1. Cracking the DES Encryption

2. Outline DES Encryption (in general). DES Vulnerabilities.
Cracking the DES (DESCHALL).
Using Condor Advantages.

3. DES Encryption
In general

4. History
In 1971, LUCIFER algorithm was developed. Cyphers block of 64 bits, using a 128-bit key
LUCIFER was refined by IBM researchers. The key was reduced to 56-bit: fits on a chip.
In 1977, the IBM project was adopted as the Data Encryption Standard (DES) by NSA.

5. Encryption Basics – Symmetric Key Encryption
Plaintext DEAD
Key BEEF
Ciphertext = 6042  =
Plaintext = DEAD
Ciphertext
Real Simple: Same key to encode and decode
Encoding and Decoding algorithms are symmetrical!

6. DES Algorithm Crypts 64 bits blocks of plain text.
Using a 56 bits key.
Expands the Symmetric Key Encryption
16 stages of processing Block Ciphers.
Initial & Final Permutations (IP, FP)
Using Feistel Function & Key Schedule

7. 48 bit subkey Generator Ki(48) = g(i,K(56)) (The key for each round is
Li-1
Ri-1 Li Ri
48 bit subkey
Generator
Ki(48) = g(i,K(56))
(The key for
each round is
deterministically
found from the
input 56 bit key).
Expansion Permutation
S-Box Substitution
P-Box Permutation 32 48
                        ,
                                                            
                                                                                          .

9. IP – Initial Permutation8 16 24 32 40 48 56
FP – Final Permutation 8 16 24 32 40 48 56

10. DES Advantages Strong encryption-Confusion and diffusion
Using a non linear function (S-Box)
Using bit permutation (P-Box)
Ideally suited for implementation in hardware (bit shifts, look-ups etc).
Suited for video & voice.

11. DES Vulnerabilities 
Are there any disadvantages?

12. Brute Force Attack
Basic attack for deciphering any kind of encrypted data.
Trying all possible options.
Takes a lot of time and resources.
Dedicated hardware is faster than software.

13. 56 bit Key - Advantage or Disadvantage?
256 possible keys =
72,057,594,037,927,936
Moore’s law compatible.
Even 20 years later(1997), it would take:
2,285 years to decipher!
With a 200 MHz Pentium system that can test approximately 1 million keys/second.

14. More Efficient Exploitations
Differential cryptanalysis
Linear cryptanalysis
Both require hundreds of Terabytes of cyphered & deciphered messages.
Still requires 2^43 iterations.
Dedicated machines.

15. DESCHALL Competition
Cracking the algorithm – it’s all about the money

16. The Challenge
RSA Security offered a 10,000$ prize in 1997, for the first who crack the DES.
A group of computer scientists involved thousands of volunteers deciphered it!
It took only 96 days! (against 2,285 years)
How did they manage to get a speedup of 8687 ???
How come the DES developers didn’t see it coming?

17. The Solution There was no internet when DES was introduced in 1977.
Even in 1997 the internet sounded bad.
Parallel Computing is the answer!
Simply using brute force.
With the help of up to 14k computers a day and a total of 78k unique computers.
By offering a 4,000$ prize to the computer owner who finds the right key.

18. DESCHALL Competition
How does it works?

19. Client Flowchart
Server Flowchart

21. Calculation Speed Average user speed is a sine form
Computers are more idle on weekends.

22. Growing popularity.
Parabolic growth of total calculated keys.
Only ¼ of all key options was needed to be calculate.

23. Can HTCondor Help?
Parallel computing using High Throughput Computing (HTC)

24. Condor Relevant Advantages
Sequential execution of a series of programs without human interaction.
Supports many different machines.
High throughput computing.
Open source and easy to setup.

26. Conclusions DES was outdated after DESCHALL.
Nowadays internet can help us achieve tremendous computing power with the growing amount of computers connected.
Longer keys are better bit key is common and believed to be hard to brute force (78 digits!)
Better encryption methods are in use today but they are also vulnerable!

27. Referances http://lasecwww.epfl.ch/memo/memo_des.shtml