Public key cryptography has thus far become one of the cornerstones of secure communications in today’s digital age. It’s based on a two-key model. The public key is meant to be available to everyone, the private key is meant to be kept private. This decentralized system gives everyday people and social movements the technology to communicate quickly and securely online. It prevents anyone other than the intended recipient from decrypting the data.
The RSA algorithm is named after its inventors, Ron Rivest, Adi Shamir, and Leonard Adleman. This seemingly illogical and otherwise arcane algorithm forms the basis of public key cryptography. This particular algorithm helps keep sensitive information, like your private health data, protected while enabling the work and play of e-commerce, web-based email, and so on. Its importance to the security of the modern internet is hard to overstate.
Public key cryptography builds upon an area of mathematics called trapdoor functions. These functions are very simple to calculate in one direction but almost impossible to go back the other way without the private key. The current mechanism is based around multiplying two very large prime numbers, a job that is computationally trivial. As long as these prime numbers are kept secret, the encrypted message is protected.
Additionally, public key cryptography was developed over the period from 1970 to 1974. British mathematicians, mainly at the U.K. Government Communications Headquarters, initially developed this revolutionary idea. Russell Impagliazzo, a computer scientist and cryptography theorist at the University of California, San Diego, made a remarkable observation. Until computers came on the scene, trapdoor functions had no practical utility.
In 1976, Whitfield Diffie and Martin Hellman came up with the first known public key cryptography scheme. Their pathbreaking work was based on Ralph Merkle’s earlier theoretical concepts. These underlying concepts laid the groundwork for this groundbreaking method of trusted communication. That collaboration eventually became one of the most important developments in the history of cryptographic techniques.
Public key cryptography lets us create digital signatures. These signatures serve as mathematical evidence that a message originates from the owner of a private key. This ability is fundamental for authenticating the identities of senders and in turn safeguarding message integrity.
Meet your enemy spy, Boris. He has to get a secret message through to his new counterpart, Natasha. Boris composes his message and uses a special invisible ink with two ingredients: one that makes the text disappear and another that makes it reappear. This analogy is not perfect, but it is useful to illustrate the complex processes of encryption and decryption at work with public key cryptography.
“If a spy named Boris wants to send his counterpart Natasha a secret message, he writes a message and then uses the first ingredient to render it invisible on the page.” – (unspecified speaker)
The security of this whole system, which is based on public key cryptography, rests on protecting that private key. An unauthorized party getting access to this key would be catastrophic. They might break sensitive communications and undermine the whole security model. As a result, keeping this information secret is extremely important for the people and businesses that use encrypted modes of communication.
To keep up with technology’s rapid advancement, the field of cryptography must constantly innovate alongside it. The perpetual arms race between ever-more-complex algorithms and ever-more-powerful keys has made public key systems more secure every year. Given the growing sophistication of cyber threats, these accomplishments are especially important.
