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Don't Put Personal Information in Code!

jdsteinhauser profile image Jason Steinhauser ・2 min read

Normally, I wouldn't cringe during a code review when I see

var testValue = 716.1976;

BUT when I include the rest of the line...

var testValue = 716.1976;      // Carl's birthday

Well, then I start to question what in the world you were thinking! (Note: some names and dates have been changed to protect the innocent)

Most online tutorials involving DevOps or API keys will warn you to not include keys and passwords in your repo; those are the sort of things that are best relegated to environment variables (or some other secure method). But usually you don't come across tutorials warning to exclude Personally Identifiable Information (PII).

What is PII?

In short, PII is anything that you can use to figure out who somebody is. You usually hear it in identity theft discussion. Several things are included as PII, such as:

  • Birth date
  • Home city
  • Social Security Number (in the U.S.)
  • High school
  • Location of birth

You know all those security questions for password recovery? Yeah, all of that is PII.

What can you do with that?

Well, there are several websites that, given a few tidbits of your personal info, can be used to find out all sorts of things. Current and past addresses. Names of relatives. Former/maiden names. All with a few simple keystrokes on Pipl or Intelius and you can find a lot of information.

Going back to the comment that started all of this, I didn't have a surname for "Carl," but I did have the developer's last name thanks to a comment block at the top of the file (not to mention, a commit history). A quick search got me his address, Facebook profile, occupation (a nurse!), and an age that corroborated his birthday in the code.

Did you send "Carl" a birthday card?

I totally did... in my mind. But then, I played through how freaky that would be for Carl, and how mad he would be at "Lucy" despite no ill intentions. I didn't want to fracture any relationships solely to make a point... But "Lucy" is now well aware of the ramifications.

Is this an isolated incident?

I know people that have hidden spouse's birthdays in code as "magic" or "test" values... but they've never explicitly stated that in comments like "Lucy" did. Has anyone else come across any issue like this before? How did you resolve it? And how would you have liked to resolve it?

Please don't use real names/info if at all possible!

Posted on Jun 4 '18 by:

jdsteinhauser profile

Jason Steinhauser


15+ years of analysis and development. Father of 3. Passionate about testing, functional programming, and pretty graphs.


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I agree that putting personal data into code is evil and comment near value which is explaining the meaning of value is even worse (we should use meaningful variables instead of commenting the value of a variable).

After I've read your article, I've started wondering how personal information in the source code are related to General Data Protection Regulation (GRPD) which came into force in Europe a few weeks ago? :)


I hadn't even thought about it from a GDPR standpoint yet! That's even more reason to avoid any sort of personal information in code. Thanks for bringing that up!