How to add random code in a link?

I have a link on my website which I post in almost every post and which is like this http://ift.tt/2k5FjXc . where "abcde" and "12345" is a random test which I am currently adding myself. I need your help to make the "abcde" and "12345" random text to generate automatically in the link so that I don't have to add them by my self. the middle code "AdJ8YEZAdd4ubfbW4Aztw2Ur" is the main code

thank you very much, looking forward to receiving any help.