/*

 * Portions Copyright 2000-2007 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 *

 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.

 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.

 */

package sun.security.krb5;

import sun.security.util.*;

import sun.security.krb5.internal.*;

import sun.security.krb5.internal.crypto.*;

import java.io.IOException;

import java.security.GeneralSecurityException;

import java.util.Arrays;

import sun.security.krb5.internal.ktab.KeyTab;

import sun.security.krb5.internal.ccache.CCacheOutputStream;

import javax.crypto.spec.DESKeySpec;

import javax.crypto.spec.DESedeKeySpec;

/**

 * This class encapsulates the concept of an EncryptionKey. An encryption

 * key is defined in RFC 4120 as:

 *

 * EncryptionKey   ::= SEQUENCE {

 *         keytype         [0] Int32 -- actually encryption type --,

 *         keyvalue        [1] OCTET STRING

 * }

 *

 * keytype

 *     This field specifies the encryption type of the encryption key

 *     that follows in the keyvalue field.  Although its name is

 *     "keytype", it actually specifies an encryption type.  Previously,

 *     multiple cryptosystems that performed encryption differently but

 *     were capable of using keys with the same characteristics were

 *     permitted to share an assigned number to designate the type of

 *     key; this usage is now deprecated.

 *

 * keyvalue

 *     This field contains the key itself, encoded as an octet string.

 */

public class EncryptionKey

    implements Cloneable {

    public static final EncryptionKey NULL_KEY =

        new EncryptionKey(new byte[] {}, EncryptedData.ETYPE_NULL, null);

    private int keyType;

    private byte[] keyValue;

    private Integer kvno; // not part of ASN1 encoding;

    private static final boolean DEBUG = Krb5.DEBUG;

    public synchronized int getEType() {

        return keyType;

    }

    public final Integer getKeyVersionNumber() {

        return kvno;

    }

    /**

     * Returns the raw key bytes, not in any ASN.1 encoding.

     */

    public final byte[] getBytes() {

        // This method cannot be called outside sun.security, hence no

        // cloning. getEncoded() calls this method.

        return keyValue;

    }

    public synchronized Object clone() {

        return new EncryptionKey(keyValue, keyType, kvno);

    }

    /**

     * Obtains the latest version of the secret key of

     * the principal from a keytab.

     *

     * @param princ the principal whose secret key is desired

     * @param keytab the path to the keytab file. A value of null

     * will be accepted to indicate that the default path should be

     * searched.

     * @returns the secret key or null if none was found.

     */

    /*

    // Replaced by acquireSecretKeys

    public static EncryptionKey acquireSecretKey(PrincipalName princ,

                                                 String keytab)

        throws KrbException, IOException {

        if (princ == null) {

            throw new IllegalArgumentException(

                "Cannot have null pricipal name to look in keytab.");

        }

        KeyTab ktab = KeyTab.getInstance(keytab);

        if (ktab == null)

            return null;

        return ktab.readServiceKey(princ);

    }

    */

    /**

     * Obtains all versions of the secret key of the principal from a

     * keytab.

     *

     * @Param princ the principal whose secret key is desired

     * @param keytab the path to the keytab file. A value of null

     * will be accepted to indicate that the default path should be

     * searched.

     * @returns an array of secret keys or null if none were found.

     */

    public static EncryptionKey[] acquireSecretKeys(PrincipalName princ,

                                                    String keytab)

        throws KrbException, IOException {

        if (princ == null)

            throw new IllegalArgumentException(

                "Cannot have null pricipal name to look in keytab.");

        // KeyTab getInstance(keytab) will call KeyTab.getInstance()

        // if keytab is null

        KeyTab ktab = KeyTab.getInstance(keytab);

        if (ktab == null) {

            return null;

        }

        return ktab.readServiceKeys(princ);

    }

    /**

     * Generate a list of keys using the given principal and password.

     * Construct a key for each configured etype.

     * Caller is responsible for clearing password.

     */

    /*

     * Usually, when keyType is decoded from ASN.1 it will contain a

     * value indicating what the algorithm to be used is. However, when

     * converting from a password to a key for the AS-EXCHANGE, this

     * keyType will not be available. Use builtin list of default etypes

     * as the default in that case. If default_tkt_enctypes was set in

     * the libdefaults of krb5.conf, then use that sequence.

