This project implements an Enhanced version of the Simplified Data Encryption Standard (S-DES) algorithm. The Enhanced S-DES combines the original S-DES with additional security layers, including columnar transposition and shift rows operations, to create a more robust encryption scheme.
The main goals of this project are:
- To implement the basic S-DES algorithm
- To enhance its security by adding pre-processing steps
- To provide a flexible and user-friendly interface for encryption and decryption
To use this project, clone the repository and ensure you have a Python environment set up:
git clone https://github.com/D-Gaspa/enhanced_SDES.git
cd enhanced-sdesNo additional dependencies are required.
To run the Enhanced S-DES encryption system, execute the main.py script:
python main.pyThis will launch an interactive command-line interface with the following options:
- Encrypt a message
- Decrypt a message
- Change progress level
- Exit the program
When encrypting or decrypting, you'll be prompted to:
- Enter the message
- Provide or generate an S-DES key
- Provide or generate a transposition key
- Specify the number of transposition rounds
- Choose the progress level (0: None, 1: Normal, 2: Detailed)
Example session:
Welcome to the Enhanced S-DES Encryption System!
Enter 1 to encrypt, 2 to decrypt, 3 to change progress level, or 4 to exit: 3
Enter progress level (0: None, 1: Normal, 2: Detailed): 2
Progress level set to: DETAILED
Enter 1 to encrypt, 2 to decrypt, 3 to change progress level, or 4 to exit: 1
Enter the message to encrypt: Warning! We are compromised
Enter the 10-bit S-DES key (or press Enter to generate):
Generated S-DES key: 1010100110
Enter the transposition key (space/comma-separated or [list] format, or press Enter to generate):
Enter column size (2-26, or press Enter for default 3): 5
Generated transposition key: [4, 3, 2, 1, 5]
Enter the number of transposition rounds (or press Enter for default 2): 4
Plaintext: Warning! We are compromised
Initial Table:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| W | a | r | n | i |
+---------+---------+---------+---------+---------+
| n | g | ! | | W |
+---------+---------+---------+---------+---------+
| e | | a | r | e |
+---------+---------+---------+---------+---------+
| | c | o | m | p |
+---------+---------+---------+---------+---------+
| r | o | m | i | s |
+---------+---------+---------+---------+---------+
| e | d | | | |
+---------+---------+---------+---------+---------+
After round 1:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | i |
+---------+---------+---------+---------+---------+
| | r | ! | a | o |
+---------+---------+---------+---------+---------+
| m | | a | g | |
+---------+---------+---------+---------+---------+
| c | o | d | W | n |
+---------+---------+---------+---------+---------+
| e | | r | e | i |
+---------+---------+---------+---------+---------+
| W | e | p | s | |
+---------+---------+---------+---------+---------+
[... more rounds of transposition ...]
Columnar Transposition: "n rmoir!a m agnco Wie rdWepse "
Before Shift:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | o |
+---------+---------+---------+---------+---------+
| i | r | ! | a | |
+---------+---------+---------+---------+---------+
| m | | a | g | n |
+---------+---------+---------+---------+---------+
| c | o | | W | i |
+---------+---------+---------+---------+---------+
| e | | r | d | W |
+---------+---------+---------+---------+---------+
| e | p | s | e | |
+---------+---------+---------+---------+---------+
After Shift:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | o |
+---------+---------+---------+---------+---------+
| r | ! | a | | i |
+---------+---------+---------+---------+---------+
| a | g | n | m | |
+---------+---------+---------+---------+---------+
| W | i | c | o | |
+---------+---------+---------+---------+---------+
| W | e | | r | d |
+---------+---------+---------+---------+---------+
| e | p | s | e | |
+---------+---------+---------+---------+---------+
Shift Rows: "n rmor!a iagnm Wico We rdepse "
Converted to binary: 0110111000100000011100100110110101101111...(200 more characters)
Encrypting with S-DES:
Total blocks to process: 30
Key: 1010100110
Encrypting block 1/30
Input block: 01101110
Subkey generation:
Original key: 1010100110
After P10: 1100001110
After LS-1: 1000111100
Subkey 1: 10101100
After LS-2: 0011010011
Subkey 2: 11010011
Subkey 1: 10101100
Subkey 2: 11010011
After initial permutation: 11100011
Round input: L=1110, R=0011
Expanded R: 10010110
After XOR with subkey: 00111010
After S-boxes: 1000
After P4: 0001
Round output: 11110011
After first round: 11110011
After switch: 00111111
Round input: L=0011, R=1111
Expanded R: 11111111
After XOR with subkey: 00101100
After S-boxes: 0001
After P4: 0100
Round output: 01111111
After second round: 01111111
Final output: 10111111
Output block: 10111111
Current result: 10111111
[... more blocks encrypted ...]
