Public Key

In public key cryptography, a user is paired with two cryptographic keys - a public key and private key. The private key is to be kept confidential while the public key may be freely distributed. Though the keys relate on a mathematical level, a private key cannot be derived from the public key. Data encrypted by a public key can only be decrypted with that corresponding private key. The issue with this form of cryptography is proving that the public key is authentic. In many cases, intruders are able to modify the data or completely replace it with a new key. The most common approach to this problem is to use the PKI (Public-Key Infrastructure). PKI is a protocol in which a known certificate authority validates ownership of both keys. Another method used to ensure the authenticity of a public and private key is known as the Web of Trust.