Part 1: Basic CBC-MAC Implementation

STEP 1: Choose your learning approach

• Dataset Examples: Select from 4 pre-designed examples:
  • Example 1: Basic - Simple 2-block message for beginners
  • Example 2: Intermediate - 3-block message with step-by-step guidance
  • Example 3: Advanced - Complex multi-block scenario
  • Example 4: Complex - Challenging real-world example
• Random Mode: Click "Random Values" to generate random parameters for practice
• Navigation: Use "Previous Example" and "Next Example" to move between cases

STEP 2: Examine the CBC-MAC parameters

• Plaintext: View the provided binary message (automatically loaded from selected example)
• Key (k): Observe the cryptographic key (click "Next Key" for random key in free mode)
• IV Length (l): Note the initialization vector length (where l < plaintext length/2)
• IV: Study the initialization vector (click "Next IV" for random IV in free mode)

STEP 3: Test and understand the cryptographic function F_k

• Enter binary text of the required length in the "Your text" field
• Click "Apply Function" to see how F_k transforms your input using XOR/EQV operations
• Study the detailed calculation showing step-by-step bit operations
• Experiment: Click "Generate New Function" to try different function patterns
• Observe the function display showing the current F_k pattern

STEP 4: Follow the CBC-MAC algorithm step by step

• Understand the process: CBC-MAC XORs each plaintext block with the previous result
• Start with IV: The first block is XORed with the initialization vector
• Apply F_k function: Each XOR result is processed through the cryptographic function
• Continue iteratively: Use each F_k output as input for the next block's XOR operation
• Final result: The last F_k output is your CBC-MAC

STEP 5: Verify your calculation

• Enter your result in the "Final Output" field
• Check with dataset: Click "Check Answer!" to validate against the loaded example
• Alternative check: Click "Check (Original)" for direct algorithmic verification
• Learn from feedback: Review detailed explanations and corrections if needed
• Progress tracking: Successfully completed examples auto-advance to the next case

Part 2: Secure CBC-MAC Implementation

STEP 6: Learn about CBC-MAC security vulnerabilities

• Understand the risks: Basic CBC-MAC is vulnerable to length extension attacks
• Review attack scenarios: Variable-length messages can be manipulated by attackers
• Explore countermeasures: Different methods to make CBC-MAC secure

STEP 7: Select a security enhancement method

Choose from the dropdown menu to explore different security approaches:

• Compute and use your key: Manual key derivation and modification approach
• Prepend the message with its length: Length-prefixing to prevent extension attacks
• Two keys: Enhanced dual-key construction for increased security

STEP 8: Set up secure CBC-MAC parameters

• Plaintext: Click "Next Plaintext" to generate examples for secure analysis
• Key: Use "Next Key" to generate appropriate keys for your chosen security method
• IV Length and IV: Configure parameters following the same constraints as Part 1
• Observe differences: Note how security method affects parameter handling

STEP 9: Test the secure cryptographic function F_k

• Use enhanced interface: Same testing approach as Part 1 but with security modifications
• Apply secure function: Click "Apply Function" to see secure transformations
• Generate variations: Use "Generate New Function" for secure function patterns
• Study secure calculations: Observe how security measures affect the function output

STEP 10: Calculate secure CBC-MAC

• Follow enhanced algorithm: Apply your chosen security method to the CBC-MAC process
• Implement security measures: Use length prefixing, key derivation, or dual keys as selected
• Process systematically: Complete the calculation using the secure construction
• Validate each step: Ensure security measures are properly applied

STEP 11: Verify your secure implementation

• Enter final result: Input your calculated secure CBC-MAC in the output field
• Click "Check Secure CBC-MAC!": Validate your security-enhanced result
• Compare implementations: Understand differences between basic and secure approaches
• Learn from feedback: Review explanations of security measures and their effectiveness