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	/*
	* Copyright (c) 2004, 2008, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	*/

	package sun.security.krb5.internal.crypto.dk;

	import javax.crypto.Cipher;
	import javax.crypto.Mac;
	import javax.crypto.SecretKeyFactory;
	import javax.crypto.SecretKey;
	import javax.crypto.spec.SecretKeySpec;
	import javax.crypto.spec.DESedeKeySpec;
	import javax.crypto.spec.IvParameterSpec;
	import javax.crypto.spec.PBEKeySpec;
	import java.security.spec.KeySpec;
	import java.security.GeneralSecurityException;
	import sun.security.krb5.KrbCryptoException;
	import sun.security.krb5.Confounder;
	import sun.security.krb5.internal.crypto.KeyUsage;
	import java.util.Arrays;

	/**
	* This class provides the implementation of AES Encryption for Kerberos
	* as defined RFC 3962.
	* http://www.ietf.org/rfc/rfc3962.txt
	*
	* Algorithm profile described in [KCRYPTO]:
	* +--------------------------------------------------------------------+
	* \| protocol key format 128- or 256-bit string \|
	* \| \|
	* \| string-to-key function PBKDF2+DK with variable \|
	* \| iteration count (see \|
	* \| above) \|
	* \| \|
	* \| default string-to-key parameters 00 00 10 00 \|
	* \| \|
	* \| key-generation seed length key size \|
	* \| \|
	* \| random-to-key function identity function \|
	* \| \|
	* \| hash function, H SHA-1 \|
	* \| \|
	* \| HMAC output size, h 12 octets (96 bits) \|
	* \| \|
	* \| message block size, m 1 octet \|
	* \| \|
	* \| encryption/decryption functions, AES in CBC-CTS mode \|
	* \| E and D (cipher block size 16 \|
	* \| octets), with next to \|
	* \| last block as CBC-style \|
	* \| ivec \|
	* +--------------------------------------------------------------------+
	*
	* Supports AES128 and AES256
	*
	* @author Seema Malkani
	*/

	public class AesDkCrypto extends DkCrypto {

	private static final boolean debug = false;

	private static final int BLOCK_SIZE = 16;
	private static final int DEFAULT_ITERATION_COUNT = 4096;
	private static final byte[] ZERO_IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0 };
	private static final int hashSize = 96/8;
	private final int keyLength;

	public AesDkCrypto(int length) {
	keyLength = length;
	}

	protected int getKeySeedLength() {
	return keyLength; // bits; AES key material
	}

	public byte[] stringToKey(char[] password, String salt, byte[] s2kparams)
	throws GeneralSecurityException {

	byte[] saltUtf8 = null;
	try {
	saltUtf8 = salt.getBytes("UTF-8");
	return stringToKey(password, saltUtf8, s2kparams);
	} catch (Exception e) {
	return null;
	} finally {
	if (saltUtf8 != null) {
	Arrays.fill(saltUtf8, (byte)0);
	}
	}
	}

	private byte[] stringToKey(char[] secret, byte[] salt, byte[] params)
	throws GeneralSecurityException {

	int iter_count = DEFAULT_ITERATION_COUNT;
	if (params != null) {
	if (params.length != 4) {
	throw new RuntimeException("Invalid parameter to stringToKey");
	}
	iter_count = readBigEndian(params, 0, 4);
	}

	byte[] tmpKey = randomToKey(PBKDF2(secret, salt, iter_count,
	getKeySeedLength()));
	byte[] result = dk(tmpKey, KERBEROS_CONSTANT);
	return result;
	}

	protected byte[] randomToKey(byte[] in) {
	// simple identity operation
	return in;
	}

	protected Cipher getCipher(byte[] key, byte[] ivec, int mode)
	throws GeneralSecurityException {

	// IV
	if (ivec == null) {
	ivec = ZERO_IV;
	}
	SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
	Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
	IvParameterSpec encIv = new IvParameterSpec(ivec, 0, ivec.length);
	cipher.init(mode, secretKey, encIv);
	return cipher;
	}

