Rhodri Marsden: When it comes to saucy pictures, trust no one. Least of all yourself

The case of John Schindler is a curious one. A former NSA analyst and, until recently, a professor at the US Naval War College, he resigned on Tuesday following a college investigation into whether a widely circulated picture of his penis was actually his.

In May, as part of a consensual text message exchange with an unnamed woman, a man alleged to be Schindler sent a picture of his penis. She replied, expressing surprise at its size. That exchange was screengrabbed by the woman and leaked on Twitter shortly afterwards.

As a consequence of this, Schindler is no longer in his post, and it prompts a number of questions. One of them is why a former NSA analyst who presumably knew a bit about operations security would have allowed himself to be put in such a position. Another is why Schindler felt forced to resign. Yes, the world may have seen his penis, but he wasn't the one who showed it to us. Perhaps, as a married man, his implied infidelity was frowned upon by his employers, but without the penis furore it probably wouldn't have been such a big deal.

There was another recent case in Savannah, Georgia, where pupils gained access to a female teacher's phone and enthusiastically shared her naked photos online. Again, the teacher was dismissed from her post, presumably unable to continue because people had seen her breasts. But the moral judgements being made are lacking in consistency. Another teacher in Pasadena recently went unreprimanded after his email was hacked and naked photos of him were sent to friends and colleagues.

A specific law was passed last year in California to prohibit the dissemination of sexually explicit photos belonging to someone else, and that may have persuaded his employer that he was the victim of a malicious act. But so was Schindler, and so was the teacher in Savannah. "Revenge porn" is a term used to describe disgruntled ex-partners posting naked pictures online, but all these cases amount to the same thing. Your privacy has been maliciously compromised, and it's not your fault.

"Oh, it certainly IS your fault," I hear people cry, people who view the taking of intimate photos with the same disdain as they view zoophilia. But such pictures exist for one of two reasons. Either someone has been placed under pressure by their partner (a horribly insidious form of control) or they've done it willingly, driven by sexual impulse. Long gone are the days where people would take a Polaroid of their own genitals, wave the picture around for a bit, watch it develop, look at it, pop it in an envelope and wander down to the postbox. That gave time for reflection. Today, we live in an age of instant, technology-driven gratification, and while no provocative snaps of me exist, I wouldn't blame anyone for succumbing to the temptation.

But having succumbed, your pictures will lie around in digital form. There must be millions upon millions of lewd snaps across the globe, sitting on email servers, phones, tablets, laptops, cameras and so on.

Given that data is never as safe as we think it is, that adds up to a whole heap of brooding anxiety as we ponder the motives and future actions of anyone we share intimate moments with. The woman who quite literally exposed Schindler explained that she only "wanted to inform his wife and embarrass him". In some parts of the world, she'd have broken the law, but Schindler's the one paying the price for misguidedly placing his trust in someone. The moral of all this is probably "trust no one, least of all yourself". And that feels like an unpleasant place for us all to be sitting.