How many random elements before MD5 produces collisions?

Question

I\'ve got an image library on Amazon S3. For each image, I md5 the source URL on my server plus a timestamp to get a unique filename. Since S3 can\'t have subdirectories, I

Answer 1

So wait, is it:

md5(filename) + timestamp

or:

md5(filename + timestamp)

If the former, you are most of the way to a GUID, and I wouldn't worry about it. If the latter, then see Karg's post about how you will run into collisions eventually.