483 lines
16 KiB
Java
483 lines
16 KiB
Java
/*
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* Copyright (c) 2005, 2008, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.security.krb5.internal.crypto.dk;
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import java.security.*;
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import javax.crypto.*;
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import javax.crypto.spec.*;
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import java.util.*;
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import sun.security.krb5.EncryptedData;
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import sun.security.krb5.KrbCryptoException;
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import sun.security.krb5.Confounder;
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import sun.security.krb5.internal.crypto.KeyUsage;
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/**
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* Support for ArcFour in Kerberos
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* as defined in RFC 4757.
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* http://www.ietf.org/rfc/rfc4757.txt
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*
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* @author Seema Malkani
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*/
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public class ArcFourCrypto extends DkCrypto {
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private static final boolean debug = false;
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private static final int confounderSize = 8;
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private static final byte[] ZERO_IV = new byte[] {0, 0, 0, 0, 0, 0, 0, 0};
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private static final int hashSize = 16;
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private final int keyLength;
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public ArcFourCrypto(int length) {
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keyLength = length;
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}
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protected int getKeySeedLength() {
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return keyLength; // bits; RC4 key material
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}
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protected byte[] randomToKey(byte[] in) {
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// simple identity operation
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return in;
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}
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public byte[] stringToKey(char[] passwd)
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throws GeneralSecurityException {
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return stringToKey(passwd, null);
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}
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/*
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* String2Key(Password)
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* K = MD4(UNICODE(password))
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*/
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private byte[] stringToKey(char[] secret, byte[] opaque)
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throws GeneralSecurityException {
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if (opaque != null && opaque.length > 0) {
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throw new RuntimeException("Invalid parameter to stringToKey");
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}
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byte[] passwd = null;
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byte[] digest = null;
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try {
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// convert ascii to unicode
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passwd = charToUtf16(secret);
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// provider for MD4
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MessageDigest md = sun.security.provider.MD4.getInstance();
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md.update(passwd);
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digest = md.digest();
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} catch (Exception e) {
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return null;
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} finally {
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if (passwd != null) {
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Arrays.fill(passwd, (byte)0);
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}
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}
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return digest;
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}
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protected Cipher getCipher(byte[] key, byte[] ivec, int mode)
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throws GeneralSecurityException {
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// IV
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if (ivec == null) {
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ivec = ZERO_IV;
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}
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SecretKeySpec secretKey = new SecretKeySpec(key, "ARCFOUR");
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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IvParameterSpec encIv = new IvParameterSpec(ivec, 0, ivec.length);
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cipher.init(mode, secretKey, encIv);
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return cipher;
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}
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public int getChecksumLength() {
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return hashSize; // bytes
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}
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/**
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* Get the HMAC-MD5
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*/
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protected byte[] getHmac(byte[] key, byte[] msg)
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throws GeneralSecurityException {
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SecretKey keyKi = new SecretKeySpec(key, "HmacMD5");
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Mac m = Mac.getInstance("HmacMD5");
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m.init(keyKi);
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// generate hash
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byte[] hash = m.doFinal(msg);
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return hash;
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}
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/**
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* Calculate the checksum
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*/
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public byte[] calculateChecksum(byte[] baseKey, int usage, byte[] input,
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int start, int len) throws GeneralSecurityException {
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if (debug) {
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System.out.println("ARCFOUR: calculateChecksum with usage = " +
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usage);
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}
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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byte[] Ksign = null;
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// Derive signing key from session key
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try {
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byte[] ss = "signaturekey".getBytes();
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// need to append end-of-string 00
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byte[] new_ss = new byte[ss.length+1];
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System.arraycopy(ss, 0, new_ss, 0, ss.length);
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Ksign = getHmac(baseKey, new_ss);
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} catch (Exception e) {
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GeneralSecurityException gse =
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new GeneralSecurityException("Calculate Checkum Failed!");
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gse.initCause(e);
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throw gse;
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}
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// get the salt using key usage
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byte[] salt = getSalt(usage);
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// Generate checksum of message
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MessageDigest messageDigest = null;
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try {
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messageDigest = MessageDigest.getInstance("MD5");
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} catch (NoSuchAlgorithmException e) {
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GeneralSecurityException gse =
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new GeneralSecurityException("Calculate Checkum Failed!");
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gse.initCause(e);
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throw gse;
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}
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messageDigest.update(salt);
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messageDigest.update(input, start, len);
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byte[] md5tmp = messageDigest.digest();
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// Generate checksum
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byte[] hmac = getHmac(Ksign, md5tmp);
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if (debug) {
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traceOutput("hmac", hmac, 0, hmac.length);
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}
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if (hmac.length == getChecksumLength()) {
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return hmac;
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} else if (hmac.length > getChecksumLength()) {
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byte[] buf = new byte[getChecksumLength()];
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System.arraycopy(hmac, 0, buf, 0, buf.length);
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return buf;
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} else {
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throw new GeneralSecurityException("checksum size too short: " +
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hmac.length + "; expecting : " + getChecksumLength());
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}
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}
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/**
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* Performs encryption of Sequence Number using derived key.
