Should I expose a user ID to public?

I have a form that reveals user IDs to public. I was wonde开发者_JAVA技巧ring that is this dangerous. Personally I do not see anything bad about it. The ID is just used to reference a single database record.

If it were dangerous, Stack Overflow wouldn't be displaying user IDs in their URLs in order to make user profile lookups work: https://stackoverflow.com/users/104826/rfactor

Edit of seriousness of immense levels: if user IDs are themselves sensitive data; for example your primary keys for some reason happen to be social security numbers, that'll definitely be a security and privacy liability. If your user IDs are just auto-increment numbers though, you're clear.

Generally it's not a problem but it can give away hints on how active your site is, like how many users you have etc. If you consider this sensitive information or maybe even good marketing is completely up to you.

There's a story that this was one of the reasons the germans lost the WW2. They had sequential serial numbers from production written on each tank. By collecting id numbers from tanks taken out the british could estimate how many tanks the whole german army had and make new strategies from that.

I have found that exposing primary keys that identify physical entities can create headaches.

Imagine if two blood samples come into a laboratory and test results are generated for each sample. Many different kinds of test might be done and each record representing a test result will have the sample_id as a foreign key.

If you share the database ID with the customer and you discover that two samples were accidentally switched, you will have to update the foreign keys in all the detail records representing the tests. If you instead exposed some other unique name outside your system, you will just need to switch the two unique names on the sample records in the master table.

There are other advantages related to data migration and there are advantages when entities are represented in more than one database in which it is difficult to create records with identical database ID's.

In my experience it is always best to expose a unique identifier other than the primary key outside your system. It gives you more flexibility in resolving data mix-ups, dealing with data migration issues, and in otherwise future-proofing your system.

as For me ID is as dangerous as showing user name.

Exposing an user ID is not, in and of itself, bad. It depends on the level of privacy and security needed. If the user ID does not expose and cannot be tied to any other personal data that should otherwise be private, it may not be a problem.

But don't think that public user IDs can never be a problem.

Make sure you don't allow anyone to break in to any private data just by knowing user IDs. Facebook has had problems like that. Here's just one example. While revealing user IDs wasn't the whole story, it was part of the equation.

Will it hurt anything? Only you can decide that, and you should think that through. But in general, it is poor form to display the User ID without having a business reason to do so. (Saves you work is probably not a good business reason.)

If it is a generated database id with no other meaning, it's not dangerous. Though I don't think revealing an id is elegant either. It's a technical detail and I can't understand why you would like to show it to users.