[corytheboyd]

You as a user of Amazon can do whatever you want though, including being careful about which pieces of information you elect to expose publicly. If it’s up to you, why choose to expose it, when you can choose NOT to? Just because this reverse search of bucket to account id exists doesn’t mean you should begin to expose your account id on your own.

[evandale]

You can't choose NOT to expose it because you can't stop Amazon from exposing it.

Amazon says it's not secret, so it's not secret. They make no attempts or guarantees to keep it secret so there's always the threat that Amazon themselves can expose it on your behalf. You can't stop that no matter how wrong you think it is.