An Iranian living in the U.S. called a friend of mine who lives here in New York and said, "I see on my caller ID that you tried to call me. What's it about?" As you've no doubt guessed from the title of this post, my friend had done no such thing. A few weeks later, the same thing happened with another Iranian living in the U.S.In both cases, it turns out that Iranians living in Iran had used spoofing technology to disguise their phone numbers in order to call friends or family living here.

The fact that they used my friend's number is purely a coincidence.

Why did they do this? It's a smart way to avoid having their numbers show up as calling the U.S. -- an offense I've been told is grounds for arrest.

What's that got to do with fake Twitter accounts, other than fakery is involved?

The issue all of us are now facing -- not just Iranians living in repressive regimes and Americans living in an overly sensationalized and media personality-driven culture -- is what to trust in a digital age.

Here are a couple of other scenarios I've been forced to ponder in the past few days:

what if I buy a digital book purporting to be 1984 by George Orwell, in which a truly benevolent Big Brother marries Winston Smith to Julia? what if I buy an MP3 called "Revolution" by John Lennon in which the lyrics are, "but if you want money for minds that hate, brother you know that you've got my weight?" what if I receive a Tweet linking to a video of Barack Obama in the East Wing declaring that we're about to use nuclear weapons against China? Cybersecurity expert Melih Abdulhayoglu, CEO of Comodo, tells me that content authentication is "the next big thing." According to Abdulhayoglu, the infrastructure exists to authenticate content, and we're not taking advantage of that technology at enormous societal risk, because "there's a huge play in trust and how you manipulate it for ill gain." In the physical world, we rely on our five senses to inform us about reality, but that context doesn't exist online. "We are building a society that is totally dependent on digital content. At some point we are going to have a 9/11-like incident because of our reliance on digital data, because that data can't be trusted… All it takes is one credible source to push out something that people will trust without verifying -- a stock market could crash, anything could happen," he said. Sounds like a lot of what-if. But then someone calls you and swears you called them when you know you didn't, and the National Security Agency finds your denials suspicious. What then?