In cryptography, a public key is a cryptographic key that is used for encryption and is available to anyone who wishes to send a message securely. The key is derived from a private key, which is kept secret by the owner of the key pair.
When a sender wants to send a secure message to a recipient, they use the recipient's public key to encrypt the message. Once the message is encrypted, only the recipient with the corresponding private key can decrypt the message and read its contents.
Public key cryptography is widely used in various applications, including secure communication over the internet, digital signatures, and secure access control. The security of the public key cryptography system relies on the fact that it is computationally infeasible to derive the private key from the public key.
Overall, public key cryptography is an important tool for ensuring secure communication and data transmission in a variety of contexts.