In this part of article what is a Public Key Infrastructure Example (PKI Architecture) is to understand PKI functions. It executes two kinds of technologies: keys and certificates. A key is a long number used for the encryption of data. By utilizing the key formula, every element of a message is encrypted. Suppose you have some message to write where each letter is substituted by a letter after it, then, in that case, A becomes B, E becomes F, and so on. When someone has this key, they get a non sensual message that they have to decrypt.