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Security Engineering

3-Des Cryptology Method

3-Des is one of the interesting cryptology methods that we used for long time. Normal DES (Data encryption standard) uses 56 bit cryptology but 3-des uses 3 times more than that (168 bit) as it name suggests.

Here is an easy way to explain 3-Des.

c = des(des(des(p, k1, encrypt), k2, decrypt), k3, encrypt)

p = plaintext

c = ciphertext

k1, k2, k3 = keys)

Basic algorithm works in a way of encryption > decryption > encryption.

AES (Advanced encryption system) is more modern than DES (or 3-Des) and developed by Vincent Rijmen and Joan Daemen. They had a good and paranoid example in front of them (DES) and they aimed to lose DES’s negative ways and add more security. AES is theoretically more secure than DES, but in 2005, a group of computer programmers found a way to hack a PDF document which was encrypted with AES with “Cache timing attack”. (‘Tromer E, Osvik D, Shamir A’, ‘2010’) Although attack has had happened on the local machine where the PDF file was located, it still shows that these encryption system is not 100% secure.

When we need to consider about distributed networks, answer to this question is getting bit more easier. The answer is “no” for the most of computer experts for distributed networks, for time being. Because the time and resources required for this kind of job is quite a lot. But it doesn’t mean it will stay as it is. Principle of distributed networks e.g. SETI is easy, use as many computer as possible to create one big processor to use one aim from all over the world. But I assume, changing security key set on target location or even limit password trials would stop or let them waste time on trying.



‘Tromer E, Osvik D, Shamir A’, ‘2010’, ‘Efficient Cache Attacks on AES and Countermeasures’  ‘Tel Aviv University’ [Online] available from viewed 23 June 2012

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