Ideas and inventions are not concocted inside of a vacuum. They grow from a wide array of preexisting knowledge and ideas already present in the scientific community from public contributions. However, there exists a break in this flow of information; as Singh points out in chapter 6 of The Code Book, government findings are often kept under lock and key. This was certainly the case for the work being done at England’s GCHQ in the 20th century. Researchers Ellis, Cocks and Williamson were working diligently on a solution to the problem of exchanging keys in the cryptographic world, and their findings culminated in a successful solution to their mission in 1973. But, because of the highly classified status of their work at the time, their discovery was unbeknown to the world until it was finally released almost 30 years later.
Meanwhile, without knowledge of the British intelligence, the same problem was being attacked by academics on the American front. On the West Coast, researchers Diffie, Hellman and Merkle theorized a solution to the key exchange problem by implementing asymmetrical ciphers. MIT scholars Rivest, Shamir and Adleman successfully implemented the idea in a working system that we still use today. The RSA encryption algorithm was officially patented in 1979.
So who are the true inventors of public key cryptography? Although the credit goes mainly to the men abbreviated by the letters R, S and A, I would argue that all of the parties deserve recognition. The combined efforts of both the British and American groups resulted in a successful solution to the problem at hand. Their discoveries took place six years apart, but the latter success did so without knowledge of the prior. Rivest, Shamir and Adleman secured a patent enabling them to claim the invention of public key cryptography, copyright laws are simply a social construct, so we cannot ignore the often classified contributions of those working in government.