PKI

Public Key Infrastructure (PKI) is classicly the best security available to the general public. 

Public Key Cryptography was generally invented by the founders of RSA and was only available from that company until the mid 1990s when their patent ran out. 

Public Key Cryptography is also known as asymmetic encryption and uses a pair of cryptographic keys to encrypt and decrypt information.  An entity's public key is said to be publicly known while the compliment key, the private key, is nominally to be kept secret.   Any piece of information that is encrypted can only be decrypted by the compliment key.  So information encrypted with a private key can only be decrypted using the public key and vice versa.