import java.util.Arrays;
public class AES {
private static final int BITS = 16;
private static final int ROUNDS = 10;
private static final int NO_OF_WORDS_IN_KEY = 44;
private static final int KEY_LENGTH = 16;
private static final int BLOCK_LENGTH = 16;
final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
int[] RC = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36};
Word[] Rcon = new Word[ROUNDS];
private byte[] word = null;
static final int[] sBox = {
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};
static final int[] invSBox = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};
public AES() {
for (int i = 0 ; i < ROUNDS ; i++) {
Rcon[i] = new Word();
byte[] temp = new byte[4];
temp[0] = (byte) (RC[i] & 0xff);
temp[1] = 0;
temp[2] = 0;
temp[3] = 0;
Rcon[i].setWord(temp);
}
word = new byte[NO_OF_WORDS_IN_KEY];
}
/* Ref: http://www.samiam.org/galois.html */
/* Galois Addition*/
byte gadd(byte a, byte b) {
return (byte) ((a ^ b) & 0xff);
}
/* Galois Subtraction*/
byte gsub(byte a, byte b) {
return (byte) ((a ^ b) & 0xff);
}
/* Galois Multiplication*/
byte gmul(byte a, byte b) {
byte p = 0;
int counter;
byte high_bit_set;
byte byte0x80 = hexStringToByteArray("80")[0];
for (counter = 0 ; counter < 8 ; counter++) {
if((b & 0x01) == 1) {
//System.out.println("lower bit of b is set");
p = (byte)((p ^ a) & 0xff);
}
high_bit_set = (byte) (a & 0x80);
//printByte("high_bit_set", high_bit_set);
a <<= 1;
if (high_bit_set == byte0x80) {
//System.out.println("higher bit of a is set");
a = (byte)((a ^ 0x1b) & 0xff);
}
b = (byte)((b >> 1) & 0x7f);
//printByte("a", a);
//printByte("b", b);
//printByte("p", p);
}
return p;
}
byte gmul(byte a, int b) {
byte t = (byte)(b & 0xff);
return gmul(a, t);
}
/* Key Expansion */
private byte[] expandKey(byte[] key) throws Exception {
//System.out.println(key.length);
//System.out.println(bytesToHex(key));
if(key.length != KEY_LENGTH) {
throw new Exception("Key should be of length, 128 bits");
}
Word[] w = new Word[NO_OF_WORDS_IN_KEY];
Word temp;
for (int i = 0; i < 4; i++) {
w[i] = new Word(key[4*i], key[4*i+1], key[4*i+2], key[4*i+3]);
//System.out.println("w" + i + " = " + w[i]);
}
for (int i = 4; i < 44; i++) {
temp = w[i-1];
Word temp1 = new Word();
temp1.setWord(temp.getWord());
//System.out.println("w" + (i-1) + " = " + temp);
if (i % 4 == 0) {
temp1.rotWord();
//System.out.println("Rot=" + temp1);
temp1.subWord();
//System.out.println("Sub=" + temp1);
temp1 = Word.XORWords(temp1, Rcon[(i/4) - 1]);
//System.out.println("Rcon" + temp1);
}
w[i] = Word.XORWords(w[i-4], temp1);
//System.out.println("w" + i + " = " + w[i]);
}
return Word.wordsToBytes(w);
}
/* Substitute Bytes */
private byte[] subBytes(byte[] in) {
byte[] out = new byte[BITS];
for (int i = 0 ; i < BITS ; i++) {
byte a = in[i];
int row = (a >> 4) & 0x000F;
int col = a & 0x000F;
out[i] = (byte) sBox[row * BITS + col];
}
return out;
}
/* Inverse Substitute Bytes */
private byte[] inverseSubBytes(byte[] in) {
byte[] out = new byte[BITS];
