message.proto

syntax = "proto3";

message MessageWrapper {
  // 128-bit initialization vector for the AES-256-CBC algorithm. Can be
  // an empty string, in this case we assume that the message is not
  // encrypted.
  bytes aes_init_vector = 1;

  // Possibly encrypted binary representation of the Message proto.
  bytes message = 2;
}

message Message {
  oneof payload {
    DataOperation data_operation = 1;
    Info info = 2;
    SessionKey session_key = 3;
    RsaPublicKey rsa_public_key = 4;
  }
}

message DataOperation {
  enum Type {
    GET = 0;
    UPDATE = 1;
    DELETE = 2;
  }
  // Type of the operation. Set by the client, not set by the server.
  Type type = 1;
  bytes key = 2;
  bytes content = 3;
  // Initialization vector used to encrypt the content of the message. The
  // client's secret key, which is not known by the server, is used as an
  // encryption key in this case. Necessary for client to decrypt the content
  // after receiving it from the server (the client doesn't save this
  // initialization vectors).
  bytes content_encryption_init_vector = 4;
}

message Info {
  enum Status {
    OK = 0;
    DATA_NOT_FOUND_ERROR = 1;
    NO_VALID_SESSION_KEY_ERROR = 2;
    NO_VALID_RSA_PUBLIC_KEY_ERROR = 3;
    MESSAGE_CORRUPTED_ERROR = 4;
    UNEXPECTED_MESSAGE_ERROR = 5;
    INTERNAL_SERVER_ERROR = 6;
  }
  Status status = 1;
  string description = 2;
}

message SessionKey {
  bytes encryption_key = 1;
  int64 expiration_time = 3;
}

message RsaPublicKey {
  bytes key = 1;
}