Public Key Cryptography

Public Key Cryptography

Author: BBC World Service March 11, 2017 Duration: 9:13

Take a very large prime number – one that is not divisible by anything other than itself. Then take another. Multiply them together. That is simple enough, and it gives you a very, very large “semi-prime” number. That is a number that is divisible only by two prime numbers. Now challenge someone else to take that semi-prime number, and figure out which two prime numbers were multiplied together to produce it. That, it turns out, is exceptionally hard. Some mathematics are a lot easier to perform in one direction than another. Public key cryptography works by exploiting this difference. And without it we would not have the internet as we know it. Tim Harford tells the story of public key cryptography – and the battle between the geeks who developed it, and the government which tried to control it.

(Photo: Encryption algorithms. Credit: Shutterstock)


Behind every price tag, spreadsheet, and market fluctuation lies a human story of curiosity, accident, and sometimes sheer stubbornness. In 50 Things That Made the Modern Economy, the BBC World Service presents a journey through the seemingly ordinary objects and concepts that quietly built the world we live in. Host Tim Harford goes far beyond dry economic theory, digging into the surprising origins of things like the plow, the bar code, or the limited liability company. Each episode unpacks how a single invention or idea rippled out, reshaping work, society, and global power structures in ways we rarely stop to consider. You’ll hear how the humble receipt fueled commerce, how the shipping container erased distances, and how double-entry bookkeeping enabled empires. This isn't just a history lesson; it's a series of detective stories that connect the dots between a tangible thing and the abstract forces that govern our daily lives. The podcast makes the invisible architecture of our world visible and compelling, revealing the economic fingerprints on everything from your smartphone to your supermarket shelf. Harford’s engaging storytelling transforms complex topics into accessible and genuinely fascinating narratives, reminding us that the modern economy wasn't built by abstract forces alone, but by concrete things dreamed up by people. Tune in to understand not just how the economy works, but how it came to be.
Author: Language: English Episodes: 100

50 Things That Made the Modern Economy
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