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BSCIT

Network Security

Unit 4

Transport Level Security

Unit 4

#[fit] Transport Level Security

Topics

  1. Web Security Issues
  2. Secure Socket Layers (SSL)
  3. Transport Layer Security (TLS)
  4. HTTPS (HyperText Transfer Protocols)
  5. Secure Shell (SSH)

#[fit] 4.1 Web Security Issues

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[fit] http:// ⚔️ https://

[fit] 4.1.1 Web Security Threats

[fit] 4.1.2 Web Traffic Security Approaches

4.1.1 Web Security Threats

Two way of grouping Web Security Threats

> Nature of attack.

> Location of Attack.

Nature of attack.

1 Active Attack

2 Passive Attack

Location of Attack.

Client Server Architecture

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3 Locations for attack

  1. Client
  2. Server
  3. Network

In the context of web

  1. Web browser
  2. Web server
  3. Network traffic in between them

OSI Reference Model

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SSL History

  • SSL V1
  • SSL V2
  • SSL V3 / TLS V1.0
  • TLS V1.1
  • TLS V1.2 (Latest)
  • TLS V1.3 (Draft)

SSL Concepts

  • SSL Connection
  • SSL Session

SSL Architecture

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SSL Architecture

  • SSL Record Protocol
    1. The Change Cipher Spec Protocol
    • The Alert Protocol
    • The Handshake Protocol

SSL Record Protocol

  • Services
    • Message Integrity using MAC
    • Confidentiality using Symm. Enc.
  • Operation (6 Steps)

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Operation (6 Steps)

  1. App Data from Application Layer
  • Fragmentation
  • Compass
  • Add MAC
  • Encrypt
  • Add SSL Record Header

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SSL Record Header

  • Content Type ('text/html', 'audio/mp3', 'image/png')
  • Major Version
  • Minor Version
  • Compressed Length

SSL Record Protocol

    1. The Change Cipher Spec Protocol
    1. The Alert Protocol
    1. The Handshake Protocol

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1. The Change Cipher Spec Protocol

  • Simplest
  • Consists of single message
  • Single Byte with Value 1
  • Causes the pending state to be copied into the current state, which updates the cipher suite to be used on this connection.

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2. Alert Protocol

  • Convey SSL alerts to the peer-entity
  • 2 Bytes
  • First Byte - Denotes level of the message
    • Warning
    • Fatal
  • Alert code for specific alert

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3. Handshake Protocol

  • Size: Minimum 4 Bytes
  • Type (1B) indicates one of 10 SSL Handshake Protocol Message Types
  • Length (3B) indicates length of message in Bytes
  • Content (>=0B) indicates the parameters associated with the messages

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4 Phases of SSL Handshake

  1. Establish Security Capabilities
  2. Server Authentication and Key Exchange
  3. Client Authentication and Key Exchange
  4. Finish

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Transport Layer Security (TLS)