RSA is the cryptographic algorithm named after Ron Rivest, Adi Shamir, and Leonard Adleman.
The three researchers published the system in 1978, building on public-key cryptography concepts developed in the 1970s. RSA uses a mathematically linked public key and private key. Anyone can use the public key to encrypt information, while the private key is kept secret for decryption or signing.
Its security relies on the practical difficulty of factoring the product of two very large prime numbers. RSA became an important technology for digital signatures, certificates, and secure key exchange, although modern systems often use it mainly to protect a symmetric session key.
RSA is named from the inventors’ surnames, not from a technical phrase. The algorithm is different from symmetric ciphers such as AES, which use the same secret key for encryption and decryption.