an hex formated SID value (e.g. 0x151552dabe9d1ce4e8dd6b635f23d4c). Perl seems to be converting this to ascii and ends up outputting garbage

An "hex formmatted SID value" is a string, so you're confused about something.

(To make matters worse the garbage includes random tabs and carriage returns).

Well, your code includes lots of "\t" in places, so you need more Basic debugging checklist item 4 ( Dumper ) to find out what kind of data you really have, and how to format it the way you want