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: public keys (which may be known to others), and private keys (which may never be known by any 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