Keeping same CID across clients

This is rather a client problem. For DC++-based clients, you can use the dcplusplus.xml file which would allow you to keep the same CID for another client.
Anyway, any respectable ADC should let you setup your own PID ( so CID as well ) from settings.
The work around you are proposing can only be helpful for ADCS ( secure ADC which would use such kind of certificates ). The problem still stands for normal ADC.
As I said, this is easy to settle on DC++ based clients.
The dcplusplus.xml should contain a field PID which in fact is the CID, that can be set... This problem no longer concerns DSHub as it is DC++ problem...

Thank you for your quick answer, that is rather useful information! However, I ran into some trouble trying to verify this because the CID of the client doesn't seem to be calculated in the same way as DSHub calculates it. Let's take dc++ as an example because it has a fields under EXPERT Settings where you can directly enter a PID/CID.
I look up my CID in DSHub with !info (by the way, there should be a way for all users to at least be able to get their own CID) and enter it in dc++. But when I then restart the client and log in again, I get a message "Nick reserved", meaning that my CID has actually changed.

So I enter in dc++: ADU6YHGCSUC6Z4NENLAZ64HWX4KTW3IA25HQDYQ
and DSH sees it as: UYFYDWG4XROQDZUQW57S2IJO3AD2WB3IMQCPQTY

Strange!

If you go to DC++ expert settings, what you are entering there is your PID. Your PID is used to calculate the CID and it's private.
You cannot enter your CID because your CID is generated by hashing the PID. You can set the PID and as a result you get a CID. So, DSHub can print your CID to anyone, bu the PID only to yourself. DSHub can show you your PID if you use the command +myinf even as an user.
And another thing, a respectable client should be able to show you your PID/CID pair ( DC++ isnt that respectable in this matter ).

So, what DSHub sees is the CID, and you were setting the PID.

Thanks a lot!!!