[Deque]

This is an RC4 implementation in Java (also known as ARC4 or ARCFOUR).
This cipher generates pseudo random numbers based on a given key and performs an XOR operation on the message to encode it. It is used i.e. in SSL, WEP, HTTPS and SSH1.

Code:

package logic; public class RC4 { private char[] key; private int[] sbox; private static final int SBOX_LENGTH = 256; private static final int KEY_MIN_LENGTH = 5; public static void main(String[] args) { try { RC4 rc4 = new RC4("testkey"); char[] result = rc4.encrypt("hello there".toCharArray()); System.out.println("encrypted string:\n" + new String(result)); System.out.println("decrypted string:\n" + new String(rc4.decrypt(result))); } catch (InvalidKeyException e) { System.err.println(e.getMessage()); } } public RC4(String key) throws InvalidKeyException { setKey(key); } public RC4() { } public char[] decrypt(final char[] msg) { return encrypt(msg); } public char[] encrypt(final char[] msg) { sbox = initSBox(key); char[] code = new char[msg.length]; int i = 0; int j = 0; for (int n = 0; n < msg.length; n++) { i = (i + 1) % SBOX_LENGTH; j = (j + sbox[i]) % SBOX_LENGTH; swap(i, j, sbox); int rand = sbox[(sbox[i] + sbox[j]) % SBOX_LENGTH]; code[n] = (char) (rand ^ (int) msg[n]); } return code; } private int[] initSBox(char[] key) { int[] sbox = new int[SBOX_LENGTH]; int j = 0; for (int i = 0; i < SBOX_LENGTH; i++) { sbox[i] = i; } for (int i = 0; i < SBOX_LENGTH; i++) { j = (j + sbox[i] + key[i % key.length]) % SBOX_LENGTH; swap(i, j, sbox); } return sbox; } private void swap(int i, int j, int[] sbox) { int temp = sbox[i]; sbox[i] = sbox[j]; sbox[j] = temp; } public void setKey(String key) throws InvalidKeyException { if (!(key.length() >= KEY_MIN_LENGTH && key.length() < SBOX_LENGTH)) { throw new InvalidKeyException("Key length has to be between " + KEY_MIN_LENGTH + " and " + (SBOX_LENGTH - 1)); } this.key = key.toCharArray(); } } public class InvalidKeyException extends Exception { private static final long serialVersionUID = 1L; public InvalidKeyException(String message) { super(message); } }

[Deque]

This is an RC4 implementation in Java (also known as ARC4 or ARCFOUR).
This cipher generates pseudo random numbers based on a given key and performs an XOR operation on the message to encode it. It is used i.e. in SSL, WEP, HTTPS and SSH1.

Code:

package logic; public class RC4 { private char[] key; private int[] sbox; private static final int SBOX_LENGTH = 256; private static final int KEY_MIN_LENGTH = 5; public static void main(String[] args) { try { RC4 rc4 = new RC4("testkey"); char[] result = rc4.encrypt("hello there".toCharArray()); System.out.println("encrypted string:\n" + new String(result)); System.out.println("decrypted string:\n" + new String(rc4.decrypt(result))); } catch (InvalidKeyException e) { System.err.println(e.getMessage()); } } public RC4(String key) throws InvalidKeyException { setKey(key); } public RC4() { } public char[] decrypt(final char[] msg) { return encrypt(msg); } public char[] encrypt(final char[] msg) { sbox = initSBox(key); char[] code = new char[msg.length]; int i = 0; int j = 0; for (int n = 0; n < msg.length; n++) { i = (i + 1) % SBOX_LENGTH; j = (j + sbox[i]) % SBOX_LENGTH; swap(i, j, sbox); int rand = sbox[(sbox[i] + sbox[j]) % SBOX_LENGTH]; code[n] = (char) (rand ^ (int) msg[n]); } return code; } private int[] initSBox(char[] key) { int[] sbox = new int[SBOX_LENGTH]; int j = 0; for (int i = 0; i < SBOX_LENGTH; i++) { sbox[i] = i; } for (int i = 0; i < SBOX_LENGTH; i++) { j = (j + sbox[i] + key[i % key.length]) % SBOX_LENGTH; swap(i, j, sbox); } return sbox; } private void swap(int i, int j, int[] sbox) { int temp = sbox[i]; sbox[i] = sbox[j]; sbox[j] = temp; } public void setKey(String key) throws InvalidKeyException { if (!(key.length() >= KEY_MIN_LENGTH && key.length() < SBOX_LENGTH)) { throw new InvalidKeyException("Key length has to be between " + KEY_MIN_LENGTH + " and " + (SBOX_LENGTH - 1)); } this.key = key.toCharArray(); } } public class InvalidKeyException extends Exception { private static final long serialVersionUID = 1L; public InvalidKeyException(String message) { super(message); } }