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Note: When identicons were regenerated network-wide, all the "default" identicons were replaced — seemingly at random (e.g., a user on, say, 3 sites with 4 different identicons — including the network profile). However, I'm still wondering if there's an explanation for why this originally happened.


Why do so many users have an identicon without a hash value (i.e. use the default identicon)?

I realized at some point that I kept seeing users with the same identicon. At first I brushed it off, but since I started noticing this, I've seen dozens of users with this same picture. I checked some of them out and concluded that they have to be different people, based on differences in their profiles, what sites each account is active on, and even the quality of their writing. There's also the matter of the sheer number of such accounts as there are almost three quarters of a million users with this avatar on Stack Overflow alone. (It is the most popular profile image.) The only thing that these users seem to have in common is that their accounts are pretty old (or so I thought) and they all have this same image. (In fact, when this image shows up in the new users list, it's always someone with another, much older account on a different site.)

The image is this teal and white one:

Notably, the url for this is https://www.gravatar.com/avatar/?s=128&d=identicon&r=PG&f=1 (or similar, since some use a different size). Normal users have avatars like https://www.gravatar.com/avatar/123abbbbbbbbbbbbbbbbbbbbbbbbbbbc?s=128&d=identicon&r=PG (as an example). The obvious difference between these is that the second one has a MD5 hash (the 32 character hexadecimal string, which starts with 123 in my example) and the first one does not. This isn't answered by How is the default user avatar generated? because from that I would assume every profile should have a hash (no matter if the identicon was created before or after salting was started).

I'm just really curious now. Why did so many users get the identicon without a hash?


Examples:

  • abx
  • amrocs
  • user32882 (on GIS but not Stack Overflow)
  • jposor (on Stack Overflow but not their other sites)
  • Two users at Picnic
  • Three of four answerers for a certain ELU question
  • Many new staff members, such as tanj92, who joined in early 2022. In fact, it seems like all new staff members who haven't set a profile pic look like this. This, however, makes sense to me because their personal information is protected even from moderators. (Note: even after the regen, some staff still have this generic image on their network profiles.)

Not an example, uses an Imgur uploaded version:

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  • 3
    Looks a bit like Null island ...
    – Glorfindel Mod
    Commented Jun 5, 2022 at 18:14
  • PascalVKooten's profile picture is i.sstatic.net/hGOuLh.png, so I guess it's not a generated identicon (although it's the same image). All the others share the same (identicon) image source though.
    – 41686d6564
    Commented Jun 5, 2022 at 18:18
  • Does this answer your question? How is the default user avatar generated?
    – bad_coder
    Commented Jun 5, 2022 at 18:41
  • 3
    @bad_coder Already mentioned in my question. I don't see anything there that explains why the hash would be missing entirely.
    – Laurel
    Commented Jun 5, 2022 at 18:44
  • 3
    Only "a few" identical profile image urls: data.stackexchange.com/stackoverflow/query/1602299 ...
    – rene
    Commented Jun 5, 2022 at 18:50
  • 2
    I expect something at Gravatars end where users can select "no identicon"? That at least would explain the urls without an uuid/hash
    – rene
    Commented Jun 5, 2022 at 19:01
  • 7
    @bad_coder the point is: there is no hash. Forget your bla bla about functions, salting and collisions. There is nothing ...
    – rene
    Commented Jun 5, 2022 at 19:09
  • 1
    Does this answer your question? Unexpectedly changing identicon - if you choose Identicon, but don't have a Gravitar account; you only get the salted hash.
    – Rob
    Commented Jun 5, 2022 at 19:14
  • 1
    @bad_coder Where is that even mentioned in the linked post? Usually, when someone mentions how they didn't find an answer in a related post and you think that the same post does answer their question, it's nice to explain how you think so along with your vote to close as duplicate (unless it's something really obvious). A standard auto-generated "does this answer your question" comment is borderline rude in this case, in my opinion.
    – 41686d6564
    Commented Jun 5, 2022 at 19:19
  • 1
    @Rob Nope! There's no mention of the image I'm seeing and in fact both of the images there have hashes. Also, many of the users who have this image were created after images began to be salted. As has been mentioned already, the image I'm asking about doesn't have a hash, so it can't possibly be salted.
    – Laurel
    Commented Jun 5, 2022 at 19:21
  • 2
    Just another nail in Gravatar coffin, SE really really really must drop this and stop supporting it, it's bad, full of bugs, and I'm sure full with security holes as well. Should be simple enough to import all existing Gravatar images in use to imgur and just don't let user choose such option anymore. Commented Jun 5, 2022 at 19:42
  • 1
    @Laurel ok, my issue then is: in your question (unless I'm mistaken) there are at least 2 users whose identicon leads to an URL without a hash, right? There's no magic there, behind an URL without a hash sits that 1 identicon (probably it's the default?!). Now, can you have another URL with a hash that gives the visually identical (I didn't check the images programmatically to ascertain if the similarity is only apparent or exact) image? Yes sure... Then, if the question is: how did it get to that? I do think the link dup targets more or less address the business process.
    – bad_coder
    Commented Jun 5, 2022 at 20:06
  • 3
    I'm really not sure what you're asking here. The reason these users have the same identicon is because for all of them the identicon is being fetched without specifying a hash, so the default is used, for all of them. However, you've already identified that. So what are you really asking? Are you really asking "Why is no hash used for the identicon on a lot of users?" If so, then there's not going to be much more of an answer other than "when their current identicon was semi-permanently assigned, no value for the hash was used/available" (which will have multiple possible causes).
    – Makyen
    Commented Jun 5, 2022 at 22:20
  • 2
    Hopefully the four of us (you, bad_coder, me, and Makyen) agreeing that the URL (that is 'blank' ) is what is used to create the Identicon satisfies this question. - The additional fields are blank, thus it's all seen as the same user; much as if the additional fields were filled in with identical information, and that would be thought to be the same user (even if it's not) - thus all creating the same image.
    – Rob
    Commented Jun 5, 2022 at 23:36
  • 12
    I'm asking why the URL is blank, so saying that it's blank doesn't answer my question :l
    – Laurel
    Commented Jun 6, 2022 at 16:08

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