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

MD5 collision is extremely unlikely. If you have 9 trillion MD5s, there is only one chance in 9 trillion that there will be a collision.