Asymmetric Encryption

Asymmetric encryption, also called public-key cryptography, solved one of the fundamental problems of symmetric encryption: how to securely exchange keys between parties who have never communicated before. With asymmetric encryption, each party generates a key pair. The public key can be freely distributed, while the private key must remain secret.

The most widely used asymmetric algorithms include RSA, which relies on the difficulty of factoring large prime numbers, and elliptic curve cryptography (ECC), which relies on the discrete logarithm problem over elliptic curves. ECC offers equivalent security to RSA with much shorter key lengths -- a 256-bit ECC key provides comparable security to a 3072-bit RSA key -- resulting in faster operations and lower computational overhead.

Asymmetric encryption serves several critical functions in modern security. It enables secure key exchange (allowing two parties to establish a shared symmetric key over an insecure channel), digital signatures (proving the authenticity and integrity of a message), and certificate-based authentication (validating the identity of servers and clients). However, asymmetric operations are computationally expensive, so they are typically used to protect small amounts of data such as session keys or message digests, while symmetric encryption handles bulk data encryption.