Biblatex cite 2 different sources for one paper as [Xa] and [Xb]

Question

I'm using biblatex with numeric style. I think about referring this both sources

This shall be a MWE

\documentclass{scrartcl}
\usepackage[backend=biber,%
                        bibencoding=ascii,%
                        style=numeric,% 
                        natbib=true,%                                       Lädt das Kompatibilitätsmodul, welches Pseudonyme für die Befehle der Literaturverweisregeln des natbib-Pakets zur Verfügung stellt.
                        maxbibnames=3,%                                 Es werden maximal 5 Namen in der Bibliographie ausgegeben
                        sorting=nyt,%                                       Name, year, title
                        giveninits=true,%                               Vornamen werden abgekürzt
                        uniquename=init,%                           Einzigartige Namen werden abgekürzt
                        isbn=false,%                                        Isbn wird nicht ausgegeben
                        doi=false,%                                         doi wird nicht ausgegeben
                        clearlang=false,%                               weiß ich nicht
                        maxcitenames=3,%                                    in Zitationen erscheinen höchstens zwei Autoren
                        urldate=comp,%
                        defernumbers=true%
                        ]{biblatex}
\RequirePackage{filecontents}
\begin{filecontents*}{\jobname-bib.bib}

@misc{Kim_Barbulescu-2016,
        author = {Taechan Kim and Razvan Barbulescu},
        title = {Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case},
        howpublished = {Cryptology ePrint Archive, Report 2015/1027},
        year = {2016},
        url = {http://eprint.iacr.org/2015/1027},
        urldate = {2017-03-20},
        keywords = {paper}
}
@Inbook{Kim_Barbulescu-2016b,
        author="Kim, Taechan and Barbulescu, Razvan",
        editor="Robshaw, Matthew and Katz, Jonathan",
        title="Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case",
        bookTitle="Advances in Cryptology -- CRYPTO 2016: 36th Annual International Cryptology Conference",
        year="2016",
        publisher="Springer Berlin Heidelberg",
        address="Berlin, Heidelberg",
        pages="543--571",
        isbn="978-3-662-53018-4",
        doi="10.1007/978-3-662-53018-4_20",
        url="http://dx.doi.org/10.1007/978-3-662-53018-4_20",
        keywords = "paper"
}
\end{filecontents*}
\bibliography{\jobname-bib}
\begin{document}
\nocite{*}
\printbibliography[title={Paper}, heading=subbibliography, keyword=paper]
\end{document}

Since those are both the same releases, I would like to list them as different sources highlighted by [Xa] and [Xb] (where X is a natural number)

My first question: Would you refer to both publications? How can I reach my intention?

Answer 1

If you want both entries to appear in the bibliography, you can use @set

@set{kimburb,
  entryset = {Kim_Barbulescu-2016,Kim_Barbulescu-2016b},
}
@online{Kim_Barbulescu-2016,
  author       = {Taechan Kim and Razvan Barbulescu},
  title        = {Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case},
  howpublished = {Cryptology ePrint Archive, Report 2015/1027},
  year         = {2016},
  url          = {http://eprint.iacr.org/2015/1027},
  urldate      = {2017-03-20},
}
@inproceedings{Kim_Barbulescu-2016b,
  author    = {Kim, Taechan and Barbulescu, Razvan},
  editor    = {Robshaw, Matthew and Katz, Jonathan},
  title     = {Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case},
  booktitle = {Advances in Cryptology -- CRYPTO 2016: 36th Annual International Cryptology Conference},
  year      = {2016},
  publisher = {Springer},
  address   = {Berlin and Heidelberg},
  pages     = {543--571},
  doi       = {10.1007/978-3-662-53018-4_20},
}

This comes very close to what you had in mind if you use the subentry=true option of the numeric styles.

---

But you could add Kim_Barbulescu-2016 as related entry in Kim_Barbulescu-2016b if you want:

@online{Kim_Barbulescu-2016,
  author       = {Taechan Kim and Razvan Barbulescu},
  title        = {Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case},
  howpublished = {Cryptology ePrint Archive, Report 2015/1027},
  year         = {2016},
  url          = {http://eprint.iacr.org/2015/1027},
  urldate      = {2017-03-20},
}
@inproceedings{Kim_Barbulescu-2016b,
  author    = {Kim, Taechan and Barbulescu, Razvan},
  editor    = {Robshaw, Matthew and Katz, Jonathan},
  title     = {Extended Tower Number Field Sieve: A New Complexity for the Medium Prime Case},
  booktitle = {Advances in Cryptology -- CRYPTO 2016: 36th Annual International Cryptology Conference},
  year      = {2016},
  publisher = {Springer},
  address   = {Berlin and Heidelberg},
  pages     = {543--571},
  doi       = {10.1007/978-3-662-53018-4_20},
  related   = {Kim_Barbulescu-2016},
}