I have been trying to figure out this use case, unfortunately without success:
A person logs into a portal (client's own portal, nothing to do with any of the Salesforce platforms) and they have the ability to manage their Marketing Cloud subscriptions.
There is no possibility to develop API calls - let's just say this must be a cost-effective solution, so we would like to include a Marketing Cloud Subscription Center link in the panel that the person sees after logging in. This link could be generated based on their Salesforce 18-digit ID or Email Address. The mysterious part is, how is the query string built and encrypted for use with Subscription Center?
I've been looking into the SFMC standard Subscription Portal links, and they all have a 128 character query string:
I suppose the query string must be the SubscriberKey or ID encrypted, but I wasn't able to decrypt it using any of the regular AMPscript functions.
The Subscription Center Link itself seems to contain a 64 character query string:
%%[
set @link = concat("%%subscription_center_url%%")
]%%
<a href="%%=RedirectTo(@link)=%%">click</a>
/subscription_center.aspx?qs=dfb1e5f836055bec5e7c1497c44f9b76af1c73eabe14feab3f3e66631e9d0000
So basically, my question is, how do I generate a correct query string for use with the Standard Subscription Center, given that I have access to that person's 18-digit Salesforce ID or their Email Address?
EDIT
OK, taking into account Johannes' and Don's comments, what would be a valid workaround?
I don't mind creating an automation to generate those links and update contacts/leads in Sales Cloud, so that every Contact/Lead has their own link that we can then feed to the external portal.
I am aware that this would not be a problem with a custom subscription centre, yet here we need to use the standard one.