Answer Description
PKI, or Public-Key-Infrastructure uses asymmetric encryption. There is a public key, and a private key, anything encrypted with a key can only be decrypted with the opposing key.
Wikipedia
Public-key cryptography, or asymmetric cryptography, is a cryptographic system that uses pairs of keys Each pair consists of a public key (which may be known to others) and a private key (which may not be known by anyone except the owner) The generation of such key pairs depends on cryptographic algorithms which are based on mathematical problems termed one-way functions Effective security requires keeping the private key private the public key can be openly distributed without compromising securityIn such a system, any person can encrypt a message using the intended receiver's public key, but that encrypted message can only be decrypted with the receiver's private key
Public-key cryptography - Wikipedia, the free encyclopedia