ROT13 密码

ROT13 密码（读作“旋转 13 位”）是 Ceaser 密码的一种特殊情况，其中移位始终为 13。
因此，每个字母都移动了 13 个位置来加密或解密消息。

一世
你一定认为这只是另一个凯撒密码，那么这次有什么不同呢？那么区别在于它的实现。方法是使用两个单独的Python字典。

1. 第一个根据它们在英文字母表中的位置查找各种字母以获得移位的数字
2. 第二个获得与这些移位数字相对应的字母。

代码 ：

Python3

# Python program to implement
# ROT13 Caesar cipher
 
'''This script uses dictionaries instead of 'chr()' & 'ord()' function'''
 
# Dictionary to lookup the index of alphabets
dict1 = {'A' : 1, 'B' : 2, 'C' : 3, 'D' : 4, 'E' : 5,
        'F' : 6, 'G' : 7, 'H' : 8, 'I' : 9, 'J' : 10,
        'K' : 11, 'L' : 12, 'M' : 13, 'N' : 14, 'O' : 15,
        'P' : 16, 'Q' : 17, 'R' : 18, 'S' : 19, 'T' : 20,
        'U' : 21, 'V' : 22, 'W' : 23, 'X' : 24, 'Y' : 25, 'Z' : 26}
 
# Dictionary to lookup alphabets
# corresponding to the index after shift
dict2 = {0 : 'Z', 1 : 'A', 2 : 'B', 3 : 'C', 4 : 'D', 5 : 'E',
        6 : 'F', 7 : 'G', 8 : 'H', 9 : 'I', 10 : 'J',
        11 : 'K', 12 : 'L', 13 : 'M', 14 : 'N', 15 : 'O',
        16 : 'P', 17 : 'Q', 18 : 'R', 19 : 'S', 20 : 'T',
        21 : 'U', 22 : 'V', 23 : 'W', 24 : 'X', 25 : 'Y'}
 
# Function to encrypt the string
# according to the shift provided
def encrypt(message, shift):
    cipher = ''
    for letter in message:
        # checking for space
        if(letter != ' '):
            # looks up the dictionary and
            # adds the shift to the index
            num = ( dict1[letter] + shift ) % 26
            # looks up the second dictionary for
            # the shifted alphabets and adds them
            cipher += dict2[num]
        else:
            # adds space
            cipher += ' '
 
    return cipher
 
# Function to decrypt the string
# according to the shift provided
def decrypt(message, shift):
    decipher = ''
    for letter in message:
        # checks for space
        if(letter != ' '):
            # looks up the dictionary and
            # subtracts the shift to the index
            num = ( dict1[letter] - shift + 26) % 26
            # looks up the second dictionary for the
            # shifted alphabets and adds them
            decipher += dict2[num]
        else:
            # adds space
            decipher += ' '
 
    return decipher
 
# driver function to run the program
def main():
    # use 'upper()' function to convert any lowercase characters to uppercase
    message = "GEEKS FOR GEEKS"
    shift = 13
    result = encrypt(message.upper(), shift)
    print (result)
 
    message = "TRRXF SBE TRRXF"
    shift = 13
    result = decrypt(message.upper(), shift)
    print (result)
 
# Executes the main function
if __name__ == '__main__':
    main()

C++

// CPP program to implement
// ROT13 Caesar Cipher
 
#include
using namespace std;
 
// Map to lookup the index of alphabets
map  dict1;
 
// Map to lookup alphabets corresponding
// to the index after shift
map  dict2;
 
// Function to create map to lookup
void create_dict()
{
    for(int i = 1; i < 27; i++)
        dict1[char(64 + i)] = i;
    
    dict2[0] = 'Z';
     
    for(int i = 1; i < 26; i++)
        dict2[i] = char(64 + i);
         
    return;
}
 
// Function to encrypt the string
// according to the shift provided
string encrypt(string message, int shift)
{
    string cipher = "";
    for(int i = 0; i < message.size(); i++)
    {
        // Checking for namespace
        if(message[i] != ' ')
        {
            // looks up the map and
            // adds the shift to the index
            int num = (dict1[message[i]] + shift) % 26;
             
            // looks up the second map for the
            // shifted alphabets and adds them
            cipher += dict2[num];
        }
        else
        {
            // adds space
            cipher += " ";
        }
    }
    return cipher;
}
 
// Function to decrypt the string
// according to the shift provided
string decrypt(string message, int shift)
{
    string decipher = "";
    for(int i = 0; i < message.size(); i++)
    {
        // checks for space
        if(message[i] != ' ')
        {
            // looks up the map and
            // subtracts the shift to the index
            int num = (dict1[message[i]] - shift + 26) % 26;
            // looks up the second map for the
            // shifted alphabets and adds them
            decipher += dict2[num];
        }
        else
        {
            // adds space
            decipher += " ";
        }
    }
    return decipher;
}
 
// Driver code
int main()
{
    create_dict();
     
    string message = "GEEKS FOR GEEKS";
    int shift = 13;
     
    cout << encrypt(message, shift) << "\n";
     
    message = "TRRXF SBE TRRXF";
    shift = 13;
     
    cout << decrypt(message, shift) << "\n";
     
    return 0;
}
// This code is contributed by Sachin Bisht

Output :
TRRXF SBE TRRXF
GEEKS FOR GEEKS