package javastory.cryptography;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.security.Security;
import javastory.tools.HexTool;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
/**
* Provides AES cryptographic rolling transformation.
*
* @author shoftee
*/
public class AesTransform {
private static final int IV_LENGTH = 16;
private static final int BLOCK_LENGTH = 1460;
private static final byte[] SHUFFLE_TABLE = { (byte) 0xEC, (byte) 0x3F, (byte) 0x77, (byte) 0xA4, (byte) 0x45, (byte) 0xD0, (byte) 0x71, (byte) 0xBF,
(byte) 0xB7, (byte) 0x98, (byte) 0x20, (byte) 0xFC, (byte) 0x4B, (byte) 0xE9, (byte) 0xB3, (byte) 0xE1,
(byte) 0x5C, (byte) 0x22, (byte) 0xF7, (byte) 0x0C, (byte) 0x44, (byte) 0x1B, (byte) 0x81, (byte) 0xBD,
(byte) 0x63, (byte) 0x8D, (byte) 0xD4, (byte) 0xC3, (byte) 0xF2, (byte) 0x10, (byte) 0x19, (byte) 0xE0,
(byte) 0xFB, (byte) 0xA1, (byte) 0x6E, (byte) 0x66, (byte) 0xEA, (byte) 0xAE, (byte) 0xD6, (byte) 0xCE,
(byte) 0x06, (byte) 0x18, (byte) 0x4E, (byte) 0xEB, (byte) 0x78, (byte) 0x95, (byte) 0xDB, (byte) 0xBA,
(byte) 0xB6, (byte) 0x42, (byte) 0x7A, (byte) 0x2A, (byte) 0x83, (byte) 0x0B, (byte) 0x54, (byte) 0x67,
(byte) 0x6D, (byte) 0xE8, (byte) 0x65, (byte) 0xE7, (byte) 0x2F, (byte) 0x07, (byte) 0xF3, (byte) 0xAA,
(byte) 0x27, (byte) 0x7B, (byte) 0x85, (byte) 0xB0, (byte) 0x26, (byte) 0xFD, (byte) 0x8B, (byte) 0xA9,
(byte) 0xFA, (byte) 0xBE, (byte) 0xA8, (byte) 0xD7, (byte) 0xCB, (byte) 0xCC, (byte) 0x92, (byte) 0xDA,
(byte) 0xF9, (byte) 0x93, (byte) 0x60, (byte) 0x2D, (byte) 0xDD, (byte) 0xD2, (byte) 0xA2, (byte) 0x9B,
(byte) 0x39, (byte) 0x5F, (byte) 0x82, (byte) 0x21, (byte) 0x4C, (byte) 0x69, (byte) 0xF8, (byte) 0x31,
(byte) 0x87, (byte) 0xEE, (byte) 0x8E, (byte) 0xAD, (byte) 0x8C, (byte) 0x6A, (byte) 0xBC, (byte) 0xB5,
(byte) 0x6B, (byte) 0x59, (byte) 0x13, (byte) 0xF1, (byte) 0x04, (byte) 0x00, (byte) 0xF6, (byte) 0x5A,
(byte) 0x35, (byte) 0x79, (byte) 0x48, (byte) 0x8F, (byte) 0x15, (byte) 0xCD, (byte) 0x97, (byte) 0x57,
(byte) 0x12, (byte) 0x3E, (byte) 0x37, (byte) 0xFF, (byte) 0x9D, (byte) 0x4F, (byte) 0x51, (byte) 0xF5,
(byte) 0xA3, (byte) 0x70, (byte) 0xBB, (byte) 0x14, (byte) 0x75, (byte) 0xC2, (byte) 0xB8, (byte) 0x72,
(byte) 0xC0, (byte) 0xED, (byte) 0x7D, (byte) 0x68, (byte) 0xC9, (byte) 0x2E, (byte) 0x0D, (byte) 0x62,
(byte) 0x46, (byte) 0x17, (byte) 0x11, (byte) 0x4D, (byte) 0x6C, (byte) 0xC4, (byte) 0x7E, (byte) 0x53,
(byte) 0xC1, (byte) 0x25, (byte) 0xC7, (byte) 0x9A, (byte) 0x1C, (byte) 0x88, (byte) 0x58, (byte) 0x2C,
(byte) 0x89, (byte) 0xDC, (byte) 0x02, (byte) 0x64, (byte) 0x40, (byte) 0x01, (byte) 0x5D, (byte) 0x38,
(byte) 0xA5, (byte) 0xE2, (byte) 0xAF, (byte) 0x55, (byte) 0xD5, (byte) 0xEF, (byte) 0x1A, (byte) 0x7C,
(byte) 0xA7, (byte) 0x5B, (byte) 0xA6, (byte) 0x6F, (byte) 0x86, (byte) 0x9F, (byte) 0x73, (byte) 0xE6,
(byte) 0x0A, (byte) 0xDE, (byte) 0x2B, (byte) 0x99, (byte) 0x4A, (byte) 0x47, (byte) 0x9C, (byte) 0xDF,
(byte) 0x09, (byte) 0x76, (byte) 0x9E, (byte) 0x30, (byte) 0x0E, (byte) 0xE4, (byte) 0xB2, (byte) 0x94,
(byte) 0xA0, (byte) 0x3B, (byte) 0x34, (byte) 0x1D, (byte) 0x28, (byte) 0x0F, (byte) 0x36, (byte) 0xE3,
(byte) 0x23, (byte) 0xB4, (byte) 0x03, (byte) 0xD8, (byte) 0x90, (byte) 0xC8, (byte) 0x3C, (byte) 0xFE,