     */

         // Used in Krb5LoginModule

    public static EncryptionKey[] acquireSecretKeys(char[] password,

        String salt) throws KrbException {

        return (acquireSecretKeys(password, salt, false, 0, null));

    }

    /**

     * Generates a list of keys using the given principal, password,

     * and the pre-authentication values.

     */

    public static EncryptionKey[] acquireSecretKeys(char[] password,

        String salt, boolean pa_exists, int pa_etype, byte[] pa_s2kparams)

        throws KrbException {

        int[] etypes = EType.getDefaults("default_tkt_enctypes");

        if (etypes == null) {

            etypes = EType.getBuiltInDefaults();

        }

        // set the preferred etype for preauth

        if ((pa_exists) && (pa_etype != EncryptedData.ETYPE_NULL)) {

            if (DEBUG) {

                System.out.println("Pre-Authentication: " +

                        "Set preferred etype = " + pa_etype);

            }

            if (EType.isSupported(pa_etype)) {

                // reset etypes to preferred value

                etypes = new int[1];

                etypes[0] = pa_etype;

            }

        }

        EncryptionKey[] encKeys = new EncryptionKey[etypes.length];

        for (int i = 0; i < etypes.length; i++) {

            if (EType.isSupported(etypes[i])) {

                encKeys[i] = new EncryptionKey(

                        stringToKey(password, salt, pa_s2kparams, etypes[i]),

                        etypes[i], null);

            } else {

                if (DEBUG) {

                    System.out.println("Encryption Type " +

                        EType.toString(etypes[i]) +

                        " is not supported/enabled");

                }

            }

        }

        return encKeys;

    }

    // Used in Krb5AcceptCredential, self

    public EncryptionKey(byte[] keyValue,

                         int keyType,

                         Integer kvno) {

        if (keyValue != null) {

            this.keyValue = new byte[keyValue.length];

            System.arraycopy(keyValue, 0, this.keyValue, 0, keyValue.length);

        } else {

            throw new IllegalArgumentException("EncryptionKey: " +

                                               "Key bytes cannot be null!");

        }

        this.keyType = keyType;

        this.kvno = kvno;

    }

    /**

     * Constructs an EncryptionKey by using the specified key type and key

     * value.  It is used to recover the key when retrieving data from

     * credential cache file.

     *

     */

     // Used in JSSE (KerberosWrapper), Credentials,

     // javax.security.auth.kerberos.KeyImpl

    public EncryptionKey(int keyType,

                         byte[] keyValue) {

        this(keyValue, keyType, null);

    }

    private static byte[] stringToKey(char[] password, String salt,

        byte[] s2kparams, int keyType) throws KrbCryptoException {

        char[] slt = salt.toCharArray();

        char[] pwsalt = new char[password.length + slt.length];

        System.arraycopy(password, 0, pwsalt, 0, password.length);

        System.arraycopy(slt, 0, pwsalt, password.length, slt.length);

        Arrays.fill(slt, '0');

        try {

            switch (keyType) {

                case EncryptedData.ETYPE_DES_CBC_CRC:

                case EncryptedData.ETYPE_DES_CBC_MD5:

                        return Des.string_to_key_bytes(pwsalt);

                case EncryptedData.ETYPE_DES3_CBC_HMAC_SHA1_KD:

                        return Des3.stringToKey(pwsalt);

                case EncryptedData.ETYPE_ARCFOUR_HMAC:

                        return ArcFourHmac.stringToKey(password);

                case EncryptedData.ETYPE_AES128_CTS_HMAC_SHA1_96:

                        return Aes128.stringToKey(password, salt, s2kparams);

                case EncryptedData.ETYPE_AES256_CTS_HMAC_SHA1_96:

                        return Aes256.stringToKey(password, salt, s2kparams);

                default:

                        throw new IllegalArgumentException("encryption type " +

                        EType.toString(keyType) + " not supported");

            }

        } catch (GeneralSecurityException e) {

            KrbCryptoException ke = new KrbCryptoException(e.getMessage());

            ke.initCause(e);

            throw ke;

        } finally {

            Arrays.fill(pwsalt, '0');

