Decode ObjectSID from Base64-encode string

Hi,

I have APM policy that I try to retrieve the user ObjectSID from Active Directory.

The problem is that the APM give this object in Base64-encode string and not in it original format.

Is there any  way to decode it in the APM policy or iRule so I’ll get it at the end of the APM policy in it original SID format?

eg

I get it in the policy as AQUAAAAAAAAT1QZ9BTHHd5jj1Isdb88A==

and I want the original SID format, such as S-1-5