(byte) 0x5E, (byte) 0x32, (byte) 0x24, (byte) 0x50, (byte) 0x1F, (byte) 0x3A, (byte) 0x43, (byte) 0x8A,
(byte) 0x96, (byte) 0x41, (byte) 0x74, (byte) 0xAC, (byte) 0x52, (byte) 0x33, (byte) 0xF0, (byte) 0xD9,
(byte) 0x29, (byte) 0x80, (byte) 0xB1, (byte) 0x16, (byte) 0xD3, (byte) 0xAB, (byte) 0x91, (byte) 0xB9,
(byte) 0x84, (byte) 0x7F, (byte) 0x61, (byte) 0x1E, (byte) 0xCF, (byte) 0xC5, (byte) 0xD1, (byte) 0x56,
(byte) 0x3D, (byte) 0xCA, (byte) 0xF4, (byte) 0x05, (byte) 0xC6, (byte) 0xE5, (byte) 0x08, (byte) 0x49 };
private static final byte[] SHUFFLE_IV = { (byte) 0xF2, (byte) 0x53, (byte) 0x50, (byte) 0xC6 };
private static final byte[] AES_KEY = { (byte) 0x13, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x08, (byte) 0x00, (byte) 0x00, (byte) 0x00,
(byte) 0x06, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0xB4, (byte) 0x00, (byte) 0x00, (byte) 0x00,
(byte) 0x1B, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x0F, (byte) 0x00, (byte) 0x00, (byte) 0x00,
(byte) 0x33, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x52, (byte) 0x00, (byte) 0x00, (byte) 0x00 };
private static final Cipher cipher;
static {
Security.addProvider(new BouncyCastleProvider());
try {
cipher = Cipher.getInstance("AES/ECB/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(AES_KEY, "AES"));
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
private byte[] iv;
private short version;
/**
* Class constructor.
*
* @param iv
* the initialization vector
* @param version
* the game version
* @param versionType
* the version representation type
*
* @throws NullPointerException
* if any of the arguments is null.
* @throws IllegalArgumentException
* if the array 'iv' doesn't have exactly 4 elements.
*
* @see VersionType
*/
public AesTransform(final byte[] iv, final short version, final VersionType versionType) {
checkNotNull(iv);
checkNotNull(version);
checkNotNull(versionType);
checkArgument(iv.length == 4, "'iv' must have exactly 4 elements.");
this.iv = new byte[4];
System.arraycopy(this.iv, 0, iv, 0, 4);
if (versionType == VersionType.COMPLEMENT) {
this.version = (short) ~version;
}
this.version = (short) (this.version >> 8 | (this.version & 0xFF) << 8);
}
/**
* Determines whether the specified byte array has a valid header.
*
* @param header
* the byte array to check
* @return true if the header is valid; otherwise, false.
*/
public boolean validateHeader(final byte[] header) {
final short extractedVersion = getVersion(header, this.iv);
return extractedVersion == this.version;
}
/**
* Constructs a header for a packet.
*
* @param length
* the length of the packet
* @return a 4-element byte array
*
* @throws IllegalArgumentException
* if the 'length' is less than 2.
*/
public byte[] constructHeader(final int length) {
checkArgument(length >= 2);
final int encodedVersion = (this.iv[2] << 8 | this.iv[3] & 0xFF) ^ this.version;
final int encodedLength = encodedVersion ^ ((length & 0xFF) << 8 | length >> 8);
final byte[] header = new byte[4];
header[0] = (byte) (encodedVersion >> 8);
header[1] = (byte) encodedVersion;
header[2] = (byte) (encodedLength >> 8);
header[3] = (byte) encodedLength;
return header;
}
/**
* Applies the cryptographic transformation to an array. The given array
* will be modified.
