This experiment demonstrates how DES and Triple DES (3DES) operate on fixed-size 64-bit blocks. Follow the steps below in sequence.

Step 1: Review Part I Configuration

In Part I: Key Configuration, first observe the values shown in DES Configuration Overview:

• Current Message (must be 64 bits, shown as 8 groups of 8 bits)
• Key Part A (16 hexadecimal digits)
• Key Part B (16 hexadecimal digits)

Use the controls as needed:

• Change plaintext:
  • You can enter a custom 64-bit binary message (spaces are allowed between groups), or
  • Leave the prompt empty to generate a random 64-bit message.
  • Invalid message length/format is rejected with an inline error.
• Change Key A generates a random 16-hex-digit key for Part A.
• Change Key B generates a random 16-hex-digit key for Part B.

Step 2: Select Input Type in Part II

In Part II: Encryption/Decryption Operations, choose input format:

• ASCII (8 characters) for text like ABCDEFGH
• Hex (16 digits) for values like 0123456789ABCDEF

The placeholder and info hint update automatically based on the selected format.

Step 3: Enter Plaintext and Key

In Part II, provide:

• Plaintext in the selected format
• Key as exactly 16 hexadecimal digits

Validation behavior:

• Invalid plaintext/key shows inline error text next to the field and a red highlight.
• Valid input clears the error automatically.

Step 4: Run DES Encrypt/Decrypt

Use the DES buttons in Part II:

• DES Encrypt encrypts the plaintext with the provided key.
• DES Decrypt applies DES decryption with the provided key.
• The 64-bit result appears in Output.

If input is invalid, output is not generated until errors are fixed.

Step 5: Generate Triple DES Output

Click Show TDES Output in Part II to compute Triple DES using the current values:

• Input message from Part II plaintext field
• Key Part A from Part I
• Key Part B from Part I

Pipeline used:

• Encrypt with Key A
• Decrypt with Key B
• Encrypt with Key A

The final 64-bit value appears in TDES Output.

Step 6: Verify in Part III

In Part III: Answer Verification:

• Copy your computed 3DES value into Your Answer.
• Click Check Answer! to verify.

You will see a success or retry notification based on the match.

Step 7: Use Reveal Answer (Optional)

If needed, click Reveal Answer to view:

• The correct 3DES result for the current configuration
• A step-by-step explanation of the 3DES EDE process

Quick Practice Set

Use this known DES test vector in Part II:

• Input Type: Hex (16 digits)
• Plaintext: 0123456789ABCDEF
• Key: 133457799BBCDFF1
• Click DES Encrypt

Expected DES output corresponds to:

• 85E813540F0AB405 (shown in the simulation as grouped binary)