        }

    }

    // Used in javax.security.auth.kerberos.KeyImpl

    public EncryptionKey(char[] password,

                         String salt,

                         String algorithm) throws KrbCryptoException {

        if (algorithm == null || algorithm.equalsIgnoreCase("DES")) {

            keyType = EncryptedData.ETYPE_DES_CBC_MD5;

        } else if (algorithm.equalsIgnoreCase("DESede")) {

            keyType = EncryptedData.ETYPE_DES3_CBC_HMAC_SHA1_KD;

        } else if (algorithm.equalsIgnoreCase("AES128")) {

            keyType = EncryptedData.ETYPE_AES128_CTS_HMAC_SHA1_96;

        } else if (algorithm.equalsIgnoreCase("ArcFourHmac")) {

            keyType = EncryptedData.ETYPE_ARCFOUR_HMAC;

        } else if (algorithm.equalsIgnoreCase("AES256")) {

            keyType = EncryptedData.ETYPE_AES256_CTS_HMAC_SHA1_96;

            // validate if AES256 is enabled

            if (!EType.isSupported(keyType)) {

                throw new IllegalArgumentException("Algorithm " + algorithm +

                        " not enabled");

            }

        } else {

            throw new IllegalArgumentException("Algorithm " + algorithm +

                " not supported");

        }

        keyValue = stringToKey(password, salt, null, keyType);

        kvno = null;

    }

    /**

     * Generates a sub-sessionkey from a given session key.

     */

     // Used in KrbApRep, KrbApReq

    EncryptionKey(EncryptionKey key) throws KrbCryptoException {

        // generate random sub-session key

        keyValue = Confounder.bytes(key.keyValue.length);

        for (int i = 0; i < keyValue.length; i++) {

          keyValue[i] ^= key.keyValue[i];

        }

        keyType = key.keyType;

        // check for key parity and weak keys

        try {

            // check for DES key

            if ((keyType == EncryptedData.ETYPE_DES_CBC_MD5) ||

                (keyType == EncryptedData.ETYPE_DES_CBC_CRC)) {

                // fix DES key parity

                if (!DESKeySpec.isParityAdjusted(keyValue, 0)) {

                    keyValue = Des.set_parity(keyValue);

                }

                // check for weak key

                if (DESKeySpec.isWeak(keyValue, 0)) {

                    keyValue[7] = (byte)(keyValue[7] ^ 0xF0);

                }

            }

            // check for 3DES key

            if (keyType == EncryptedData.ETYPE_DES3_CBC_HMAC_SHA1_KD) {

                // fix 3DES key parity

                if (!DESedeKeySpec.isParityAdjusted(keyValue, 0)) {

                    keyValue = Des3.parityFix(keyValue);

                }

                // check for weak keys

                byte[] oneKey = new byte[8];

                for (int i=0; i<keyValue.length; i+=8) {

                    System.arraycopy(keyValue, i, oneKey, 0, 8);

                    if (DESKeySpec.isWeak(oneKey, 0)) {

                        keyValue[i+7] = (byte)(keyValue[i+7] ^ 0xF0);

                    }

                }

            }

        } catch (GeneralSecurityException e) {

            KrbCryptoException ke = new KrbCryptoException(e.getMessage());

            ke.initCause(e);

            throw ke;

        }

    }

    /**

     * Constructs an instance of EncryptionKey type.

     * @param encoding a single DER-encoded value.

     * @exception Asn1Exception if an error occurs while decoding an ASN1

     * encoded data.

     * @exception IOException if an I/O error occurs while reading encoded

     * data.

     *

     *

     */

         // Used in javax.security.auth.kerberos.KeyImpl

    public EncryptionKey(DerValue encoding) throws Asn1Exception, IOException {

        DerValue der;

        if (encoding.getTag() != DerValue.tag_Sequence) {

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        }

        der = encoding.getData().getDerValue();

        if ((der.getTag() & (byte)0x1F) == (byte)0x00) {

            keyType = der.getData().getBigInteger().intValue();

        }

        else

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        der = encoding.getData().getDerValue();

        if ((der.getTag() & (byte)0x1F) == (byte)0x01) {

            keyValue = der.getData().getOctetString();

        }

        else

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        if (der.getData().available() > 0) {

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        }

    }

    /**

     * Returns the ASN.1 encoding of this EncryptionKey.