*
* @param data
* the array to transform.
*
* @throws NullPointerException
* if 'data' is <code>null</code>
*/
public void transform(final byte[] data) {
checkNotNull(data);
transformArraySegment(data, this.iv, 0, data.length);
this.updateIv();
}
private void updateIv() {
final byte[] newIv = new byte[4];
System.arraycopy(SHUFFLE_IV, 0, newIv, 0, 4);
for (int i = 0; i < 4; i++) {
final byte input = this.iv[i], tableInput = SHUFFLE_TABLE[input];
newIv[0] += (byte) (SHUFFLE_TABLE[newIv[1]] - input);
newIv[1] -= (byte) (newIv[2] ^ tableInput);
newIv[2] ^= (byte) (SHUFFLE_TABLE[newIv[3]] + input);
newIv[3] -= (byte) (newIv[0] - tableInput);
final int merged = newIv[3] << 24 | newIv[2] << 16 | newIv[1] << 8 | newIv[0];
final int shifted = merged << 3 | merged >> 0x1D;
newIv[0] = (byte) shifted;
newIv[1] = (byte) (shifted >> 8);
newIv[2] = (byte) (shifted >> 16);
newIv[3] = (byte) (shifted >> 24);
}
this.iv = newIv;
}
/**
* Applies the cryptographic transformation to an array.
*
* @param data
* the array to transform
* @param iv
* the initialization vector to use for the transformation.
* @return the transformed array.
*/
public static byte[] transformWithIv(final byte[] data, final byte[] iv) {
final int length = data.length;
final byte[] transformedData = new byte[length];
System.arraycopy(data, 0, transformedData, 0, length);
transformArraySegment(data, iv, 0, length);
return transformedData;
}
/**
* Decodes the packet length of a packet.
*
* @param data
* the packet byte array, including header
* @return the decoded length
*
* @throws NullPointerException
* if 'data' is <code>null</code>
* @throws IllegalArgumentException
* if 'data' has less than 4 elements.
*/
public static int getPacketLength(final byte[] data) {
checkNotNull(data);
checkArgument(data.length >= 4, "'data' must have at least 4 elements.");
return (data[1] ^ data[3]) << 8 | data[0] ^ data[2];
}
/**
* Extracts a version number from a packet.
*
* @param data
* the packet byte array, including header
* @param iv
* the initialization vector to use
* @return the extracted version
*
* @throws NullPointerException
* if 'data' is <code>null</code>
* @throws IllegalArgumentException
* if 'data' has less than 4 elements.
*/
public static short getVersion(final byte[] data, final byte[] iv) {
checkNotNull(iv);
checkArgument(data.length >= 4, "'data' must have at least 4 elements.");
final short encodedVersion = (short) (data[0] << 8 | data[1] & 0xFF);
final short xorSegment = (short) (iv[2] << 8 | iv[3] & 0xFF);
return (short) (encodedVersion ^ xorSegment);
}
private static void transformArraySegment(final byte[] data, final byte[] iv, final int segmentStart, final int segmentEnd) {
final byte[] xorBlock = new byte[IV_LENGTH];
// First block is 4 elements shorter because of the header.
final int FIRST_BLOCK_LENGTH = BLOCK_LENGTH - 4;
int blockStart = segmentStart;
int blockEnd = Math.min(blockStart + FIRST_BLOCK_LENGTH, segmentEnd);
transformBlock(data, iv, blockStart, blockEnd, xorBlock);
blockStart += FIRST_BLOCK_LENGTH;
while (blockStart < segmentEnd) {
blockEnd = Math.min(blockStart + BLOCK_LENGTH, segmentEnd);
transformBlock(data, iv, blockStart, blockEnd, xorBlock);
blockStart += BLOCK_LENGTH;
}
}
private static void transformBlock(final byte[] data, final byte[] iv, final int blockStart, final int blockEnd, byte[] xorBlock) {
fillXorBlock(iv, xorBlock);
int xorBlockPosition = 0;
for (int position = blockStart; position < blockEnd; position++) {
if (xorBlockPosition == 0) {
try {
xorBlock = cipher.doFinal(xorBlock, 0, IV_LENGTH);
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
data[position] ^= xorBlock[xorBlockPosition++];
if (xorBlockPosition == IV_LENGTH) {
xorBlockPosition = 0;
}
}
}
private static void fillXorBlock(final byte[] iv, final byte[] xorBlock) {
for (int i = 0; i < IV_LENGTH; i += 4) {
System.arraycopy(iv, 0, xorBlock, i, 4);
}
}
/**
* Returns the IV of this instance as a string.
*/
@Override
public String toString() {
return "IV: " + HexTool.toString(this.iv);
}
}