This repository provides examples of using cryptography in Java for encryption and decryption purposes. basic algorithm
- Java Development Kit (JDK) 17 or higher
- Git (optional, for cloning the repository)
package algorithm;
import java.util.*;
public class ENCRYPT01 {
public static void run() {
String encrypted = encrypt("example");
System.out.println("Encrypted message: " + encrypted);
String decrypted = decrypt(encrypted);
System.out.println("Decrypted message: " + decrypted);
}
public static String encrypt(String input) {
// BREAKING APART - CONVERT INTO CHAR
char[] layer1 = input.toCharArray();
List<Character> layer2 = new ArrayList<>();
// LAYER 1 ENCRYPT - ADD TO LIST
for (int i = layer1.length - 1; i >= 0; i--) {
layer2.add(layer1[i]);
}
// LAYER 2 ENCRYPT - CHECK LOWERCASE AND UPPERCASE
char[] alphabets = "abcdefghijklmnopqrstuvwxyz".toCharArray();
char[] upperAlphabets = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
List<Character> layer3 = new ArrayList<>();
for (char currentChar : layer2) {
boolean found = false;
// Check lowercase alphabet
for (int j = 0; j < alphabets.length - 1; j++) {
if (alphabets[j] == currentChar) {
layer3.add(alphabets[j + 1]);
found = true;
break;
}
}
// Check uppercase alphabet
if (!found) {
for (int j = 0; j < upperAlphabets.length - 1; j++) {
if (upperAlphabets[j] == currentChar) {
layer3.add(upperAlphabets[j + 1]);
break;
}
}
}
}
// LAYER 3 - REPLACE WITH INDEX FOR 2, REPLACE WITH UPPERCASE FOR 3
for (int i = 0; i < layer3.size(); i++) {
if (i % 2 == 0) {
layer3.set(i, Character.forDigit(i / 2, 10)); // Adjusted radix for digits
} else if (i % 3 == 0) {
layer3.set(i, Character.toUpperCase(layer3.get(i)));
}
}
// LAYER 4 - APPEND RESULT STRING
StringBuilder result = new StringBuilder();
for (char c : layer3) {
result.append(c);
}
return result.toString();
}
public static String decrypt(String input) {
// LAYER 4 - CONVERT STRING TO LIST OF CHARACTERS
List<Character> layer3 = new ArrayList<>();
for (char c : input.toCharArray()) {
layer3.add(c);
}
// LAYER 3 - REVERSE TRANSFORMATIONS
List<Character> originalChars = new ArrayList<>(layer3);
for (int i = 0; i < layer3.size(); i++) {
if (i % 2 == 0) {
// Convert digits back to their original characters
int originalIndex = Character.getNumericValue(layer3.get(i)) * 2;
layer3.set(i, originalChars.get(originalIndex));
}
}
// LAYER 2 - REVERSE ALPHABET SHIFT
char[] alphabets = "abcdefghijklmnopqrstuvwxyz".toCharArray();
char[] upperAlphabets = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
List<Character> layer2 = new ArrayList<>();
for (char currentChar : layer3) {
boolean found = false;
// Check lowercase alphabet
for (int j = 1; j < alphabets.length; j++) {
if (alphabets[j] == currentChar) {
layer2.add(alphabets[j - 1]);
found = true;
break;
}
}
// Check uppercase alphabet
if (!found) {
for (int j = 1; j < upperAlphabets.length; j++) {
if (upperAlphabets[j] == currentChar) {
layer2.add(upperAlphabets[j - 1]);
break;
}
}
}
}
// LAYER 1 - REVERSE THE LIST TO GET ORIGINAL ORDER
Collections.reverse(layer2);
// Convert list back to string
StringBuilder result = new StringBuilder();
for (char c : layer2) {
result.append(c);
}
return result.toString();
}
}Encrypted message: 0m1N2y3
Decrypted message: xMlpackage algorithm;
public class ENCRYPT02 {
public static void run() {
data("simple cryptography method being developed");
}
public static void data(String encrypt){
char[] x = encrypt.toCharArray();
StringBuilder result = new StringBuilder();
for(char a : x){
a+=5;
result.append(a);
System.out.print(a);
}
System.out.println();
decrypt(String.valueOf(result));
}
public static void decrypt(String decrypt){
char[] brake = decrypt.toCharArray();
for(char x : brake){
x-=5;
System.out.print(x);
}
}
} encryption : xnruqj%hw~uytlwfum~%rjymti%gjnsl%ij{jqtuji
decryption : simple cryptography method being developedpackage algorithm;
public class ENCRYPT03 {
private static final String vocal = "AEIOUaeiou";
private static final char replacement = '#';
private static final char replacement2 = '&';
private static final char replacement3 = '*';
private static int shift = 0;
public static void run() {
String encryptedMessage = data("CAN YOU understand THESE???");
System.out.println("Encrypted: " + encryptedMessage);
String decryptedMessage = decrypt(encryptedMessage);
System.out.println("Decrypted: " + decryptedMessage);
}
public static String data(String encrypt) {
StringBuilder result = new StringBuilder();
for (char x : encrypt.toCharArray()) {
if (vocal.indexOf(x) != -1) {
if (shift > 3) {
result.append(replacement2);
} else {
result.append(replacement);
}
shift++;
} else {
result.append(x);
}
}
result.reverse();
return result.toString();
}
public static String decrypt(String encrypted) {
StringBuilder result = new StringBuilder(encrypted);
result.reverse(); // Reverse the reversal done in encryption
StringBuilder decrypted = new StringBuilder();
for (int i = 0; i < result.length(); i++) {
char currentChar = result.charAt(i);
if (currentChar == replacement || currentChar == replacement2 || currentChar == replacement3) {
if (shift > 3) {
decrypted.append(vocal.charAt(1)); // Replace with a specific vowel, adjust as needed
} else {
decrypted.append(vocal.charAt(0)); // Replace with a specific vowel, adjust as needed
}
shift++;
} else {
decrypted.append(currentChar);
}
}
return decrypted.toString();
}
}Encrypted: ???&S&HT dn&tsr&dn# ##Y N#C
Decrypted: CEN YEE EndErstEnd THESE???