They might've purchased a decryption key from some dark corner of the internet and after failing to trace the money to the bad-guy they're now hoping to track him down by IP address. Probably it would surface in court that you're not the bad guy they're after, but who knows what kind of bad things they'll do to you in the meantime.

They might own the legendary key that turns your seemingly random data into very illegal data.

plot twist: It's an one-time pad to xor your data against.

(and of course, they wouldn't generate it from XORing your data against illegal data...)

Well this is a terrifying idea. Is this a hypothetical or do we know of an instance where such a “key” was invented?

Most cop-tech is just plausible-deniability for jury who are not tech-aware. Dogs, polygraphs, informational pre-crime tools.

In around 1900 i think.

It's simple for anyone to create an xor "key" for anything.

I phrased my comment poorly. Do we know of a case where cops or prosecutors have actually faked such a “key”? If so, it’s terrifying that you could have any encrypted data, with cops and their invented xor “keys” claiming your data is whatever they want it to be.

Or that you could have unencrypted data, that cops could xor into illegal data.

I bet you’re just using those unencrypted images to hide evil stuff with steganography! We found illegal content by xoring our totally not invented xor "keys" with the noise in your JPEGs!

I don't know of any widespread consumer encryption tools that use a one time pad. For comparison, a standard RSA key is 4kb.

But how good is a phone call.... if you cannot speak.