Final encrypted result: 1011111110001011011101111010111101101010...(200 more characters)
Encrypted message (hex): BF8B77AF6A77C4D08BEAD044BFAF8B0AEA016A8B0A558B777A558EE7558B
Enter 1 to encrypt, 2 to decrypt, 3 to change progress level, or 4 to exit: 2
Use saved encryption info? (y/n): y
Enter the message to decrypt (hex): BF8B77AF6A77C4D08BEAD044BFAF8B0AEA016A8B0A558B777A558EE7558B
Ciphertext: BF8B77AF6A77C4D08BEAD044BFAF8B0AEA016A8B0A558B777A558EE7558B
Converted to binary: 1011111110001011011101111010111101101010...(200 more characters)
Decrypting with S-DES:
Total blocks to process: 30
Key: 1010100110
Decrypting block 1/30
Input block: 10111111
Subkey generation:
Original key: 1010100110
After P10: 1100001110
After LS-1: 1000111100
Subkey 1: 10101100
After LS-2: 0011010011
Subkey 2: 11010011
Subkey 1: 10101100
Subkey 2: 11010011
After initial permutation: 01111111
Round input: L=0111, R=1111
Expanded R: 11111111
After XOR with subkey: 00101100
After S-boxes: 0001
After P4: 0100
Round output: 00111111
After first round: 00111111
After switch: 11110011
Round input: L=1111, R=0011
Expanded R: 10010110
After XOR with subkey: 00111010
After S-boxes: 1000
After P4: 0001
Round output: 11100011
After second round: 11100011
Final output: 01101110
Output block: 01101110
Current result: 01101110
[... more blocks decrypted ...]
S-DES Decryption (binary): 0110111000100000011100100110110101101111...(200 more characters)
Converted to text: "n rmor!a iagnm Wico We rdepse "
Before Inverse Shift:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | o |
+---------+---------+---------+---------+---------+
| r | ! | a | | i |
+---------+---------+---------+---------+---------+
| a | g | n | m | |
+---------+---------+---------+---------+---------+
| W | i | c | o | |
+---------+---------+---------+---------+---------+
| W | e | | r | d |
+---------+---------+---------+---------+---------+
| e | p | s | e | |
+---------+---------+---------+---------+---------+
After Inverse Shift:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | o |
+---------+---------+---------+---------+---------+
| i | r | ! | a | |
+---------+---------+---------+---------+---------+
| m | | a | g | n |
+---------+---------+---------+---------+---------+
| c | o | | W | i |
+---------+---------+---------+---------+---------+
| e | | r | d | W |
+---------+---------+---------+---------+---------+
| e | p | s | e | |
+---------+---------+---------+---------+---------+
Inverse Shift Rows: "n rmoir!a m agnco Wie rdWepse "
Initial Table:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| n | | r | m | o |
+---------+---------+---------+---------+---------+
| i | r | ! | a | |
+---------+---------+---------+---------+---------+
| m | | a | g | n |
+---------+---------+---------+---------+---------+
| c | o | | W | i |
+---------+---------+---------+---------+---------+
| e | | r | d | W |
+---------+---------+---------+---------+---------+
| e | p | s | e | |
+---------+---------+---------+---------+---------+
[... more rounds of inverse transposition ...]
After round 4:
+---------+---------+---------+---------+---------+
| Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
+=========+=========+=========+=========+=========+
| W | a | r | n | i |
+---------+---------+---------+---------+---------+
| n | g | ! | | W |
+---------+---------+---------+---------+---------+
| e | | a | r | e |
+---------+---------+---------+---------+---------+
| | c | o | m | p |
+---------+---------+---------+---------+---------+
| r | o | m | i | s |
+---------+---------+---------+---------+---------+
| e | d | | | |
+---------+---------+---------+---------+---------+
Decrypted message: Warning! We are compromised
Enter 1 to encrypt, 2 to decrypt, 3 to change progress level, or 4 to exit: 4
Exiting the program. Goodbye!
This example demonstrates the detailed progress level (2), showing the step-by-step process of encryption, including the columnar transposition, shift rows operation, and S-DES encryption for the first block. The output for the remaining blocks is similar and has been omitted for brevity.
You can adjust the progress level to 1 (Normal) for less detailed output or 0 (None) for minimal output.
The Simplified Data Encryption Standard (S-DES) is a block cipher that operates on 8-bit blocks of plaintext using a 10-bit key. It involves:
- Initial Permutation (IP)
- Two rounds of a complex function fK, involving:
- Expansion/Permutation (E/P)
- XOR with a round key
- S-box substitutions
- 4-bit permutation (P4)
- Switch function (SW)
- Inverse Initial Permutation (IP^-1)
The columnar transposition technique rearranges the characters of the plaintext:
- Arrange the plaintext in rows of a matrix
- Read out the characters in a column order specified by the key
- Can and should be applied multiple times for increased security
The shift rows operation performs a cyclic shift on the rows of the input:
- First row: no shift
- Second row: shift one position left
- Third row: shift two positions left
- (Pattern continues for larger matrices)
Encryption:
- Apply Columnar Transposition (multiple rounds if specified)
- Perform Shift Rows operation
- Convert to binary
- Apply S-DES encryption
- Convert the result to hexadecimal
Decryption:
- Convert hexadecimal to binary
- Apply S-DES decryption
- Convert to text
- Perform inverse Shift Rows operation
- Apply inverse Columnar Transposition (multiple rounds if used in encryption)