RSA is an algorithm that is used in authenticating, encrypting, and decrypting digital information. It is named for Ron Rivest, Adi Shamir, and Leonard Adleman, the MIT trio of cryptographers and computer scientists who invented it. Digital information is encrypted on a public key and then decrypted using a private key.
For example, Alan uses his private key to send a message to Barb. The only way he can send it is through Barb’s public key. So Alan produces a cryptographic value of his message, which becomes his signature. To verify Alan’s signature, that the message is truly from him, Barb uses the same algorithm that she encrypts her private messages with to him, and that Alan uses with his public key for decrypting the private messages he receives. By comparing the encrypted values, Barb can authenticate that the sender was also using Alan’s private key and is therefore in fact, Alan.
The security of the RSA rests on the extensive mathematics involved – the use of long numbers and the mathematical problem itself, thus making full decryption unlikely. But because the RSA uses a determined algorithm, a randomized padding scheme is typically employed with it before encryption to safeguard against partial decryption threats. And while keys are usually 1024-2048 bits long, some experts question the feasibility of maintaining the future security of shorter bit keys, recommending that they be at least 2048 bits long.