Public-key encryption
Public-key encryption is a special encryption method, employing two passwords instead of one. One is password is given out to public - it is used to encrypt the data. The other password, a private one, is remembered by the party, which needs to decrypt the data. Only a file, encrypted with a public key, related to the private key, can be used to decrypt data to be decrypted by the private key.
Though public and private keys are related and must be used together, it is impossible to deduce a private key from a public key. One of the drawbacks of such encryption method is that a person, who needs to encrypt data to another person, needs to request a public key first, which may not be very convenient,