Many a times we've to ship 3rd party source code alongwith our code. The catch comes when the 3rd party assembly is an unsigned assembly while you have a strong need to sign the assembly being shipped by you.
If you try to refer an unsigned assembly into an assembly which is being signed then you get an error which says "Assembly generation failed Referenced assembly ‘xxx’ does not have a strong name"
The easy solution to this problem is to resign the 3rd party assembly using your key.
You can fing out how to do it on the blog by allkampfer on this link.
Happy signing :)