DES, or Data Encryption Standard, is a symmetric-key block cipher algorithm published in 1977. It encrypts data in 64-bit blocks using a 56-bit key. The algorithm performs 16 rounds of complex operations to transform plaintext into ciphertext. While historically significant, DES has been superseded by more secure algorithms like AES due to its vulnerability to brute-force attacks.
The DES encryption process begins with two crucial steps. First, the 64-bit plaintext block undergoes an initial permutation, where bits are rearranged according to a predefined table. This permutation doesn't add security but prepares the data for the main encryption rounds. Next, the permuted 64-bit block is divided into two equal halves: the left half L0 and the right half R0, each containing 32 bits. These halves will be processed through 16 rounds of the Feistel structure.