1. Introduction | 简介
Triple DES (3DES) is an extended version of the Data Encryption Standard (DES), designed to enhance security by applying the DES algorithm three times in succession. Although 3DES is more secure than standard DES, it has been largely replaced by stronger encryption standards like AES. However, it still provides a foundation for understanding symmetric-key encryption.
三重数据加密标准（3DES） 是数据加密标准（DES）的扩展版本，旨在通过连续应用三次 DES 算法来增强安全性。虽然 3DES 比标准 DES 更安全，但已逐渐被 AES 等更强的加密标准所取代。然而，它仍然为理解对称密钥加密提供了基础。
2. Key Generation | 密钥生成
The key generation process of 3DES is the same as that of SDES, but the calculation amount is increased. In SDES, only K1 and K2 need to be calculated. However, in 3DES, K11, K12, K21, K22, K31, K32 need to be calculated (where K11, K21, K31 are calculated as K1. K12, K22, and K32 are calculated the same as K2).
3DES的密钥生成的过程和SDES的一样，只是计算量增大。在SDES中，只需要计算K1和K2。但是在3DES中需要计算K11，K12，K21，K22，K31，K32（其中K11，K21，K31计算和K1的一样。而K12，K22，K32计算和K2一样）。
Permutation P10 (Given value)
置换 P10（给定值）
Permutation P8 (Given value)
置换 P8（给定值）
For example, given a key1= 1011011101, key2=0110101110, key3=1100011011. According to the calculation process in the previous article, we can obtain K11 = 1101 1111 , K12 = 1110 1001,K21 = 0110 1100,K22 = 1101 0110,K31 = 1110 0011,K32 = 0010 1111.
例如，给定key1= 1011011101, key2=0110101110, key3=1100011011。根据前文中的计算过程，我们可以得到K11 = 1101 1111, K12 = 1110 1001,K21 = 0110 1100,K22 = 1101 0110,K31 = 1110 0011,K32 = 0010 1111。
3. S-Boxes (Given values) | S-盒（给定值）
Similarly, the S-box of 3DES is the same as DES.
S-Box 用于 SDES 算法中的替换操作。SDES 具有两个 S-盒：S0 和 S1。
4. Initial and Final Permutation | 初始和最终排列
The plaintext undergoes an initial permutation when it enters the encryption function, IP. It undergoes a reverse final permutation at the end IP−1 .
明文在进入加密函数IP时进行初始排列。最终在IP−1的末端进行反向排列。
IP (给定值)
IP-1 (给定值)
The steps are:
