Live Differential Attack
This tab demonstrates a real chosen-plaintext differential attack on the 4-round toy SPN cipher. We exploit a high-probability differential to recover the last round subkey.
Step 1: Choose Plaintext Difference
Step 2: Collect Ciphertext Pairs
0 pairs collected. Need ~500 for reliable recovery.
Step 3: Run Attack
Ready to analyze pairs.
Differential Trace Visualization
Watch how XOR differences propagate through the rounds of the cipher via S-box substitution and bit permutation.
Input difference
Input Difference
After S-box (Round 1)
After Permutation (Round 1)
S-box Analysis
The S-box is the only non-linear component of the cipher. Its differential properties determine the strength of the cipher against differential attacks.
S-box Substitution
Input (outer number) β Output (colored square)
Difference Distribution Table (DDT)
Rows: Input Difference β’ Columns: Output Difference β’ Colors show count (0-255 pairs)
S-box Strength Assessment
Historical Impact: Differential Cryptanalysis
Differential cryptanalysis was the cryptanalytic breakthrough of the late 20th century.
Eli Biham
Affiliation: Technion β Israel Institute of Technology
Co-inventor of differential cryptanalysis. Later designed Serpent cipher to resist his own technique.
Adi Shamir
Affiliation: Weizmann Institute of Science, Israel
Co-inventor of differential cryptanalysis. Legendary cryptographer and co-founder of RSA cryptosystem.
Timeline of Discovery
Original Paper:
Eli Biham and Adi Shamir. "Differential Cryptanalysis of DES-like Cryptosystems." Journal of Cryptology, vol. 4, no. 1, pp. 3β72, 1991.
Why Serpent Survived: Defense Against Differential Cryptanalysis
Eli Biham designed Serpent specifically to be immune to differential cryptanalysis and other attacks he had discovered.
Cipher Defense Comparison
| Property | DES (1977) | AES (2001) | Serpent (1998) |
|---|---|---|---|
| S-box Max DDT | 8 | 4 | 4 |
| Rounds | 16 | 10/12/14 | 32 |
| Differential Reach | 8 rounds | Beyond attack | Beyond attack |
| Design Philosophy | Proven secure (classified) | Resistant to known attacks | Hardened by attack inventor |
Portfolio Thread: A Cipher's Journey
This demo is part of a series exploring cipher design and cryptanalysis:
- biham-lens (you are here) β Attack-side: differential cryptanalysis
- iron-serpent β Defense-side: Serpent cipher designed to defeat differential attacks
- dead-sea-cipher β Historical failures: why ciphers break
- shamir-gate β The mind of Adi Shamir: RSA, differential cryptanalysis, secret sharing