How the DES Algorithm Works

The DES algorithm was widely adopted after it became the standard for federal encryption in 1977. However, it was soon plagued by security concerns, and the advent increased computing power brought new evidence of its weaknesses. Eventually, DES was sidelined for the more sophisticated AES algorithm.

DES utilizes a 64 bit block size to split plaintext into chunks which are processed by the algorithm over 16 rounds. Each round is comprised of five different processes. The first step is a permutation which reorders data bits within an area to create mixed information. Then is the expansion, key mixing, and another permutation, which creates the encrypted.

Each round also includes an XOR operation, which uses the output of one round as input for the next. This XOR operation confuses the relationship between plaintext (plaintext) and ciphertext (ciphertext) which makes it harder for attackers to identify the secret code which will create the correct encrypted text.

The DES algorithm also uses S-boxes in order to further muddle up the data, making it more difficult for attackers to determine which bits are plaintext and which are ciphertext. In the final phase of each round, the expanded text is XORed with a 48-bit key that was generated from the previous round's key. This adds an additional layer of protection against brute-force attacks.

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