"crypto" is the wrong word, public-private key systems are not used to encrypt, they are used to authenticate, the opposite of kruptos, Greek for ‘hidden’. This branch of asymmetric cryptography that was developed in the 1970s with the RSA system, is no longer about hiding, it is about putting information out in public, "publicography", and proving the legitimacy of transactions through mathematical signatures. Instead of making information secret, it is about making information known, authenticating it. The word cryptography is much much much older than public-private key systems, which are just half a century young, and only in the past decade have they begun to be used for proving ownership in a public context.
