One man’s fight for digital privacy

When cryptographer Phil Zimmermann created the world's most widely used email encryption software, US prosecutors sought to lock him up. David Crookes acts for the defence

- David Crookes

If you’re writing someone a personal message, I’m guessing that you wouldn’t be very happy if someone was taking a sneaky peek over your shoulder. It’s the same online, which is why most people want to protect their privacy. It’s also why many of us have come to love encryption software — tools that scramble readable data while it’s being transmitted so that only the intended recipients are able to view it.

But if it wasn’t for the efforts of activists and talented cryptographers such as Philip Zimmermann, there’s no telling what systems we would have in place today. For his is a story of strong principles, political will, technical brilliance, determination and innovation. Not to mention great courage and perseverance.

Born in 1954, Philip Zimmermann was ten years old when he became interested in cryptology. “I'd read a children’s book called Codes & Secret Writing and I learned about concepts such as substitution and transposition cipher while discovering how to make invisible ink out of lemon juice,” he told PC Pro.

He later began writing his own encryption programs at college. “I wrote a program to add random numbers to each letter of a message, using a pseudo random number generator. After sending the message, the recipient subtracted those same random numbers. It was completely, absurdly naive.”

As if to underline how much of a learning curve Zimmermann faced at the time, he came across one of the earliest textbooks about cryptography a few years later. The method of encryption he’d used in his college app was included as the focus for a homework assignment.

“I thought, ‘ah, great minds think alike’ and I felt so vindicated,” he said. “But then I came to realise, with a great deal of embarrassment, that developing this algorithm was not the assignment - breaking this algorithm was.