The RSA cryptosystem is a family of public-key cryptosystems (one of the oldest), widely used for secure data transmission. The initialism "RSA" comes from the last-names of Ron Rivest, Adi Shamir and Leonard Adleman, who publicly described the algorithm in 1977.
How RSA Works
Messages are encrypted with a public key, which can be shared openly. With the RSA algorithm, once a message has been encrypted with the public key, it can only be decrypted by a private (or secret) key. Each RSA user has a key pair consisting of their public and private keys. As the name suggests, the private key must be kept secret.
- Key generation: The private key is a pair of large prime numbers. The public key is derived from the private key.
- Encryption: The sender encrypts the message with the recipient’s public key.
- Decryption: The recipient decrypts the message with their private key.
Applications of RSA
RSA is used in digital signature such as RSASSA-PSS or RSA-FDH, public-key encryption of very short messages (almost always a single-use symmetric key in a hybrid cryptosystem) such as RSAES-OAEP, and public-key key encapsulation.
- Digital signatures: RSA can be used to create digital signatures, ensuring the authenticity and integrity of messages.
- Secure data transmission: RSA is widely used for secure data transmission, including in protocols like TLS/SSL.
- Key exchange: RSA can be used to securely exchange symmetric keys, which are then used for encrypting and decrypting messages.
