Each of the 16 rounds involves expansion, XOR with a subkey, substitution (via S-boxes), and permutation.
3DES was introduced to extend the life of DES by applying the algorithm three times to each data block, significantly increasing the effective key length to combat brute-force attacks. DES and 3DES
The inverse of the initial permutation to produce the final ciphertext. 2. Triple DES (3DES) Each of the 16 rounds involves expansion, XOR
Uses a Feistel network consisting of 16 rounds of processing. XOR with a subkey
Developed in the 1970s, DES was the global standard for decades before its 56-bit key became vulnerable to modern brute-force attacks.