使用java语言实现移位密码加密过程

Program Cipher:=
{

//加密子进程

subroutine encryption(plaintext,key):=
{

(String)plaintext->(char[])plaintext->index(97)
/*ascII 编码 a 97 b 98

• “hello” -> {‘h’,‘e’,…} -> 102,120…
  *…x,y,z,a,b,…
  */

//加密算法
(index+key-26)%122 index+key>122,0<=key<=26,97<=inex<=122
(index+key)%122 97<=index+key<=122,0<=key<=26,97<=inex<=122

//ASCII码索引->字符串(加密后的信息)
index->String(ciphertext)
}

//解密子进程
subroutine decryption(ciphertext,key):=
{ //字符串->字符数组->ASCII码索引
(String)ciphertext->(char[])plaintext->index

//解密算法
//...,y,z,a,b,c,....
(index-key+26)%122   index-key<97, 0<=key<=26,97<=inex<=122	
(index-key)%122      97<=index-key<=122,0<=key<=26,97<=inex<=122

//ASCII码索引->字符串(解密后的信息)
index->String(plaintext)

}

main:main-program():=
{
//加密
encryption(plaintext,key)； //offset

//解密
decryption(ciphertext,key);

}

}