As technology increases, so do the methods of encryption and decryption we have at our disposal. The earliest messages used simple substitution ciphers, where you merely change one letter for another. Simple as it may be, it took nearly 1,500 years to crack them. World War II furthered the encryption by using carefully tuned machines to randomize the substitutions. Meanwhile, American forces in the Pacific theater utilized Navajo code talkers, choosing to use another language as a code. When substitution ciphers began to lose their charm, mathematics took over, creating nearly unbreakable encryptions. That is, until computing technology catches up.
Here, science journalist and author Simon Singh demonstrates the German enigma machine, a typewriter-like device used to encrypt communications. He demonstrates not only its operation, but both the strength and fatal flaws in its method.
More from this series: Keeping Secrets
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