#include using namespace std; string prepare(string str, int len) { string newStr = ""; for (int i = 0; i < len;) { if (i + 1 < len) { if (str[i] == str[i + 1]) { newStr += char(str[i]), newStr += "x"; i++; } else { newStr += char(str[i]), newStr += char(str[i + 1]); i += 2; } } else { newStr += char(str[i]), newStr += "x"; i += 2; } } // cout << newStr << endl; return newStr; } void generateKeyTable(string key, int key_len, char keyT[5][5]) { int i, j, k; int dict[26] = {0}; for (i = 0; i < key_len; i++) { if (key[i] != 'j') dict[key[i] - 97] = 2; } dict['j' - 97] = 1; i = 0; j = 0; for (k = 0; k < key_len; k++) { if (dict[key[k] - 97] == 2) { dict[key[k] - 97] -= 1; keyT[i][j] = key[k]; j++; if (j == 5) { i++; j = 0; } } } for (k = 0; k < 26; k++) { if (dict[k] == 0) { keyT[i][j] = (char)(k + 97); j++; if (j == 5) { i++; j = 0; } } } // for (int i = 0; i < 5; i++) { // for (int j = 0; j < 5; j++) { // cout << keyT[i][j] << " "; // } // cout << endl; // } } void search(char keyT[5][5], char a, char b, int arr[]) { int i, j; if (a == 'j') a = 'i'; else if (b == 'j') b = 'i'; for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (keyT[i][j] == a) { arr[0] = i; arr[1] = j; } else if (keyT[i][j] == b) { arr[2] = i; arr[3] = j; } } } } int mod5(int a) { return (a % 5); } void encrypt(string str, int text_len, char keyT[5][5]) { int i, a[4]; for (i = 0; i < text_len; i += 2) { search(keyT, str[i], str[i + 1], a); if (a[0] == a[2]) { str[i] = keyT[a[0]][mod5(a[1] + 1)]; str[i + 1] = keyT[a[0]][mod5(a[3] + 1)]; } else if (a[1] == a[3]) { str[i] = keyT[mod5(a[0] + 1)][a[1]]; str[i + 1] = keyT[mod5(a[2] + 1)][a[1]]; } else { str[i] = keyT[a[0]][a[3]]; str[i + 1] = keyT[a[2]][a[1]]; } } cout << str << endl; } int main() { string text = "apple", key = "orange"; char keyT[5][5]; generateKeyTable(key, key.length(), keyT); string newText = prepare(text, text.length()); encrypt(newText, newText.size(), keyT); return 0; }

PlayFair.cpp