Chapter 2 Cryptography

Cryptography Chapter 2

• Cryptography is used extensively for secure communication.
• Public Key Infrastructure (PKI) manages public and private keys for secure communication.
• Different encryption and hashing algorithms are crucial for cryptography.
• SCOR 350-701 exam objectives covered include security concepts, cryptographic components, hashing, encryption, PKI, SSL, IPsec, NAT-T IPv4, pre-shared keys, and certificate-based authorization.
• "Do I Know This Already?" quiz helps determine content needing review.
• Cryptography's foundations and topics covered in the chapter are outlined in a table mapping.
• Self-assessment is key; if unsure about an answer, mark it wrong.

Sub-topics

• Introduction to Cryptography

  • Cryptography is the study of techniques used for encryption and secure communications.
  • Cryptographers study and analyze cryptography.
  • Techniques focus on preventing unauthorized access to private messages.
  • Cryptography covers various information security areas like data confidentiality, data integrity, authentication, and nonrepudiation.

• Symmetric Encryption

  • Uses the same key for encryption and decryption.
  • Common examples: Advanced Encryption Standard (AES), Triple Digital Encryption Standard (3DES), and Blowfish.

• Asymmetric Encryption

  • Uses a pair of public and private keys.
  • One key encrypts, and the other decrypts.
  • Common examples: RSA and Diffie-Hellman key exchange.

• Ciphers

  • A cipher is a set of rules or algorithm used for encryption/decryption.
  • Common methods include substitution, where one character is replaced by another, and transposition, which involves rearranging characters.
  • Polyalphabetic ciphers use multiple alphabets for more complicated encryption.

• One-Time Pads (OTP)

  • A key used only once for encryption; highly secure but impractical for large amounts of data due to key management.

• Block and Stream Ciphers

  • Block ciphers operate on blocks of data at a time.
  • Examples: AES, 3DES, Blowfish, DES, IDEA, Serpent, and Twofish.
  • Stream ciphers work on bits or bytes. Cipher text stream output is generated. A given ciphertext stream does not have to fit in a particular block size.

• Keys

  • Keys are used for encryption & decryption. The key length is a crucial factor influencing security.
  • Longer keys offer greater security.
  • Symmetrical keys are simpler to manage and use.

• Hashing

  • Hashing is used for data integrity verification.
  • Creates a fixed-size hash value from any input (file, piece of data).
  • MD5 (Message Digest 5) and SHA (Secure Hash Algorithm) are common hashing algorithms, SHA-3 is recommended for security-sensitive applications.
    • Common uses in software downloads to verify integrity.

• Public Key Infrastructure (PKI)

  • PKI is a set of identities, roles, policies, and actions to manage public and private keys.
  • Includes digital certificates from a certificate authority (CA).

• Digital Signatures

  • Digital signatures use a private key to verify the authenticity and integrity of a digitally signed message or file.
  • Uses a digital verification procedure through public keys.

• Certificate Authorities (CAs)

  • CAs generate and issue digital certificates.

• Key Management

  • Key management procedures include generating keys, exchanging keys, storing keys and destroying keys at end-of-life.

• Key Hierarchies & Topologies

  • Single Root CAs (trusted entities in small networks)
  • Hierarchical CAs (employ subordinate CAs and are helpful in large networks).
  • Single CA design and hierarchical CAs.

• SSL and TLS

  • Protocols for secure communication over a public network.
  • TLS (Transport Layer Security) is a common protocol used today to handle secure web connections.

• Next-Generation Encryption (NGE)

  • Emerging protocols addressing evolving security needs and quantum computing threats.

Review Questions

• Review questions are provided with answers in the text.