Ask HN: What hashing algorithm does goo.gl use?

It's not a pure hash; the same URL can be used many times to generate independent URLs. Using only the input of '<a href="http://google.com" rel="nofollow">http://google.com</a> generated the following URLs in a brief test:<p><pre><code> aw9RP fzUmL n4UNp V0Nre AYp1X OFw3w oQnRL RyICJ eMioQ sUcjC mzmKE i8NyH 42R3d 9XYcV 6KpEd TCve2 tzNUd pRMdn QbmDx WYaqH Ju74J gqmYd kilG8 AFe1P HiyI8 uqJal qj5mZ MzzwK WU8tK QJlwz vEqhL 1hdpl bBWCx CQgWq 3avus m8S7A ufJ4v YBlWF 7T4cX 1ypMQ 8zgUA Sslwf 9HTDt 7t8ji AqedO qyJNj 6rdR4 zRzcv 0wkJ9 Zmf4l rV5aK af7cE ix0TO bvNbb p4cKS m3vjc SXAnj DcLA2 JRwiP IdTQK</code></pre>

I assume they're just random numbers encoded in "base 62" or similar.<p><a href="http://birdhouse.org/blog/2010/10/24/base62-urls-django/" rel="nofollow">http://birdhouse.org/blog/2010/10/24/base62-urls-django/</a>