for (int i = 0 ; i < BITS ; i++) {
byte a = in[i];
int row = (a >> 4) & 0x000F;
int col = a & 0x000F;
out[i] = (byte) invSBox[row * BITS + col];
}
return out;
}
/* Shift Rows */
private byte[] shiftRows(byte[] in) {
byte[] out = new byte[BITS];
byte[] temp = new byte[BITS];
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = in[4*i+j];
}
}
//System.out.println("temp: " + bytesToHex(temp));
for (int i = 0 ; i < BITS/4 ; i++) {
byte[] a = Arrays.copyOfRange(temp, (4 * i), (4 * i + 4));
byte[] b = leftShift(a, i);
in[4*i] = b[0];
in[4*i+1] = b[1];
in[4*i+2] = b[2];
in[4*i+3] = b[3];
}
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
out[4*j+i] = in[4*i+j];
}
}
return out;
}
private byte[] leftShift(byte[] in, int times) {
byte[] out = new byte[4];
out = Arrays.copyOfRange(in, 0, 4);
for (int i = 0 ; i < times ; i++) {
out[0] = in[1];
out[1] = in[2];
out[2] = in[3];
out[3] = in[0];
in = Arrays.copyOfRange(out, 0, 4);
}
return out;
}
/* Inverse Shift Rows */
private byte[] inverseShiftRows(byte[] in) {
byte[] out = new byte[BITS];
byte[] temp = new byte[BITS];
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = in[4*i+j];
}
}
for (int i = 0 ; i < BITS/4 ; i++) {
byte[] a = Arrays.copyOfRange(temp, (4 * i), (4 * i + 4));
byte[] b = rightShift(a, i);
in[4 * i] = b[0];
in[4 * i + 1] = b[1];
in[4 * i + 2] = b[2];
in[4 * i + 3] = b[3];
}
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
out[4*j+i] = in[4*i+j];
}
}
return out;
}
private byte[] rightShift(byte[] in, int times) {
byte[] out = new byte[4];
out = Arrays.copyOfRange(in, 0, 4);
for (int i = 0 ; i < times ; i++) {
out[0] = in[3];
out[1] = in[0];
out[2] = in[1];
out[3] = in[2];
in = Arrays.copyOfRange(out, 0, 4);
}
return out;
}
/* Mix Columns */
private byte[] mixColumns(byte[] in) {
byte[] out = new byte[BITS];
byte[] temp = new byte[BITS];
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = in[4*i+j];
}
}
in = temp;
for (int j = 0 ; j < BITS/4 ; j++) {
out[4*0+j] = (byte) ((gmul(in[4*0+j], 2) ^ gmul(in[4*1+j], 3) ^ in[4*2+j] ^ in[4*3+j]) & 0xff);
out[4*1+j] = (byte) ((in[4*0+j] ^ gmul(in[4*1+j], 2) ^ gmul(in[4*2+j], 3) ^ in[4*3+j]) & 0xff);
out[4*2+j] = (byte) ((in[4*0+j] ^ in[4*1+j] ^ gmul(in[4*2+j], 2) ^ gmul(in[4*3+j], 3)) & 0xff);
out[4*3+j] = (byte) ((gmul(in[4*0+j], 3) ^ in[4*1+j] ^ in[4*2+j] ^ gmul(in[4*3+j], 2)) & 0xff);
}
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = out[4*i+j];
}
}
out = temp;
return out;
}
/* Inverse Mix Columns */
private byte[] inverseMixColumns(byte[] in) {
byte[] out = new byte[BITS];
byte[] temp = new byte[BITS];
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = in[4*i+j];
}
}
in = temp;
for (int j = 0 ; j < BITS/4 ; j++) {
out[4*0+j] = (byte) ((gmul(in[4*0+j], 14) ^ gmul(in[4*1+j], 11) ^ gmul(in[4*2+j], 13) ^ gmul(in[4*3+j], 9)) & 0xff);
out[4*1+j] = (byte) ((gmul(in[4*0+j], 9) ^ gmul(in[4*1+j], 14) ^ gmul(in[4*2+j], 11) ^ gmul(in[4*3+j], 13)) & 0xff);
out[4*2+j] = (byte) ((gmul(in[4*0+j], 13) ^ gmul(in[4*1+j], 9) ^ gmul(in[4*2+j], 14) ^ gmul(in[4*3+j], 11)) & 0xff);
