Encryption and Decryption of String according to given technique
Last Updated :
27 Dec, 2022
Given a string S, the task is to encrypt the string and decrypt the string again to the original form.
Encryption Technique: If L is the length of the string, then take two values, one the ceil of ?L (say b), and the other floor of ?L (say a), and make a two-dimensional matrix having rows = a, and columns = b.
If rows*columns < L, then increase the value of a or b, whichever is minimum. Fill the matrix with the characters of the original string sequentially. After obtaining the matrix, read the matrix column-wise and print the obtained string.
Decryption Technique: If L is the length of the encrypted string, then again find the two values a and b, where a is the ceil value of the ?L and b is the floor value of the ?L. Similarly create a 2D Matrix in which store the string column-wise and read the matrix row-wise to get the string in the original form.
Encryption Approach:
- Find the length L of the string.
- Find the ceil and floor values of ?Length and assign them to the variables.
- Check if the product of the two variables >= Length, if not then increments the variable having a lesser value by 1.
- Create a 2D matrix and fill the characters of the string row-wise.
- Read the matrix column-wise to get the encrypted string.
Decryption Approach:
- Find the length L of the string.
- Find the ceil and floor values of ?Length and assign them to the variables.
- Create a 2D matrix and fill the matrix by characters of string column-wise.
- Read the matrix row-wise to get the decrypted string.
Below is the implementation of the above approach:
C++
// C++ implementation for Custom
// Encryption and Decryption of String
#include <bits/stdc++.h>
using namespace std;
// Function to encrypt the string
string encryption(string s)
{
int l = s.length();
int b = ceil(sqrt(l));
int a = floor(sqrt(l));
string encrypted;
if (b * a < l) {
if (min(b, a) == b) {
b = b + 1;
}
else {
a = a + 1;
}
}
// Matrix to generate the
// Encrypted String
char arr[a][b];
memset(arr, ' ', sizeof(arr));
int k = 0;
// Fill the matrix row-wise
for (int j = 0; j < a; j++) {
for (int i = 0; i < b; i++) {
if (k < l){
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// encrypted string
for (int j = 0; j < b; j++) {
for (int i = 0; i < a; i++) {
encrypted = encrypted +
arr[i][j];
}
}
return encrypted;
}
// Function to decrypt the string
string decryption(string s){
int l = s.length();
int b = ceil(sqrt(l));
int a = floor(sqrt(l));
string decrypted;
// Matrix to generate the
// Encrypted String
char arr[a][b];
memset(arr, ' ', sizeof(arr));
int k = 0;
// Fill the matrix column-wise
for (int j = 0; j < b; j++) {
for (int i = 0; i < a; i++) {
if (k < l){
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// decrypted string
for (int j = 0; j < a; j++) {
for (int i = 0; i < b; i++) {
decrypted = decrypted +
arr[i][j];
}
}
return decrypted;
}
// Driver Code
int main()
{
string s = "Geeks For Geeks";
string encrypted;
string decrypted;
// Encryption of String
encrypted = encryption(s);
cout << encrypted << endl;
// Decryption of String
decrypted = decryption(encrypted);
cout << decrypted;
return 0;
}
// Java implementation for Custom
// Encryption and Decryption of String
class GFG
{
// Function to encrypt the String
static String encryption(char[] s)
{
int l = s.length;
int b = (int) Math.ceil(Math.sqrt(l));
int a = (int) Math.floor(Math.sqrt(l));
String encrypted = "";
if (b * a < l)
{
if (Math.min(b, a) == b)
{
b = b + 1;
}
else
{
a = a + 1;
}
}
// Matrix to generate the
// Encrypted String
char [][]arr = new char[a][b];
int k = 0;
// Fill the matrix row-wise
for (int j = 0; j < a; j++)
{
for (int i = 0; i < b; i++)
{
if (k < l)
{
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// encrypted String
for (int j = 0; j < b; j++)
{
for (int i = 0; i < a; i++)
{
encrypted = encrypted +
arr[i][j];
}
}
return encrypted;
}
// Function to decrypt the String
static String decryption(char []s)
{
int l = s.length;
int b = (int) Math.ceil(Math.sqrt(l));
int a = (int) Math.floor(Math.sqrt(l));
String decrypted="";
// Matrix to generate the
// Encrypted String
char [][]arr = new char[a][b];
int k = 0;
// Fill the matrix column-wise
for (int j = 0; j < b; j++)
{
for (int i = 0; i < a; i++)
{
if (k < l)
{
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// decrypted String
for (int j = 0; j < a; j++)
{
for (int i = 0; i < b; i++)
{
decrypted = decrypted +
arr[i][j];
}
}
return decrypted;
}
// Driver Code
public static void main(String[] args)
{
String s = "Geeks For Geeks";
String encrypted;
String decrypted;
// Encryption of String
encrypted = encryption(s.toCharArray());
System.out.print(encrypted +"\n");
// Decryption of String
decrypted = decryption(encrypted.toCharArray());
System.out.print(decrypted);
}
}
// This code is contributed by PrinciRaj1992
# Python3 implementation for Custom
# Encryption and Decryption of String
from math import ceil,floor,sqrt
