Key (cryptography)
Asymmetric algorithm: If there are two different keys, each of which can be used only to encrypt data or only to decrypt it, the algorithm is called asymmetric.  If an algorithm is asymmetric, one person publishes a key and accepts messages encrypted with that key.  Anyone can encrypt a message, but only the person who owns the other key can decrypt it.  This is how online stores, banks, etc., work.