Citestyle in BibLaTeX with self-given style

I’m using Biblatex (with biber exectuion) for my citing.

I’d like to set the citation style such, that a from me given letter+number combination is visible in the text, likes so:

This is the text in latex with a citation [AB123]. Another citation to this could be [BCA124].

Also the bibliography style should then show this same letter+number combination:

[ABC123]  Authorname, Title, etc...
[BCA124]  Authorname2, Title2, etc...

Since sorting is not easily done that way, it would be a nice extra feature, if the bibliography would be sorted by their upcoming in the .bib file.

I hope my question is clear, since I can’t really put this into words.

documentclass{article}
begin{filecontents}{alphtest.bib}
@article{article1,
author={AuthorA},
title={title},
label = {ABC123}
}
@article{article2,
author={AuthorB},
title={title},
label = {BCA124}
}
end{filecontents}

usepackage[style=alphabetic]{biblatex}
addbibresource{alphtest.bib}
begin{document}
cite{article2}, cite{article1}

printbibliography
end{document}