out[4*3+j] = (byte) ((gmul(in[4*0+j], 11) ^ gmul(in[4*1+j], 13) ^ gmul(in[4*2+j], 9) ^ gmul(in[4*3+j], 14)) & 0xff);
}
for (int i = 0 ; i < BITS/4 ; i++) {
for (int j = 0 ; j < BITS/4 ; j++) {
temp[4*j+i] = out[4*i+j];
}
}
out = temp;
return out;
}
private byte[] hexStringToByteArray(String string) {
int length = string.length();
int n = (int)Math.ceil((length + 1) / 2);
byte[] result = new byte[n];
for (int i = length - 1; i >= 0 ; i -= 2) {
if (i == 0) {
result[i / 2] = (byte) ((Character.digit('0', 16) << 4)
+ Character.digit(string.charAt(i), 16));
} else {
result[i / 2] = (byte) ((Character.digit(string.charAt(i - 1), 16) << 4)
+ Character.digit(string.charAt(i), 16));
}
}
return result;
}
/* http://stackoverflow.com/questions/9655181/convert-from-byte-array-to-hex-string-in-java */
public static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for ( int j = 0; j < bytes.length; j++ ) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
private void printBytes(byte[] input) {
for (int i = 0 ; i < input.length; i++) {
System.out.print(byteToBits(input[i]) + " ");
}
System.out.println();
}
private void printByte(String msg, byte input) {
byte[] temp = new byte[1];
temp[0] = input;
System.out.println(msg + ": " + bytesToHex(temp));
}
private String byteToBits(byte b) {
StringBuffer buffer = new StringBuffer();
for (int i = 0 ; i < 8 ; i++)
buffer.append((int)(b >> (8-(i+1)) & 0x0001));
return buffer.toString();
}
private byte[] getRoundKey(int round) {
byte[] out = new byte[KEY_LENGTH];
out = Arrays.copyOfRange(word, 16*round, 16*round+16);
return out;
}
public static byte[] XORBytes(byte[] in1, byte[] in2) {
byte[] out = new byte[BLOCK_LENGTH];
for (int i = 0 ; i < BLOCK_LENGTH ; i++) {
out[i] = (byte)((in1[i] ^ in2[i]) & 0xff);
}
return out;
}
public byte[] encrypt(byte[] plainText, byte[] key) throws Exception {
byte[] cipher = new byte[BLOCK_LENGTH];
this.word = expandKey(key);
byte[] roundKey = getRoundKey(0);
/* Round 0 */
cipher = XORBytes(plainText, roundKey);
//System.out.println("Round 0\n" + bytesToHex(cipher));
/* Rounds 1 to 9*/
for (int i = 1 ; i < 10 ; i++) {
//System.out.println("Round " + i);
cipher = subBytes(cipher);
//System.out.println("SubBytes: " + bytesToHex(cipher));
cipher = shiftRows(cipher);
//System.out.println("ShiftRows: " + bytesToHex(cipher));
cipher = mixColumns(cipher);
//System.out.println("MixColumns: " + bytesToHex(cipher));
roundKey = getRoundKey(i);
//System.out.println("RoundKey: " + bytesToHex(roundKey));
cipher = XORBytes(cipher, roundKey);
//System.out.println("CIPHER: " + bytesToHex(cipher));
}
/* Round 10*/
//System.out.println("Round 10");
cipher = subBytes(cipher);
//System.out.println("SubBytes: " + bytesToHex(cipher));
cipher = shiftRows(cipher);
//System.out.println("ShiftRows: " + bytesToHex(cipher));
roundKey = getRoundKey(10);
//System.out.println("RoundKey: " + bytesToHex(roundKey));
cipher = XORBytes(cipher, roundKey);