	// get an instance of the AES Cipher in CTS mode
	public int getChecksumLength() {
	return hashSize; // bytes
	}

	/**
	* Get the truncated HMAC
	*/
	protected byte[] getHmac(byte[] key, byte[] msg)
	throws GeneralSecurityException {

	SecretKey keyKi = new SecretKeySpec(key, "HMAC");
	Mac m = Mac.getInstance("HmacSHA1");
	m.init(keyKi);

	// generate hash
	byte[] hash = m.doFinal(msg);

	// truncate hash
	byte[] output = new byte[hashSize];
	System.arraycopy(hash, 0, output, 0, hashSize);
	return output;
	}

	/**
	* Calculate the checksum
	*/
	public byte[] calculateChecksum(byte[] baseKey, int usage, byte[] input,
	int start, int len) throws GeneralSecurityException {

	if (!KeyUsage.isValid(usage)) {
	throw new GeneralSecurityException("Invalid key usage number: "
	+ usage);
	}

	// Derive keys
	byte[] constant = new byte[5];
	constant[0] = (byte) ((usage>>24)&0xff);
	constant[1] = (byte) ((usage>>16)&0xff);
	constant[2] = (byte) ((usage>>8)&0xff);
	constant[3] = (byte) (usage&0xff);

	constant[4] = (byte) 0x99;

	byte[] Kc = dk(baseKey, constant); // Checksum key
	if (debug) {
	System.err.println("usage: " + usage);
	traceOutput("input", input, start, Math.min(len, 32));
	traceOutput("constant", constant, 0, constant.length);
	traceOutput("baseKey", baseKey, 0, baseKey.length);
	traceOutput("Kc", Kc, 0, Kc.length);
	}

	try {
	// Generate checksum
	// H1 = HMAC(Kc, input)
	byte[] hmac = getHmac(Kc, input);
	if (debug) {
	traceOutput("hmac", hmac, 0, hmac.length);
	}
	if (hmac.length == getChecksumLength()) {
	return hmac;
	} else if (hmac.length > getChecksumLength()) {
	byte[] buf = new byte[getChecksumLength()];
	System.arraycopy(hmac, 0, buf, 0, buf.length);
	return buf;
	} else {
	throw new GeneralSecurityException("checksum size too short: " +
	hmac.length + "; expecting : " + getChecksumLength());
	}
	} finally {
	Arrays.fill(Kc, 0, Kc.length, (byte)0);
	}
	}

	/**
	* Performs encryption using derived key; adds confounder.
	*/
	public byte[] encrypt(byte[] baseKey, int usage,
	byte[] ivec, byte[] new_ivec, byte[] plaintext, int start, int len)
	throws GeneralSecurityException, KrbCryptoException {

	if (!KeyUsage.isValid(usage)) {
	throw new GeneralSecurityException("Invalid key usage number: "
	+ usage);
	}
	byte[] output = encryptCTS(baseKey, usage, ivec, new_ivec, plaintext,
	start, len, true);
	return output;
	}

	/**
	* Performs encryption using derived key; does not add confounder.
	*/
	public byte[] encryptRaw(byte[] baseKey, int usage,
	byte[] ivec, byte[] plaintext, int start, int len)
	throws GeneralSecurityException, KrbCryptoException {

	if (!KeyUsage.isValid(usage)) {
	throw new GeneralSecurityException("Invalid key usage number: "
	+ usage);
	}
	byte[] output = encryptCTS(baseKey, usage, ivec, null, plaintext,
	start, len, false);
	return output;
	}

	/**
	* @param baseKey key from which keys are to be derived using usage
	* @param ciphertext E(Ke, conf \| plaintext \| padding, ivec) \| H1[1..h]
	*/
	public byte[] decrypt(byte[] baseKey, int usage, byte[] ivec,
	byte[] ciphertext, int start, int len) throws GeneralSecurityException {

	if (!KeyUsage.isValid(usage)) {
	throw new GeneralSecurityException("Invalid key usage number: "
	+ usage);
	}
	byte[] output = decryptCTS(baseKey, usage, ivec, ciphertext,
	start, len, true);
	return output;
	}