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*/
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public byte[] encryptSeq(byte[] baseKey, int usage,
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byte[] checksum, byte[] plaintext, int start, int len)
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throws GeneralSecurityException, KrbCryptoException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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// derive encryption for sequence number
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byte[] salt = new byte[4];
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byte[] kSeq = getHmac(baseKey, salt);
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// derive new encryption key salted with sequence number
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kSeq = getHmac(kSeq, checksum);
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(kSeq, "ARCFOUR");
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cipher.init(Cipher.ENCRYPT_MODE, secretKey);
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byte[] output = cipher.doFinal(plaintext, start, len);
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return output;
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}
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/**
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* Performs decryption of Sequence Number using derived key.
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*/
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public byte[] decryptSeq(byte[] baseKey, int usage,
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byte[] checksum, byte[] ciphertext, int start, int len)
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throws GeneralSecurityException, KrbCryptoException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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// derive decryption for sequence number
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byte[] salt = new byte[4];
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byte[] kSeq = getHmac(baseKey, salt);
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// derive new encryption key salted with sequence number
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kSeq = getHmac(kSeq, checksum);
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(kSeq, "ARCFOUR");
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cipher.init(Cipher.DECRYPT_MODE, secretKey);
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byte[] output = cipher.doFinal(ciphertext, start, len);
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return output;
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}
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/**
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* Performs encryption using derived key; adds confounder.
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*/
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public byte[] encrypt(byte[] baseKey, int usage,
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byte[] ivec, byte[] new_ivec, byte[] plaintext, int start, int len)
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throws GeneralSecurityException, KrbCryptoException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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if (debug) {
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System.out.println("ArcFour: ENCRYPT with key usage = " + usage);
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}
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// get the confounder
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byte[] confounder = Confounder.bytes(confounderSize);
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// add confounder to the plaintext for encryption
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int plainSize = roundup(confounder.length + len, 1);
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byte[] toBeEncrypted = new byte[plainSize];
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System.arraycopy(confounder, 0, toBeEncrypted, 0, confounder.length);
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System.arraycopy(plaintext, start, toBeEncrypted,
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confounder.length, len);
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/* begin the encryption, compute K1 */
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byte[] k1 = new byte[baseKey.length];
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System.arraycopy(baseKey, 0, k1, 0, baseKey.length);
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// get the salt using key usage
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byte[] salt = getSalt(usage);
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// compute K2 using K1
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byte[] k2 = getHmac(k1, salt);
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// generate checksum using K2
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byte[] checksum = getHmac(k2, toBeEncrypted);
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// compute K3 using K2 and checksum
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byte[] k3 = getHmac(k2, checksum);
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(k3, "ARCFOUR");
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cipher.init(Cipher.ENCRYPT_MODE, secretKey);
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byte[] output = cipher.doFinal(toBeEncrypted, 0, toBeEncrypted.length);
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// encryptedData + HMAC
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byte[] result = new byte[hashSize + output.length];
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System.arraycopy(checksum, 0, result, 0, hashSize);
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System.arraycopy(output, 0, result, hashSize, output.length);
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return result;
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}
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/**
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* Performs encryption using derived key; does not add confounder.
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*/
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public byte[] encryptRaw(byte[] baseKey, int usage,
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byte[] seqNum, byte[] plaintext, int start, int len)
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throws GeneralSecurityException, KrbCryptoException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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if (debug) {
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System.out.println("\nARCFOUR: encryptRaw with usage = " + usage);
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}
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// Derive encryption key for data
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// Key derivation salt = 0
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byte[] klocal = new byte[baseKey.length];
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for (int i = 0; i <= 15; i++) {
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klocal[i] = (byte) (baseKey[i] ^ 0xF0);
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}
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byte[] salt = new byte[4];
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byte[] kcrypt = getHmac(klocal, salt);
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// Note: When using this RC4 based encryption type, the sequence number
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// is always sent in big-endian rather than little-endian order.
