RSA (Rivest-Shamir-Adleman)

RSA (Rivest-Shamir-Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission. Named after its inventors, Ron Rivest, Adi Shamir, and Leonard Adleman, who first publicly described it in 1977, RSA has become one of the most important algorithms in asymmetric encryption.

The Rivest-Shamir-Adleman (RSA) encryption algorithm is an asymmetric encryption algorithm that is widely used in many products and services. Asymmetric Encryption uses a key pair that is mathematically linked to encrypt and decrypt data.

A private and public key are created, with the public key being accessible to anyone and the private key being a secret known only by the key pair creator. With RSA, either the private or public key can encrypt the data, while the other key decrypts it. This is one of the reasons RSA is the most used asymmetric encryption algorithm.

The option to encrypt with either the private or public key provides a multitude of services to RSA users. If the public key is used for encryption, the private key must be used to decrypt the data. This is perfect for sending sensitive information across a network or Internet connection, where the recipient of the data sends the data sender their public key.

The sender of the data then encrypts the sensitive information with the public key and sends it to the recipient. Since the public key encrypted the data, only the owner of the private key can decrypt the sensitive data. Thus, only the intended recipient of the data can decrypt it, even if the data were taken in transit.

The other method of asymmetric encryption with RSA is encrypting a message with a private key. In this example, the sender of the data encrypts the data with their private key and sends encrypted data and their public key along to the recipient of the data.

The recipient of the data can then decrypt the data with the sender’s public key, thus verifying the sender is who they say they are. With this method, the data could be stolen and read in transit, but the true purpose of this type of encryption is to prove the identity of the sender.

If the data were stolen and modified in transit, the public key would not be able to decrypt the new message, and so the recipient would know the data had been modified in transit.

The technical details of RSA work on the idea that it is easy to generate a number by multiplying two sufficiently large numbers together, but factorizing that number back into the original prime numbers is extremely difficult.

The public and private key are created with two numbers, one of which is a product of two large prime numbers. Both use the same two prime numbers to compute their value. RSA keys tend to be 1024 or 2048 bits in length, making them extremely difficult to factorize, though 1024 bit keys are believed to breakable soon.