message GetTokenReqRaw {
    required bytes signature      = 1;
    required bytes key            = 2;
    required bytes attributes     = 3;
    required uint32 timeout       = 9;
}

message GetTokenReq {
    required GetTokenReqRaw req   = 3;
}

message GetTokenRetRaw {
    required int32 error          = 1;
    optional bytes token          = 2;
}

message GetTokenRet {
    required GetTokenRetRaw ret   = 3;
}