算法流程

1.将要处理的二进制串进行IP置换



2.将密钥进行PC1置换(64位转为56位),



3.进行16轮操作,对于第i轮操作:



1)将上一次得到的PC1密钥(级除去第一次外,其他的都经过移位处理)的结果左右部分(各28位)分别循环左移1位或2位,然后将移位后的密钥进行PC2[i]置换.



2)将处理串均等分为左右两串Li,Ri(各32位),然后将右串Ri通过E盒拓展为新的右串R (48位),R 与上一步得到的PC2[i]子密钥进行异或操作,结果通过S盒输出(48为转为32位),然后通过P盒直接置换,再与Li异或.



3)将Ri赋给作出Li,R 赋值给Ri.



4)合并处理串StrText=Li+Ri.



4.将最新的处理串进行IP_1置换,置换结果即为所求的加密串或解密串



加密解密的区别



在每轮操作中,加密使用的PC2密钥顺序为0~15,解密使用的PC2密钥顺序为15~0. -Algorithm flow

A binary string to be processed is substituted for IP



2 key the PC1 replacement (64 into 56)



16 operation, the operation for the i-th round:



1) about the results of the last PC1 key (remove the first time, the others have been shifting processing) (28) rotate left one or two, and then will shift key PC2 [i] replacement.



2) is divided into the equal treatment string around two bunches of Li, Ri (32), and then expand the right string Ri E box (48-bit), the right string R　R​ ​　 and the previous step PC2 i] subkey XOR operation result is output via the S-box (48 to 32 conversion), and then directly through the P box replacement and XOR with Li.



3) the Ri to make Li, R　is assigned to Ri.



4) merger deal with string StrText Ri = Li+.



4. Latest processing string IP_1 replacement, replacement results shall request string encryption or decryption string



Encryption and decryption of difference



In each round of operations, PC2 key e