How does Instagram name files

Question

How does Instagram name files, are the file names random? based on some sort of hash? or is there some meaning to them? for example

http://distilleryimage2.instagram.com/21a9ca729bf511e2985c22000a1f9ad3_7.jpg

Answer 1

Good answer - The blog post is out of date now as their naming has changed, but it's probably still based on MD5.

Answer 2

After further inspection, I think it's just an MD5 hash or something followed by _# for the image size

Answer 3

Instagram uses an MD5 hash as the base name, followed by an underscore and a number representing the image size. Note that they probably don't just use file contents in their hash, as uploading the same image would possibly generate a filename collision, so they probably add in some entropy into their calculation.