Symmetric keys provide the fast encryption standards needed by today's applications; however, these keys need a method for exchange over an unsecured network. PKI provides a solution to this challenge.
A and F
Because of its speed, symmetric encryption is a good choice for real-time encryption of bulk data. This speed is achieved because the encryption key is the same as the decryption key.
D and F
The trusted introducer and its clients must trust the root of a system. The root guarantees the identity of the trusted introducer. Only the trusted introducer can guarantee the authenticity of any member of the system.
A certificate includes the identity of the issuer of the certificate, the identity of the owner of the certificate, and the public key of the owner.
C and F
Securing enrollment through a PKI can be a sticky situation. The best method is to perform the enrollment over a trusted network (or significantly secured public network). Otherwise, you must manually perform mutual out-of-band authentication between the PKI user and CA.
Certificate revocation is needed whenever the private key is not trustworthy anymore. This can occur through a loss of the private key (from a system rebuild or replacement), or a malicious compromise of the private key (from an intruder).
The web server certificate is used to authenticate the server to the client and to encrypt the symmetric session keys used for the authentication and encryption of the data stream.
The Diffie-Hellman algorithm is commonly used as an automated method to securely exchange symmetric keys over a public network.
Asymmetric algorithms use two keys: one public and one private. The public key can be used for encryption and decryption of data and is sent to any requesting host. The private key can be used for encryption and decryption of data and is kept strictly for the sending host.
Certificates are not secret information and do not need to be encrypted in any way. The idea is not to hide anything but to ensure the authenticity and integrity of the information contained in the certificate.
Part I: Cisco CallManager Fundamentals
Introduction to Cisco Unified Communications and Cisco Unified CallManager
Cisco Unified CallManager Clustering and Deployment Options
Cisco Unified CallManager Installation and Upgrades
Part II: IPT Devices and Users
Cisco IP Phones and Other User Devices
Configuring Cisco Unified CallManager to Support IP Phones
Cisco IP Telephony Users
Cisco Bulk Administration Tool
Part III: IPT Network Integration and Route Plan
Cisco Catalyst Switches
Configuring Cisco Gateways and Trunks
Cisco Unified CallManager Route Plan Basics
Cisco Unified CallManager Advanced Route Plans
Configuring Hunt Groups and Call Coverage
Implementing Telephony Call Restrictions and Control
Implementing Multiple-Site Deployments
Part IV: VoIP Features
Configuring User Features, Part 1
Configuring User Features, Part 2
Configuring Cisco Unified CallManager Attendant Console
Configuring Cisco IP Manager Assistant
Part V: IPT Security
Securing the Windows Operating System
Securing Cisco Unified CallManager Administration
Preventing Toll Fraud
Hardening the IP Phone
Understanding Cryptographic Fundamentals
Understanding the Public Key Infrastructure
Understanding Cisco IP Telephony Authentication and Encryption Fundamentals
Configuring Cisco IP Telephony Authentication and Encryption
Part VI: IP Video
Introducing IP Video Telephony
Configuring Cisco VT Advantage
Part VII: IPT Management
Introducing Database Tools and Cisco Unified CallManager Serviceability
Configuring Alarms and Traces
Using Additional Management and Monitoring Tools
Part VIII: Appendix
Appendix A. Answers to Review Questions