ABSTRACT
Perhaps the biggest challenge in public-key cryptography is ensuring the authenticity of public keys. If Alice wants to encrypt information to send to Bob, and Bob is someone who Alice does not know personally, how can Alice be sure that Bob’s purported public key really is Bob’s key (and not Charlie’s, for example)? We have already introduced certificates as a tool to help authenticate public keys. A public-key infrastructure (or PKI) is a secure system that is used to manage and control certificates.