# Function to encrypt the
def encryption(s):
l = len(s)
b = ceil(sqrt(l))
a = floor(sqrt(l))
encrypted=""
if (b * a < l):
if (min(b, a) == b):
b = b + 1
else:
a = a + 1
# Matrix to generate the
# Encrypted String
arr = [[' ' for i in range(a)] for j in range(b)]
k = 0
# Fill the matrix row-wise
for j in range(a):
for i in range(b):
if (k < l):
arr[j][i] = s[k]
k += 1
# Loop to generate
# encrypted
for j in range(b):
for i in range(a):
encrypted = encrypted + arr[i][j]
return encrypted
# Function to decrypt the
def decryption(s):
l = len(s)
b = ceil(sqrt(l))
a = floor(sqrt(l))
decrypted=""
# Matrix to generate the
# Encrypted String
arr = [[' ' for i in range(a)] for j in range(b)]
k = 0
# Fill the matrix column-wise
for j in range(b):
for i in range(a):
if (k < l):
arr[j][i] = s[k]
k += 1
# Loop to generate
# decrypted
for j in range(a):
for i in range(b):
decrypted = decrypted + arr[i][j]
return decrypted
# Driver Code
s = "Geeks For Geeks"
encrypted=""
decrypted=""
# Encryption of String
encrypted = encryption(s)
print(encrypted)
# Decryption of String
decrypted = decryption(encrypted)
print(decrypted)
# This code is contributed by mohit kumar 29
// C# implementation for Custom
// Encryption and Decryption of String
using System;
class GFG
{
// Function to encrypt the String
static String encryption(char[] s)
{
int l = s.Length;
int b = (int) Math.Ceiling(Math.Sqrt(l));
int a = (int) Math.Floor(Math.Sqrt(l));
String encrypted = "";
if (b * a < l)
{
if (Math.Min(b, a) == b)
{
b = b + 1;
}
else
{
a = a + 1;
}
}
// Matrix to generate the
// Encrypted String
char [,]arr = new char[a, b];
int k = 0;
// Fill the matrix row-wise
for (int j = 0; j < a; j++)
{
for (int i = 0; i < b; i++)
{
if (k < l)
{
arr[j, i] = s[k];
}
k++;
}
}
// Loop to generate
// encrypted String
for (int j = 0; j < b; j++)
{
for (int i = 0; i < a; i++)
{
encrypted = encrypted +
arr[i, j];
}
}
return encrypted;
}
// Function to decrypt the String
static String decryption(char []s)
{
int l = s.Length;
int b = (int) Math.Ceiling(Math.Sqrt(l));
int a = (int) Math.Floor(Math.Sqrt(l));
String decrypted="";
// Matrix to generate the
// Encrypted String
char [,]arr = new char[a, b];
int k = 0;
// Fill the matrix column-wise
for (int j = 0; j < b; j++)
{
for (int i = 0; i < a; i++)
{
if (k < l)
{
arr[j, i] = s[k];
}
k++;
}
}
// Loop to generate
// decrypted String
for (int j = 0; j < a; j++)
{
for (int i = 0; i < b; i++)
{
decrypted = decrypted +
arr[i, j];
}
}
return decrypted;
}
// Driver Code
public static void Main(String[] args)
{
String s = "Geeks For Geeks";
String encrypted;
String decrypted;
// Encryption of String
encrypted = encryption(s.ToCharArray());
Console.Write(encrypted +"\n");
// Decryption of String
decrypted = decryption(encrypted.ToCharArray());
Console.Write(decrypted);
}
}
// This code is contributed by PrinciRaj1992
<script>
// JavaScript implementation for Custom
// Encryption and Decryption of let
// Function to encrypt the let
function encryption(s) {
let l = s.length;
let b = Math.ceil(Math.sqrt(l));
let a = Math.floor(Math.sqrt(l));
let encrypted = '';
if (b * a < l) {
if (Math.min(b, a) == b) {
b = b + 1;
}
else {
a = a + 1;
}
}
// Matrix to generate the
// Encrypted let
let arr = new Array();
for (let i = 0; i < a; i++) {
let temp = [];
for (let j = 0; j < b; j++) {
temp.push([])
}
arr.push(temp)
}
for (let i = 0; i < a; i++) {
for (let j = 0; j < b; j++) {
arr[i][j] = " "
}
}
let k = 0;
// Fill the matrix row-wise
for (let j = 0; j < a; j++) {
for (let i = 0; i < b; i++) {
if (k < l) {
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// encrypted let
for (let j = 0; j < b; j++) {
for (let i = 0; i < a; i++) {
encrypted = encrypted +
arr[i][j];
}
}
return encrypted;
}
// Function to decrypt the let
function decryption(s) {
let l = s.length;
let b = Math.ceil(Math.sqrt(l));
let a = Math.floor(Math.sqrt(l));
let decrypted = '';
// Matrix to generate the
// Encrypted let
let arr = new Array();
for (let i = 0; i < a; i++) {
let temp = [];
for (let j = 0; j < b; j++) {
temp.push([])
}
arr.push(temp)
}
for (let i = 0; i < a; i++) {
for (let j = 0; j < b; j++) {
arr[i][j] = " "
}
}
let k = 0;
// Fill the matrix column-wise
for (let j = 0; j < b; j++) {
for (let i = 0; i < a; i++) {
if (k < l) {
arr[j][i] = s[k];
}
k++;
}
}
// Loop to generate
// decrypted let
for (let j = 0; j < a; j++) {
for (let i = 0; i < b; i++) {
decrypted = decrypted + arr[i][j];
}
}
return decrypted;
}
// Driver Code
let s = "Geeks For Geeks";
let encrypted;
let decrypted;
// Encryption of let
encrypted = encryption(s);
document.write(encrypted + "<br>");
// Decryption of let
decrypted = decryption(encrypted);
document.write(decrypted);
// This code is contributed by gfgking
</script>
Output: Gsree keFGskoe
Geeks For Geeks
Time Complexity: O(?n * ?n) ? O(n)
Auxiliary Space: O(n), where n is the length of the given string.
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