1. CompTIA Security+ Study Guide (SY0-501)
Chapter 8:
Cryptography

2. Chapter 8: Cryptography
Compare and contrast types of attacks
Compare and contrast basic concepts of cryptography
Explain cryptography algorithms and their basic characteristics
Given a scenario, install and configure wireless security settings
Given a scenario, implement public key infrastructure

3. An Overview of Cryptography
Cryptography is a field almost as old as humankind.
Parts of:
Understanding nonmathematical cryptography
Substitution ciphers
A type of coding or ciphering system that changes one character or symbol into another
Transposition ciphers (transportation code)
Involves transposing or scrambling the letters in a certain manner

4. Chapter 8: Cryptography
Steganography
The process of hiding a message in a medium such as a digital image, audio file, or other file
Hybrid systems
Best when two or more of these methods of nonmathematical cryptography are combined
Mathematical cryptography
Deals with using mathematical processes on characters or messages
Hashing
Refers to performing a calculation on a message and converting it into a numeric hash value

5. Working with Symmetric Algorithms
Symmetric algorithms require both ends of an encrypted message to have the same key and processing algorithms.
Some common standards that use symmetric algorithms are the following:
Data Encryption Standard (DES)
Triple-DES (3DES)
Advanced Encryption Standard (AES)
CAST
GOST

6. Working with Asymmetric Algorithms
Asymmetric algorithms use two keys to encrypt and decrypt data.
Public key
Private key

7. Chapter 8: Cryptography
Cryptographic algorithms
Are used to encode a message from its unencrypted or clear-text state into an encrypted message
Hashing
The process of converting a message, or data, into a numeric value
Secure Hash Algorithm (SHA)
Message Digest Algorithm (MD)
Rainbow tables and salt
Key stretching

8. Code-Breaking Techniques
Frequency analysis
Involves looking at blocks of an encrypted message to determine if any common patterns exist
Algorithm errors
A method or set of instructions used to perform a task or instruction
Brute-force attacks
Can be accomplished by applying every possible combination of characters that could be the key
Exploiting human error
One of the major causes of encryption vulnerabilities

9. Chapter 8: Cryptography
Cryptographic system
A cryptographic system is a system, method, or process that is used to provide encryption and decryption.
Confidentiality and strength
Integrity
Digital signatures
Authentication
Nonrepudiation

10. Origins of Encryption Standards
Early cryptography standards were primarily designed to secure communications for the government and military.
Government agencies play a role.
National Security Agency (NSA)
National Security Agency/Central Security Service
National Institute of Standards and Technology
National Institute of Standards and Technology (NIST)

11. Public-Key Infrastructure X.509/Public-Key Cryptography Standards
Public-Key Infrastructure X.509 (PKIX)
The working group formed by the IETF to develop standards and models for the PKI environment
Public-Key Cryptography Standards (PKCS)
A set of voluntary standards created by RSA and security leaders

12. Chapter 8: Cryptography
X.509
Defines the certificate formats and fields for public keys; also defines the procedures that should be used to distribute public keys
SSL and TLS
Secure Sockets Layer (SSL)
Used to establish a secure communication connection between two TCP-based machines
Certificate Management Protocol (CMP)
A messaging protocol used between PKI entities
Secure Multipurpose Internet Mail Extensions (S/MIME)
A standard used for encrypting

13. Chapter 8: Cryptography
Pretty Good Privacy (PGP)
A freeware e‑mail encryption system
Hypertext Transport Protocol over SSL (HTTPS)
Secure Hypertext Transport Protocol (S-HTTP)
IP Security (IPSec)

14. Chapter 8: Cryptography
Tunneling protocols
Adds a capability to the network
Common protocols used for tunneling
Point-to-Point Tunneling Protocol (PPTP)
Layer 2 Forwarding (L2F)
Tunneling Protocol (L2TP)
Federal Information Processing Standard (FIPS)
A set of guidelines for the United States federal government information systems

15. Public Key Infrastructure
Public Key Infrastructure (PKI) is intended to provide a means of providing security to messages and transactions on a grand scale.
PKI is a two-key, asymmetric system with four main components.
Certificate authority (CA)
Registration authority (RA
RSA (the encryption algorithm)
Digital certificates

16. Chapter 8: Cryptography
Certificate authority (CA)
An organization that is responsible for issuing, revoking, and distributing certificates
Registration authority (RA)
Can distribute keys, accept registrations for the CA, and validate identities
Local registration authority (LRA)
Can be used to identify or establish the identity of an individual for certificate issuance

17. Implementing Certificates
provide the primary method of identifying that a given user is valid
can be used to store authorization information
can verify or certify that a system is using the correct software and processes to communicate

18. Chapter 8: Cryptography
Certificate policies
Define what certificates do
Certificate practice statement (CPS)
A detailed statement the CA uses to issue certificates and implement its policies

19. Certificate Revocation
The process of revoking a certificate before it expires
Certificate revocation list (CRL)
Online Certificate Status Protocol (OCSP)
Repository
A database or database server where the certificates are stored

20. Trust Models Four main types of trust models are used with PKI.
Hierarchical
Bridge
Mesh
Hybrid

21. Trust Models Hierarchical trust model
Also known as a tree; a root CA at the top provides all the information
Nridge trust model
A peer-to-peer relationship exists between the root CAs
Mesh trust model
Expands the concepts of the bridge model by supporting multiple paths and multiple root CAs
Hybrid trust model
Can use the capabilities of any or all of the structures discussed in the previous sections