The First Book I Bought Was About Alan Turing

In my first semester studying computer science, in the year 2000, a course called Introduction to Computing gave one chapter to the history of the field – and one passage in it to Alan Turing. Most of my textbooks that year came free from the university book bank; I never had to buy them. So the first book I ever chose to spend my own money on was not a course book at all. It was a biography of Alan Turing. That impulse shaped more of my early career than any syllabus ever did.

// The Book That Started It

Alan Turing: The Enigma

Andrew Hodges

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A professor had told us the story. Not as a lecture, but as a story – the kind that stays with you long after the class ends. He spoke about the Enigma machine, about Nazi Germany's unbreakable cipher, and about the one man who looked at the "unbreakable" and saw a problem worth solving. By the time he finished, I had one question in my mind: where do I find the book?

The Machine That Was Called Unbreakable

Cryptography is, at its simplest, the art of creating secret codes – ensuring that only authorised people can read your information. Think of it as a lock and key for information. Cryptanalysis is the opposite: the science of breaking those codes, of finding the key when you were never supposed to have it.

During the Second World War, all German military communications depended on the Enigma machine – an electro-mechanical cipher device that scrambled every message through a rotating series of wheels and wiring. The Germans believed, with good reason, that the number of possible configurations was so vast that no human effort could ever crack it. They were right about one thing: no human effort could. It would take something more – a machine built specifically to think faster than human hands could ever turn a dial.

The Enigma machine was a work of genius. Only another genius like Alan Turing could break it.

Alan Turing built the Bombe – an electro-mechanical device that could cycle through the astronomical number of possible Enigma configurations at speed. It did not guess. It eliminated. It worked by logical deduction, exploiting known weaknesses in German operational procedure to narrow the search space until the day's settings revealed themselves. His contribution to the Allied effort is estimated to have shortened the war by two years. The number of lives saved is incalculable.

What struck me – and still strikes me – is that Turing did not just solve a problem. He invented the method of solving it. He saw that the answer required a machine, and so he conceived one. That is not engineering. That is something rarer: the ability to imagine a tool that does not yet exist and then build it.

The Fortunate Detour: Working in Cryptography

My fascination with cryptography was not academic for long. In my studies and in the early years of my career, I was fortunate enough to find an opportunity at a company working directly in cryptography and digital security. I had not planned for it. It found me – or perhaps the biography had quietly positioned me for it.

The piece I am proudest of from those years was something we called the data-wall service. Its one job was to take anything sensitive – a card number, a name, a phone number, a CVC, a PIN – and hand back a meaningless token in its place, so the real value never had to travel through the rest of the system. Underneath it sat public-key cryptography and a rotating session key, with one operational discipline that taught me more about real-world security than any lecture had: the encryption key changed every single day. A token minted last Tuesday still had to be readable today, so we kept the entire history of rotated keys, carefully, indefinitely. And because every other application in the company – back end, batch jobs, front ends – called the data-wall to protect its secrets, this one service quietly carried the trust of the whole payment ecosystem. Designing something that load-bearing, and that unforgiving, is where the standards stopped being reading material to me and started becoming a craft.

Most of my work there involved writing Java code capable of parsing, forming, and exchanging information within highly structured message formats. These were not arbitrary formats. They were governed by two families of international standards: Public Key Cryptographic Standards (PKCS) and RFCs – Requests for Comment, the documents that define how the internet actually works at its most fundamental level.

Working with these standards was humbling and illuminating in equal measure. The work itself was unforgiving in a way I came to love: when your implementation disagreed with the document, the document was right. Every byte order, every padding rule, every encoding decision had already been made by someone who understood the stakes – your job was fidelity. You quickly understood that the digital security everyone takes for granted – the padlock in the browser, the encrypted message, the secure login to a bank – is the product of decades of careful, collaborative, sometimes contentious work by some of the best minds in computer science.

The Rulebooks Behind Your Digital Security

Alan Turing's initial work created a baseline – a proof that mathematical reasoning could be mechanised, that complexity could be defeated by structured method. The generations that followed him built on that foundation to formalise cryptography into the standards that govern digital life today.

A Field Guide to the Shelf I Worked Against

Two families of documents governed everything we built. RFCs define the protocols – the foundational agreements of the internet; not laws, but something more durable: consensus among engineers who understood the stakes. PKCS defines the keys themselves – how they are generated, stored, exchanged, and protected. The full catalogue runs to thousands of pages. These are the ones I lived inside:

What Turing Started

Now, in every digital interaction you have, you can trace a line back through these standards to the problem Turing was trying to solve in 1940. The SSL padlock in your browser – TLS, PKCS #1, SHA. The password manager securing your credentials – PKCS #5, HMAC. The SSH connection your developer opened this morning – RFC 4251, elliptic curves, digital signatures.

Turing did not write RFCs. He did not design PKCS. He died before these standards existed. But he proved that secrecy could be broken by systematic method – and therefore that secrecy, to survive, had to be made formally rigorous. Every standard in this field is, in some sense, an answer to what Turing demonstrated was possible.

I am grateful I bought that biography that first semester; it gave me a reason to care about the field before I understood how much of the world would come to depend on it. Years later I watched Enigma, and then The Imitation Game more times than I can admit – it remains one of my favourite films, and the performance at its centre is extraordinary. But the fascination started on a page, long before any screen.