Network security

Network security

• 1.
  Network Security Chapter 8
• 2.
  Cryptography • Introduction toCryptography • Substitution Ciphers • Transposition Ciphers • One-Time Pads • Two Fundamental Cryptographic Principles
• 3.
  Need for Security Somepeople who cause security problems and why.
• 4.
  An Introduction toCryptography The encryption model (for a symmetric-key cipher).
• 5.
  Transposition Ciphers A transpositioncipher.
• 6.
  One-Time Pads The useof a one-time pad for encryption and the possibility of getting any possible plaintext from the ciphertext by the use of some other pad.
• 7.
  Quantum Cryptography An exampleof quantum cryptography.
• 8.
  Symmetric-Key Algorithms • DES– The Data Encryption Standard • AES – The Advanced Encryption Standard • Cipher Modes • Other Ciphers • Cryptanalysis
• 9.
  Product Ciphers Basic elementsof product ciphers. (a) P-box. (b) S-box. (c) Product.
• 10.
  Data Encryption Standard Thedata encryption standard. (a) General outline. (b) Detail of one iteration. The circled + means exclusive OR.
• 11.
  Triple DES (a) Tripleencryption using DES. (b) Decryption.
• 12.
  AES – TheAdvanced Encryption Standard Rules for AES proposals 1. The algorithm must be a symmetric block cipher. 2. The full design must be public. 3. Key lengths of 128, 192, and 256 bits supported. 4. Both software and hardware implementations required 5. The algorithm must be public or licensed on nondiscriminatory terms.
• 13.
  AES (2) An outlineof Rijndael.
• 14.
  AES (3) Creating ofthe state and rk arrays.
• 15.
  Electronic Code BookMode The plaintext of a file encrypted as 16 DES blocks.
• 16.
  Cipher Block ChainingMode Cipher block chaining. (a) Encryption. (b) Decryption.
• 17.
  Cipher Feedback Mode (a)Encryption. (c) Decryption.
• 18.
  Stream Cipher Mode Astream cipher. (a) Encryption. (b) Decryption.
• 19.
  Counter Mode Encryption usingcounter mode.
• 20.
  Cryptanalysis Some common symmetric-keycryptographic algorithms.
• 21.
  Public-Key Algorithms • RSA •Other Public-Key Algorithms
• 22.
  RSA An example ofthe RSA algorithm.
• 23.
  Digital Signatures • Symmetric-KeySignatures • Public-Key Signatures • Message Digests • The Birthday Attack
• 24.
  Symmetric-Key Signatures Digital signatureswith Big Brother.
• 25.
  Public-Key Signatures Digital signaturesusing public-key cryptography.
• 26.
  Message Digests Digital signaturesusing message digests.
• 27.
  SHA-1 Use of SHA-1and RSA for signing nonsecret messages.
• 28.
  SHA-1 (2) (a) Amessage padded out to a multiple of 512 bits. (b) The output variables. (c) The word array.
• 29.
  Management of PublicKeys • Certificates • X.509 • Public Key Infrastructures
• 30.
  Problems with Public-KeyEncryption A way for Trudy to subvert public-key encryption.
• 31.
  Certificates A possible certificateand its signed hash.
• 32.
  X.509 The basic fieldsof an X.509 certificate.
• 33.
  Public-Key Infrastructures (a) Ahierarchical PKI. (b) A chain of certificates.
• 34.
  Communication Security • IPsec •Firewalls • Virtual Private Networks • Wireless Security
• 35.
  IPsec The IPsec authenticationheader in transport mode for IPv4.
• 36.
  IPsec (2) (a) ESPin transport mode. (b) ESP in tunnel mode.
• 37.
  Firewalls A firewall consistingof two packet filters and an application gateway.
• 38.
  Virtual Private Networks (a)A leased-line private network. (b) A virtual private network.
• 39.
  802.11 Security Packet encryptionusing WEP.
• 40.
  Authentication Protocols • AuthenticationBased on a Shared Secret Key • Establishing a Shared Key: Diffie-Hellman • Authentication Using a Key Distribution Center • Authentication Using Kerberos • Authentication Using Public-Key Cryptography
• 41.
  Authentication Based ona Shared Secret Key Two-way authentication using a challenge-response protocol.
• 42.
  Authentication Based ona Shared Secret Key (2) A shortened two-way authentication protocol.
• 43.
  Authentication Based ona Shared Secret Key (3) The reflection attack.
• 44.
  Authentication Based ona Shared Secret Key (4) A reflection attack on the protocol of Fig. 8-32.
• 45.
  Authentication Based ona Shared Secret Key (5) Authentication using HMACs.
• 46.
  Establishing a SharedKey: The Diffie-Hellman Key Exchange The Diffie-Hellman key exchange.
• 47.
  Establishing a SharedKey: The Diffie-Hellman Key Exchange The bucket brigade or man-in-the-middle attack.
• 48.
  Authentication Using aKey Distribution Center A first attempt at an authentication protocol using a KDC.
• 49.
  Authentication Using aKey Distribution Center (2) The Needham-Schroeder authentication protocol.
• 50.
  Authentication Using aKey Distribution Center (3) The Otway-Rees authentication protocol (slightly simplified).
• 51.
  Authentication Using Kerberos Theoperation of Kerberos V4.
• 52.
  Authentication Using Public-KeyCryptography Mutual authentication using public-key cryptography.
• 53.
  E-Mail Security • PGP– Pretty Good Privacy • PEM – Privacy Enhanced Mail • S/MIME
• 54.
  PGP – PrettyGood Privacy PGP in operation for sending a message.
• 55.
  PGP – PrettyGood Privacy (2) A PGP message.
• 56.
  Web Security • Threats •Secure Naming • SSL – The Secure Sockets Layer • Mobile Code Security
• 57.
  Secure Naming (a) Normalsituation. (b) An attack based on breaking into DNS and modifying Bob's record.
• 58.
  Secure Naming (2) HowTrudy spoofs Alice's ISP.
• 59.
  Secure DNS An exampleRRSet for bob.com. The KEY record is Bob's public key. The SIG record is the top-level com server's signed has of the A and KEY records to verify their authenticity.
• 60.
  Self-Certifying Names A self-certifyingURL containing a hash of server's name and public key.
• 61.
  SSL—The Secure SocketsLayer Layers (and protocols) for a home user browsing with SSL.
• 62.
  SSL (2) A simplifiedversion of the SSL connection establishment subprotocol.
• 63.
  SSL (3) Data transmissionusing SSL.
• 64.
  Java Applet Security Appletsinserted into a Java Virtual Machine interpreter inside the browser.
• 65.
  Social Issues • Privacy •Freedom of Speech • Copyright
• 66.
  Anonymous Remailers Users whowish anonymity chain requests through multiple anonymous remailers.
• 67.
  Freedom of Speech Possiblybanned material: 1. Material inappropriate for children or teenagers. 2. Hate aimed at various ethnic, religious, sexual, or other groups. 3. Information about democracy and democratic values. 4. Accounts of historical events contradicting the government's version. 5. Manuals for picking locks, building weapons, encrypting messages, etc.
• 68.
  Steganography (a) Three zebrasand a tree. (b) Three zebras, a tree, and the complete text of five plays by William Shakespeare.