     *

     * <xmp>

     * EncryptionKey ::=   SEQUENCE {

     *                             keytype[0]    INTEGER,

     *                             keyvalue[1]   OCTET STRING }

     * </xmp>

     *

     * <p>

     * This definition reflects the Network Working Group RFC 4120

     * specification available at

     * <a href="http://www.ietf.org/rfc/rfc4120.txt">

     * http://www.ietf.org/rfc/rfc4120.txt</a>.

     *

     * @return byte array of encoded EncryptionKey object.

     * @exception Asn1Exception if an error occurs while decoding an ASN1

     * encoded data.

     * @exception IOException if an I/O error occurs while reading encoded

     * data.

     *

     */

    public synchronized byte[] asn1Encode() throws Asn1Exception, IOException {

        DerOutputStream bytes = new DerOutputStream();

        DerOutputStream temp = new DerOutputStream();

        temp.putInteger(keyType);

        bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true,

                                       (byte)0x00), temp);

        temp = new DerOutputStream();

        temp.putOctetString(keyValue);

        bytes.write(DerValue.createTag(DerValue.TAG_CONTEXT, true,

                                       (byte)0x01), temp);

        temp = new DerOutputStream();

        temp.write(DerValue.tag_Sequence, bytes);

        return temp.toByteArray();

    }

    public synchronized void destroy() {

        if (keyValue != null)

            for (int i = 0; i < keyValue.length; i++)

                keyValue[i] = 0;

    }

    /**

     * Parse (unmarshal) an Encryption key from a DER input stream.  This form

     * parsing might be used when expanding a value which is part of

     * a constructed sequence and uses explicitly tagged type.

     *

     * @param data the Der input stream value, which contains one or more

     * marshaled value.

     * @param explicitTag tag number.

     * @param optional indicate if this data field is optional

     * @exception Asn1Exception if an error occurs while decoding an ASN1

     * encoded data.

     * @exception IOException if an I/O error occurs while reading encoded

     * data.

     * @return an instance of EncryptionKey.

     *

     */

    public static EncryptionKey parse(DerInputStream data, byte

                                      explicitTag, boolean optional) throws

                                      Asn1Exception, IOException {

        if ((optional) && (((byte)data.peekByte() & (byte)0x1F) !=

                           explicitTag)) {

            return null;

        }

        DerValue der = data.getDerValue();

        if (explicitTag != (der.getTag() & (byte)0x1F))  {

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        } else {

            DerValue subDer = der.getData().getDerValue();

            return new EncryptionKey(subDer);

        }

    }

    /**

     * Writes key value in FCC format to a <code>CCacheOutputStream</code>.

     *

     * @param cos a <code>CCacheOutputStream</code> to be written to.

     * @exception IOException if an I/O exception occurs.

     * @see sun.security.krb5.internal.ccache.CCacheOutputStream

     *

     */

    public synchronized void writeKey(CCacheOutputStream cos)

        throws IOException {

        cos.write16(keyType);

        // we use KRB5_FCC_FVNO_3

        cos.write16(keyType); // key type is recorded twice.

        cos.write32(keyValue.length);

        for (int i = 0; i < keyValue.length; i++) {

            cos.write8(keyValue[i]);

        }

    }

    public String toString() {

        return new String("EncryptionKey: keyType=" + keyType

                          + " kvno=" + kvno

                          + " keyValue (hex dump)="

                          + (keyValue == null || keyValue.length == 0 ?

                        " Empty Key" : '\n' + Krb5.hexDumper.encode(keyValue)

                             + '\n'));

    }

    public static EncryptionKey findKey(int etype, EncryptionKey[] keys)

        throws KrbException {

        // check if encryption type is supported

        if (!EType.isSupported(etype)) {

            throw new KrbException("Encryption type " +

                EType.toString(etype) + " is not supported/enabled");

        }

        int ktype;

        for (int i = 0; i < keys.length; i++) {

            ktype = keys[i].getEType();

            if (EType.isSupported(ktype)) {

                if (etype == ktype) {

                    return keys[i];

                }

            }

        }

        // Key not found.

        // allow DES key to be used for the DES etypes

        if ((etype == EncryptedData.ETYPE_DES_CBC_CRC ||

            etype == EncryptedData.ETYPE_DES_CBC_MD5)) {

            for (int i = 0; i < keys.length; i++) {