El xifrat ROT13 (llegiu com a: gira 13 llocs) és un cas especial del xifrat Ceaser en què el canvi sempre és 13.
Així, cada lletra es desplaça 13 llocs per xifrar o desxifrar el missatge.
Heu de pensar que només és un altre xifrat de César què és diferent aquesta vegada? Doncs la diferència està en la seva implementació. L'enfocament és utilitzar dos diccionaris Python separats.
- El primer a cercar les diverses lletres segons el seu lloc en l'alfabet anglès per obtenir el nombre desplaçat
- El segon per obtenir les lletres que corresponen a aquests números desplaçats.
Implementació:
C++
java convertir cadena a int
// CPP program to implement> // ROT13 Caesar Cipher> #include> using> namespace> std;> // Map to lookup the index of alphabets> map <>char>,>int>>dict1;> // Map to lookup alphabets corresponding> // to the index after shift> map <>int>,>char>>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 { // 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 { // 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) << '
'; message = 'TRRXF SBE TRRXF'; shift = 13; cout << decrypt(message, shift) << '
'; return 0; } // This code is contributed by Sachin Bisht> |
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Java
diferència entre un gigabyte i un megabyte
// java program for the above approach> import> java.util.*;> public> class> Main {> >// Map to lookup the index of alphabets> >static> Map dict1 =>new> HashMap();> >// Map to lookup alphabets corresponding> >// to the index after shift> >static> Map dict2 =>new> HashMap();> >// Function to create map to lookup> >static> void> create_dict() {> >for>(>int> i =>1>; i <>27>; i++)> >dict1.put((>char>)(>64> + i), i);> >dict2.put(>0>,>'Z'>);> >for>(>int> i =>1>; i <>26>; i++)> >dict2.put(i, (>char>)(>64> + i));> >}> >// Function to encrypt the string> >// according to the shift provided> >static> String encrypt(String message,>int> shift) {> >String cipher =>''>;> >for>(>int> i =>0>; i // Checking for namespace if(message.charAt(i) != ' ') { // looks up the map and // adds the shift to the index int num = (dict1.get(message.charAt(i)) + shift) % 26; // looks up the second map for the // shifted alphabets and adds them cipher += dict2.get(num); } else { // adds space cipher += ' '; } } return cipher; } // Function to decrypt the string // according to the shift provided static String decrypt(String message, int shift) { String decipher = ''; for(int i = 0; i // checks for space if(message.charAt(i) != ' ') { // looks up the map and // subtracts the shift to the index int num = (dict1.get(message.charAt(i)) - shift + 26) % 26; // looks up the second map for the // shifted alphabets and adds them decipher += dict2.get(num); } else { // adds space decipher += ' '; } } return decipher; } // Driver code public static void main(String[] args) { create_dict(); String message = 'GEEKS FOR GEEKS'; int shift = 13; System.out.println(encrypt(message, shift)); message = 'TRRXF SBE TRRXF'; shift = 13; System.out.println(decrypt(message, shift)); } } // This code is contributed by prince> |
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Python 3
# 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()> |
canviar el cas de java
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C#
using> System;> using> System.Collections;> using> System.Collections.Generic;> using> System.Linq;> // C# program for the above approach> class> HelloWorld {> > >// Map to lookup the index of alphabets> >public> static> Dictionary<>char>,>int>>dict1 =>new> Dictionary<>char>,>int>>();> >// Map to lookup alphabets corresponding> >// to the index after shift> >public> static> Dictionary<>int>,>char>>dict2 =>new> Dictionary<>int>,>char>>();> >// Function to create map to lookup> >public> static> void> create_dict() {> >for>(>int> i = 1; i <27; i++)> >dict1.Add((>char>)(64 + i), i);> >dict2.Add(0,>'Z'>);> >for>(>int> i = 1; i <26; i++)> >dict2.Add(i, (>char>)(64 + i));> >}> >// Function to encrypt the string> >// according to the shift provided> >public> static> string> encrypt(>string> message,>int> shift) {> >string> cipher =>''>;> >for>(>int> i = 0; 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 public static string decrypt(string message, int shift) { string decipher = ''; for(int i = 0; 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; } static void Main() { create_dict(); string message = 'GEEKS FOR GEEKS'; int shift = 13; Console.WriteLine(encrypt(message, shift)); message = 'TRRXF SBE TRRXF'; shift = 13; Console.WriteLine(decrypt(message, shift)); } } // The code is contributed by Nidhi goel.> |
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algorisme per a la cerca binària
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Javascript
// Dictionary to lookup the index of alphabets> const 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> const 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> function> encrypt(message, shift) {> >let cipher =>''>;> >for> (let i = 0; i const letter = message[i]; // checking for space if (letter !== ' ') { // looks up the dictionary and // adds the shift to the index const 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 function decrypt(message, shift) { let decipher = ''; for (let i = 0; i const letter = message[i]; // checks for space if (letter !== ' ') { // looks up the dictionary and // subtracts the shift to the index const 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 function main() { // use 'toUpperCase()' function to convert any lowercase characters to uppercase let message = 'GEEKS FOR GEEKS'; let shift = 13; let result = encrypt(message.toUpperCase(), shift); console.log(result); message = 'TRRXF SBE TRRXF'; shift = 13; result = decrypt(message.toUpperCase(), shift); console.log(result); } main(); // This code is contributed by adityashatmfh> |
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variable de referència en java
>Sortida
TRRXF SBE TRRXF GEEKS FOR GEEKS>
Anàlisi: El xifrat ROT13 no és gaire segur, ja que només és un cas especial del xifrat César. El xifrat de Caesar es pot trencar mitjançant l'anàlisi de freqüència o simplement provant les 25 claus, mentre que el xifrat ROT13 es pot trencar només canviant les lletres 13 llocs. Per tant, no té cap utilitat pràctica.
Aplicació: ROT13 estava en ús al grup de notícies net.jokes a principis dels anys vuitanta.