#include #include #include #include using namespace std; // ************************* // Date : 12 Apr 2019 // Developer : Melih Melik Sönmez // Description : Better Enxryption with Quadratic Equation (ax^2+bx+c = 0) // I had to write this code for my friend's son to understand why MATH is // important for developing. // Caution ! // For sololearn you had to input data // with SPACE like "2 4 7 TEXTTOENCRYPT" for input // sqrt() library function is used to find the square root of a number //ASCII Table 0-127 //ASCII table for characters 0-127. ASCII stands for American Standard for Code Information Interchange. //Many PC computers and many microcontrollers, including the BASIC Stamp, Propeller, and Ardunio, use //this code to assign a number to a keyboard function. Some numbers correspond to keyboard actions, such //as cursor up, cursor down, space, or delete. Other numbers correspond to printed characters and symbols. //The numbers 32–126 correspond to characters and symbols that can be displayed in the BASIC Stamp Debug //Terminal, the Parallax Serial Terminal for the Propeller, the Arduino Serial Monitor, and the Parallax //Serial LCDs. This is also a handy reference for sending text strings between wireless devices. Some //devices may have different responses to code numbers 0–31, and may also make custom use of characters //128–255 (not shown). // ************************* int main() { int i; char str[100]; // We want to increase security so we create speacial key for our equation (ax^2+bx+c=Ascii) float a, b, c; cout << "Enter 3 coefficients (a b c): "; cin >> a >> b >> c; // we want the word from user to encrypt cout << "Type a word to encrypt/decrypt:\t"; cin >> str; //we have the word in array of letters so for every letter in our array //we will use the equation with our keys (ax^2+bx+c=Ascii) int equation[sizeof(str)]; //For Loop to encrypt all letters in array with equation //we don't want a word longer than 100 chars //and also we want to end loop at the end of array for(i = 0; (i < 100 && str[i] != '\0'); i++){ //we write down the equation values of each letter in array for later use equation[i] = (a*str[i]*str[i])+(b*str[i])+c; // ASCII 0-127 explanation written up there please read to understand why % 127 // We changed the letters in array one by one str[i] = (equation[i] % 127); } // YAY we now print our array to see encrypted word cout << "\nEncrypted text: " << str << endl; //Ok we want our word back so we start to reverse encrption //we use same encrpted text as an input for(i = 0; (i < 100 && str[i] != '\0'); i++){ // we use Quadratic Equation Formula to find real value of our encrypted letters // and change the encrypted letters str[i] = (sqrt((b * b) - (-1)*(4 * a * (equation[i]-c) ))-b) / (2*a); } // YAY we get our word back with the power of MATH cout << "\nDecrypted text: " << str << endl; // See you later alligator ... return 0; }

Cipher Encryption with Quadratic Equation C++