          = 1;
  bytes  public_key  = 2;
  bytes  private_key = 3;
}

message SignedPreKeyRecordStructure {
  uint32  id          = 1;
  bytes   public_key  = 2;
  bytes   private_key = 3;
  bytes   signature   = 4;
  fixed64 timestamp   = 5;
}

message IdentityKeyPairStructure {
  bytes public_key  = 1;
  bytes private_key = 2;
}

message SenderKeyStateStructure {
  message SenderChainKey {
    uint32 iteration = 1;
    bytes  seed      = 2;
  }

  message SenderMessageKey {
    uint32 iteration = 1;
    bytes  seed      = 2;
  }

  message SenderSigningKey {
    bytes public  = 1;
    bytes private = 2;
  }

  uint32                    sender_key_id       = 1;
  SenderChainKey            sender_chain_key    = 2;
  SenderSigningKey          sender_signing_key  = 3;
  repeated SenderMessageKey sender_message_keys = 4;
}

message SenderKeyRecordStructure {
  repeated SenderKeyStateStructure sender_key_states = 1;
}