Public key cryptography, also called asymmetric cryptography, uses a key pair: one public key that can be shared and one private key that must be kept secret. The public key can encrypt data for the owner or verify a digital signature, while the private key decrypts or signs. This design supports secure communication without first sharing a secret key.
It is foundational to cybersecurity because it powers TLS connections, certificate-based identity, code signing, and many authentication systems. Attackers target it indirectly by stealing private keys, abusing weak certificate validation, or exploiting trust in compromised PKI infrastructure. Defenders rely on it to prove identity, protect transport sessions, and verify software integrity. It also matters in post-quantum planning, because many widely used public-key algorithms may need to be replaced or augmented to stay secure against future attacks.