	/**
	* Decrypts data using specified key and initial vector.
	* @param baseKey encryption key to use
	* @param ciphertext encrypted data to be decrypted
	* @param usage ignored
	*/
	public byte[] decryptRaw(byte[] baseKey, int usage, byte[] ivec,
	byte[] ciphertext, int start, int len)
	throws GeneralSecurityException {

	if (!KeyUsage.isValid(usage)) {
	throw new GeneralSecurityException("Invalid key usage number: "
	+ usage);
	}
	byte[] output = decryptCTS(baseKey, usage, ivec, ciphertext,
	start, len, false);
	return output;
	}

	/**
	* Encrypt AES in CBC-CTS mode using derived keys.
	*/
	private byte[] encryptCTS(byte[] baseKey, int usage, byte[] ivec,
	byte[] new_ivec, byte[] plaintext, int start, int len,
	boolean confounder_exists)
	throws GeneralSecurityException, KrbCryptoException {

	byte[] Ke = null;
	byte[] Ki = null;

	if (debug) {
	System.err.println("usage: " + usage);
	if (ivec != null) {
	traceOutput("old_state.ivec", ivec, 0, ivec.length);
	}
	traceOutput("plaintext", plaintext, start, Math.min(len, 32));
	traceOutput("baseKey", baseKey, 0, baseKey.length);
	}

	try {
	// derive Encryption key
	byte[] constant = new byte[5];
	constant[0] = (byte) ((usage>>24)&0xff);
	constant[1] = (byte) ((usage>>16)&0xff);
	constant[2] = (byte) ((usage>>8)&0xff);
	constant[3] = (byte) (usage&0xff);
	constant[4] = (byte) 0xaa;
	Ke = dk(baseKey, constant); // Encryption key

	byte[] toBeEncrypted = null;
	if (confounder_exists) {
	byte[] confounder = Confounder.bytes(BLOCK_SIZE);
	toBeEncrypted = new byte[confounder.length + len];
	System.arraycopy(confounder, 0, toBeEncrypted,
	0, confounder.length);
	System.arraycopy(plaintext, start, toBeEncrypted,
	confounder.length, len);
	} else {
	toBeEncrypted = new byte[len];
	System.arraycopy(plaintext, start, toBeEncrypted, 0, len);
	}

	// encryptedData + HMAC
	byte[] output = new byte[toBeEncrypted.length + hashSize];

	// AES in JCE
	Cipher cipher = Cipher.getInstance("AES/CTS/NoPadding");
	SecretKeySpec secretKey = new SecretKeySpec(Ke, "AES");
	IvParameterSpec encIv = new IvParameterSpec(ivec, 0, ivec.length);
	cipher.init(Cipher.ENCRYPT_MODE, secretKey, encIv);
	cipher.doFinal(toBeEncrypted, 0, toBeEncrypted.length, output);

	// Derive integrity key
	constant[4] = (byte) 0x55;
	Ki = dk(baseKey, constant);
	if (debug) {
	traceOutput("constant", constant, 0, constant.length);
	traceOutput("Ki", Ki, 0, Ke.length);
	}

	// Generate checksum
	// H1 = HMAC(Ki, conf \| plaintext \| pad)
	byte[] hmac = getHmac(Ki, toBeEncrypted);

	// encryptedData + HMAC
	System.arraycopy(hmac, 0, output, toBeEncrypted.length,
	hmac.length);
	return output;
	} finally {
	if (Ke != null) {
	Arrays.fill(Ke, 0, Ke.length, (byte) 0);
	}
	if (Ki != null) {
	Arrays.fill(Ki, 0, Ki.length, (byte) 0);
	}
	}
	}