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// new encryption key salted with sequence number
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kcrypt = getHmac(kcrypt, seqNum);
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(kcrypt, "ARCFOUR");
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cipher.init(Cipher.ENCRYPT_MODE, secretKey);
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byte[] output = cipher.doFinal(plaintext, start, len);
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return output;
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}
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/**
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* @param baseKey key from which keys are to be derived using usage
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* @param ciphertext E(Ke, conf | plaintext | padding, ivec) | H1[1..h]
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*/
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public byte[] decrypt(byte[] baseKey, int usage, byte[] ivec,
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byte[] ciphertext, int start, int len)
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throws GeneralSecurityException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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if (debug) {
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System.out.println("\nARCFOUR: DECRYPT using key usage = " + usage);
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}
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// compute K1
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byte[] k1 = new byte[baseKey.length];
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System.arraycopy(baseKey, 0, k1, 0, baseKey.length);
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// get the salt using key usage
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byte[] salt = getSalt(usage);
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// compute K2 using K1
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byte[] k2 = getHmac(k1, salt);
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// compute K3 using K2 and checksum
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byte[] checksum = new byte[hashSize];
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System.arraycopy(ciphertext, start, checksum, 0, hashSize);
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byte[] k3 = getHmac(k2, checksum);
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// Decrypt [confounder | plaintext ] (without checksum)
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(k3, "ARCFOUR");
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cipher.init(Cipher.DECRYPT_MODE, secretKey);
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byte[] plaintext = cipher.doFinal(ciphertext, start+hashSize,
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len-hashSize);
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// Verify checksum
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byte[] calculatedHmac = getHmac(k2, plaintext);
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if (debug) {
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traceOutput("calculated Hmac", calculatedHmac, 0,
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calculatedHmac.length);
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traceOutput("message Hmac", ciphertext, 0,
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hashSize);
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}
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boolean cksumFailed = false;
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if (calculatedHmac.length >= hashSize) {
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for (int i = 0; i < hashSize; i++) {
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if (calculatedHmac[i] != ciphertext[i]) {
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cksumFailed = true;
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if (debug) {
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System.err.println("Checksum failed !");
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}
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break;
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}
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}
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}
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if (cksumFailed) {
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throw new GeneralSecurityException("Checksum failed");
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}
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// Get rid of confounder
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// [ confounder | plaintext ]
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byte[] output = new byte[plaintext.length - confounderSize];
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System.arraycopy(plaintext, confounderSize, output, 0, output.length);
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return output;
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}
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/**
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* Decrypts data using specified key and initial vector.
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* @param baseKey encryption key to use
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* @param ciphertext encrypted data to be decrypted
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* @param usage ignored
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*/
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public byte[] decryptRaw(byte[] baseKey, int usage, byte[] ivec,
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byte[] ciphertext, int start, int len, byte[] seqNum)
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throws GeneralSecurityException {
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if (!KeyUsage.isValid(usage)) {
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throw new GeneralSecurityException("Invalid key usage number: "
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+ usage);
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}
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if (debug) {
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System.out.println("\nARCFOUR: decryptRaw with usage = " + usage);
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}
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// Derive encryption key for data
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// Key derivation salt = 0
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byte[] klocal = new byte[baseKey.length];
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for (int i = 0; i <= 15; i++) {
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klocal[i] = (byte) (baseKey[i] ^ 0xF0);
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}
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byte[] salt = new byte[4];
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byte[] kcrypt = getHmac(klocal, salt);
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// need only first 4 bytes of sequence number
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byte[] sequenceNum = new byte[4];
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System.arraycopy(seqNum, 0, sequenceNum, 0, sequenceNum.length);
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// new encryption key salted with sequence number
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kcrypt = getHmac(kcrypt, sequenceNum);
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Cipher cipher = Cipher.getInstance("ARCFOUR");
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SecretKeySpec secretKey = new SecretKeySpec(kcrypt, "ARCFOUR");
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cipher.init(Cipher.DECRYPT_MODE, secretKey);
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byte[] output = cipher.doFinal(ciphertext, start, len);
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return output;
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}
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// get the salt using key usage
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private byte[] getSalt(int usage) {
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int ms_usage = arcfour_translate_usage(usage);
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byte[] salt = new byte[4];
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salt[0] = (byte)(ms_usage & 0xff);
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salt[1] = (byte)((ms_usage >> 8) & 0xff);
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salt[2] = (byte)((ms_usage >> 16) & 0xff);
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salt[3] = (byte)((ms_usage >> 24) & 0xff);
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return salt;
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}
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// Key usage translation for MS
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private int arcfour_translate_usage(int usage) {
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switch (usage) {
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case 3: return 8;
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case 9: return 8;
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case 23: return 13;
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default: return usage;
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}
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}
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}
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