  Quantum secure direct communication provides a direct means of conveying
secret information via quantum states among legitimate users. The past two
decades have witnessed its great strides both theoretically and experimentally.
However, the security analysis of it still stays in its infant. Some practical
problems in this field to be solved urgently, such as detector efficiency
mismatch, side-channel effect and source imperfection, are propelling the birth
of a more impeccable solution. In this paper, we establish a new framework of
the security analysis driven by numerics where all the practical problems may
be taken into account naturally. We apply this framework to several variations
of the DL04 protocol considering real-world experimental conditions. Also, we
propose two optimizing methods to process the numerical part of the framework
so as to meet different requirements in practice. With these properties
considered, we predict the robust framework would open up a broad avenue of the
development in the field.
