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cisco dumps free download.Joker Figure 6-1 The Basics of Encrypted CommunicationThe two individuals, Batman and Robin, wish to establish a VPN connection between each other, and to do so, the two use digital signatures to authenticate each other's identities to ensure that the VPN connection is established between the correct entities. This concept is shown in Figure 6.2. Both Batman and Robin need to authenticate each other's identities, and for simplicity, focus on only one entity, Batman one-by-one - he has to prove himself to the oppositeend device (Robin) to prove his identity (it could also be argued that it is Robin who asks Batman to prove300 Chapter 6 Cryptography and Public Key Infrastructure (PKI) Fundamentals himself is Batman).Digital signatures (public keys)Figure 6.2 Digital signature verificationAs a little prearrangement, the reader should know that Batman and Robin not only generated their own public-private key pairs long ago, but both received digital certificates from a public certificate authority (CA). A CA is a trusted entity that issues digital certificates. This concept is shown in Figure 6.3.Digital Certificate Figure 6-3 Registering a Digital Certificate with a CAAs seen in Figure 6.3, Batman applies for (registers for a CA's) digital certificate from the CA, which issues a certificate to Batman. If the reader opens this digital certificate, they will find the name of the entity (in this case, Batman) and they will also see Batman's public key (the public key that Batman provided to the CA when he applied for the digital certificate). Figure 6.4 shows a digital certificate, which is a digital certificate for Cisco's Web site. The figure also shows the CA's digital signature.Note: Information related to CAs and the certificate registration process is covered in detail later in this chapter.