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+--- Thread: [Java] RC4 implementation (/Thread-Java-RC4-implementation)
[Java] RC4 implementation - Deque - 05-16-2013
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);
}
}[Java] RC4 implementation - Deque - 05-16-2013
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);
}
}