[GauntletWizard]

I feel really okay with this, but I'm not okay with is that there isn't language to talk transparently about it. Facebook does the same thing (or did, because I haven't used Facebook in a long time), if you copy link to image, you can just forward that, even if the post is private.

This is pretty inherent in image sharing, though. You can just download the image, or if the website limits that you can take a screenshot (let's not get into the debate about DRM and assume that it doesn't work).

Where should you draw the line? Time limited link sharing? Login based doesn't work because you can't share with Grandma - she doesn't know how to login.

We need words and descriptions of these basic patterns, and better ways to Intuit which is in use.

[mrehler]

I think the phrase used here quite often is "security through obscurity" when it comes to links. The question is whether people feel comfortable with family photos falling under that principle. They're obviously not meant for public consumption, but the feeling of privacy invasion if a random person stumbled on them is going to vary from person to person. If one was totally comfortable with them being public and has zero reservations about random folks peeking on them, then I'd be surprised if there weren't an even sturdier way to do this publicly (through Flickr or just an open FTP link – but that loses some of the convenience of just an iCloud album for some people).

[GauntletWizard]

Securely-generated unique links aren't security by obscurity at all - They are literally the same as any password or private key being unique and high entropy. The security problem is inherent with any data that is shared widely.