A Minor Mystery

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You can find out more about the Maths Jam here:

You can sign up to attend (or just hear more about) the gathering here:

Recently I announced the Maths Jam 2014 Annual Gathering. I sent emails to everyone on a list, and to make it as easy as possible for people to opt-out of getting more missives, I included a link at the bottom. Some people have clicked on that link, and they'll never hear from me again. That's fine, that's expected, and it's made it easy for them, and easy for me.

The link looked like this:


The idea is that the code gets saved to a file, and then the entries in the file are checked against the email address in my list. This provides at least a small amount of protection, and is easy enough both to implement, and run.

Bizarrely, though, some people have clicked on a related, but different, link. Or they've clicked on that link, and their browser or email client have done something semi-random. Here's an example of something that got saved.


That's not in my list - that never got sent. In particular, it's not an md5 hash.

For reference ... I've now changed the program so that it removes any characters not in the range of (lower case) hex digits, and then only saves the result if it's exactly 32 characters long. That will prevent people from believing it got saved when it didn't, and it should mean that only valid codes get saved at all.
However, ... if we take the rot13 of it we get


and that's almost what I expect - it just has a few extraneous digits scattered throughout the interior.

How is this happening? Why is it that some people are happily clicking on the link and their hashes are being saved unmolested, while others get this bizarre mutation?

If anyone is interested and has an idea, let me know, because I'd love to get to the bottom of this mystery.

Please - email me.


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