## Difference Between DES and AES

**DES vs AES**

DES (Data Encryption Standard) is a rather old way of encrypting data so that the information could not be read by other people who might be intercepting traffic. DES is rather quite old and has since been replaced by a newer and better AES (Advanced Encryption Standard). The replacement was done due to the inherent weaknesses in DES that allowed the encryption to be broken using certain methods of attack. Common applications of AES, as of the moment, are still impervious to any type of cracking techniques, which makes it a good choice even for top secret information.

The inherent weakness in DES is caused by a couple of things that are already addressed in AES. The first is the very short 56 bit encryption key. The key is like a password that is necessary in order to decrypt the information. A 56 bit has a maximum of 256 combinations, which might seem like a lot but is rather easy for a computer to do a brute force attack on. AES can use a 128, 192, or 256 bit encryption key with 2^128, 2^192, 2^256 combinations respectively. The longer encryption keys make it much harder to break given that the system has no other weaknesses.

Another problem is the small block size used by DES, which is set at 64 bits. In comparison, AES uses a block size that is twice as long at 128 bits. In simple terms, the block size determines how much information you can send before you start having identical blocks, which leak information. People can intercept these blocks and use read the leaked information. For DES with 64 bits, the maximum amount of data that can be transferred with a single encryption key is 32GB; at this point another key needs to be used. With AES, it is at 256 exabytes or 256 billion gigabytes. It is probably safe to say that you can use a single AES encryption key for any application.

In terms of structure, DES uses the Feistel network which divides the block into two halves before going through the encryption steps. AES on the other hand, uses permutation-substitution, which involves a series of substitution and permutation steps to create the encrypted block.

Summary:

DES is really old while AES is relatively new

DES is breakable while AES is still unbreakable

DES uses a much smaller key size compared to AES

DES uses a smaller block size compared to AES

DES uses a balanced Feistel structure while AES uses substitution-permutation

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The article says

A 56 bit has a maximum of 256 combinations,

It should say

A 56 bit has a maximum of 2^56 (2 to the power 56) combinations,

Ram is correct – why hasn’t the error been corrected yet? It’s only been 473 days since he posted his comment, are the moderators/editors MIA here or what???

Very nice artical with required fundamentals

I was thinking something wasn’t right as I read that sentence over and over.

Nevertheless, good points.

very short and complete for a quick reference.

thanks