public key cryptography

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various techniques that use two different keys whereby data encrypted with one key can only be decrypted using the other. In typical use, the recipient makes one key public and keeps the other private, so that anyone may encrypt data for the recipient, but only the recipient can decrypt it.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The subfield of cryptography in which all information used to encode a message is assumed to be publicly available.