	/**
	* Decrypt AES in CBC-CTS mode using derived keys.
	*/
	private byte[] decryptCTS(byte[] baseKey, int usage, byte[] ivec,
	byte[] ciphertext, int start, int len, boolean confounder_exists)
	throws GeneralSecurityException {

	byte[] Ke = null;
	byte[] Ki = null;

	try {
	// Derive encryption key
	byte[] constant = new byte[5];
	constant[0] = (byte) ((usage>>24)&0xff);
	constant[1] = (byte) ((usage>>16)&0xff);
	constant[2] = (byte) ((usage>>8)&0xff);
	constant[3] = (byte) (usage&0xff);

	constant[4] = (byte) 0xaa;
	Ke = dk(baseKey, constant); // Encryption key

	if (debug) {
	System.err.println("usage: " + usage);
	if (ivec != null) {
	traceOutput("old_state.ivec", ivec, 0, ivec.length);
	}
	traceOutput("ciphertext", ciphertext, start, Math.min(len, 32));
	traceOutput("constant", constant, 0, constant.length);
	traceOutput("baseKey", baseKey, 0, baseKey.length);
	traceOutput("Ke", Ke, 0, Ke.length);
	}

	// Decrypt [confounder \| plaintext ] (without checksum)

	// AES in JCE
	Cipher cipher = Cipher.getInstance("AES/CTS/NoPadding");
	SecretKeySpec secretKey = new SecretKeySpec(Ke, "AES");
	IvParameterSpec encIv = new IvParameterSpec(ivec, 0, ivec.length);
	cipher.init(Cipher.DECRYPT_MODE, secretKey, encIv);
	byte[] plaintext = cipher.doFinal(ciphertext, start, len-hashSize);

	if (debug) {
	traceOutput("AES PlainText", plaintext, 0,
	Math.min(plaintext.length, 32));
	}

	// Derive integrity key
	constant[4] = (byte) 0x55;
	Ki = dk(baseKey, constant); // Integrity key
	if (debug) {
	traceOutput("constant", constant, 0, constant.length);
	traceOutput("Ki", Ki, 0, Ke.length);
	}

	// Verify checksum
	// H1 = HMAC(Ki, conf \| plaintext \| pad)
	byte[] calculatedHmac = getHmac(Ki, plaintext);
	int hmacOffset = start + len - hashSize;
	if (debug) {
	traceOutput("calculated Hmac", calculatedHmac,
	0, calculatedHmac.length);
	traceOutput("message Hmac", ciphertext, hmacOffset, hashSize);
	}
	boolean cksumFailed = false;
	if (calculatedHmac.length >= hashSize) {
	for (int i = 0; i < hashSize; i++) {
	if (calculatedHmac[i] != ciphertext[hmacOffset+i]) {
	cksumFailed = true;
	if (debug) {
	System.err.println("Checksum failed !");
	}
	break;
	}
	}
	}
	if (cksumFailed) {
	throw new GeneralSecurityException("Checksum failed");
	}

	if (confounder_exists) {
	// Get rid of confounder
	// [ confounder \| plaintext ]
	byte[] output = new byte[plaintext.length - BLOCK_SIZE];
	System.arraycopy(plaintext, BLOCK_SIZE, output,
	0, output.length);
	return output;
	} else {
	return plaintext;
	}
	} finally {
	if (Ke != null) {
	Arrays.fill(Ke, 0, Ke.length, (byte) 0);
	}
	if (Ki != null) {
	Arrays.fill(Ki, 0, Ki.length, (byte) 0);
	}
	}
	}

	/*
	* Invoke the PKCS#5 PBKDF2 algorithm
	*/
	private static byte[] PBKDF2(char[] secret, byte[] salt,
	int count, int keyLength) throws GeneralSecurityException {

	PBEKeySpec keySpec = new PBEKeySpec(secret, salt, count, keyLength);
	SecretKeyFactory skf =
	SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
	SecretKey key = skf.generateSecret(keySpec);
	byte[] result = key.getEncoded();

	return result;
	}

	public static final int readBigEndian(byte[] data, int pos, int size) {
	int retVal = 0;
	int shifter = (size-1)*8;
	while (size > 0) {
	retVal += (data[pos] & 0xff) << shifter;
	shifter -= 8;
	pos++;
	size--;
	}
	return retVal;
	}

	}

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