How does the DES algorithm work?

Question

I am in doubt about how the Data Encryption Standard works, someone could explain in a didactic way?

Answer 1

What is the des?

The DES (Data Encryptation Standart) (or in English, information encryption standard) is a method of obtaining an asymmetric key for a virtual information, but today is already obsolete, advanced encryption systems no longer use this algorithm.

The algorithm was controversial and used a small-sized asymmetric key, DES gave inspiration for creating other, more secure algorithms, such as the Triple.

Taken from Wikipedia:

DES is a block cipher type, i.e., an algorithm that takes a String of fixed size of a plain text and transforms it, through a series of complicated operations, into a ciphertext of the same size. In the case of DES, the block size is 64 bits. DES also uses a key to customize/encrypt the transformation, so that decryption would only be theoretically possible by those who know the particular key used to encrypt (key). The key consists nominally of 64 bits, but only 56 of them are actually used by the algorithm. The remaining eight bits are used to check parity and are then discarded, so the effective key size is 56 bits, and so the key size is quoted.

Limited encryption

In summary, it is the oldest and "secure" algorithm used to encrypt fixed-size texts using a fixed-size key.

Its algorithm consists of 16 stages, the so-called "Rounds", and there are the initial and final permutations, called IP and FP, being IP undo what FP did, and vice versa.

These permutations make no significance to encryption itself, it was only used to facilitate the process of decoding and encoding information.

There’s no point in investing

The explanation of the algorithm is large and advanced, and requires a little time and willingness to understand its functioning, but in itself, it is not worth it. It pays a lot more to study new algorithms that are "safe" today.

But if you want to venture, here is the best explanation found.

In short, it is not recommended to use this algorithm in any of the situations this algorithm. There are better, faster and mostly safer than the same.