//System.out.println("CIPHER: " + bytesToHex(cipher));
return cipher;
}
public byte[] decrypt(byte[] cipher, byte[] key) throws Exception {
byte[] plainText = new byte[BLOCK_LENGTH];
this.word = expandKey(key);
byte[] roundKey = getRoundKey(10);
/* Round 0 */
plainText = XORBytes(cipher, roundKey);
/* Rounds 1 to 9*/
for (int i = 9 ; i > 0 ; i--) {
plainText = inverseShiftRows(plainText);
plainText = inverseSubBytes(plainText);
roundKey = getRoundKey(i);
plainText = XORBytes(plainText, roundKey);
plainText = inverseMixColumns(plainText);
}
/* Round 10*/
plainText = inverseShiftRows(plainText);
plainText = inverseSubBytes(plainText);
roundKey = getRoundKey(0);
plainText = XORBytes(plainText, roundKey);
return plainText;
}
public static void main(String[] args) throws Exception {
AES aes = new AES();
byte[] plainText = aes.hexStringToByteArray("0123456789abcdeffedcba9876543210");
System.out.println("PLAIN TEXT: " + bytesToHex(plainText));
byte[] key = aes.hexStringToByteArray("0f1571c947d9e8590cb7add6af7f6798");
System.out.println("KEY: " + bytesToHex(key));
byte[] cipher = aes.encrypt(plainText, key);
System.out.println("CIPHER TEXT: " + bytesToHex(cipher));
plainText = aes.decrypt(cipher, key);
System.out.println("DECRYPTED CIPHER TEXT: " + bytesToHex(plainText));
}
}
Word.java
public class Word {
private byte[] word = null;
public Word() {
word = new byte[4];
}
public Word(byte k0, byte k1, byte k2, byte k3) {
this();
word[0] = k0;
word[1] = k1;
word[2] = k2;
word[3] = k3;
}
public byte[] getWord() {
return word;
}
public void setWord(byte[] word) {
this.word = word;
}
public static byte[] wordToBytes(Word word) {
return word.getWord();
}
public static byte[] wordsToBytes(Word[] words) {
byte[] out = new byte[4 * words.length];
for (int i = 0 ; i < words.length ; i++) {
byte[] temp = words[i].getWord();
out[4*i] = temp[0];
out[4*i+1] = temp[1];
out[4*i+2] = temp[2];
out[4*i+3] = temp[3];
}
return out;
}
public void rotWord() {
byte[] temp = this.getWord();
byte[] newWord = new byte[4];
newWord[0] = temp[1];
newWord[1] = temp[2];
newWord[2] = temp[3];
newWord[3] = temp[0];
this.setWord(newWord);
}
public void subWord() {
byte[] in = this.getWord();
byte[] out = new byte[4];
for (int i = 0 ; i < 4 ; i++) {
byte a = in[i];
int row = (a >> 4) & 0x000F;
int col = a & 0x000F;
out[i] = (byte) AES.sBox[row * 16 + col];
}
for (int i = 0 ; i < 4 ; i++) {
this.word[i] = out[i];
}
}
public static Word XORWords(Word word1, Word word2) {
Word outWord = new Word();
byte[] in1 = word1.getWord();
byte[] in2 = word2.getWord();
byte[] out = new byte[4];
for (int i = 0 ; i < 4 ; i++) {
out[i] = (byte)((in1[i] ^ in2[i]) & 0xff);
}
outWord.setWord(out);
return outWord;
}
public String toString() {
return AES.bytesToHex(this.getWord());
}
}
OutputPLAIN TEXT: 0123456789ABCDEFFEDCBA9876543210
KEY: 0F1571C947D9E8590CB7ADD6AF7F6798
CIPHER TEXT: FF0B844A0853BF7C6934AB4364148FB9
DECRYPTED CIPHER TEXT: 0123456789ABCDEFFEDCBA9876543210
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