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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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package sun.security.ssl;
import java.io.*;
import java.security.*;
import java.security.interfaces.*;
import javax.net.ssl.*;
import sun.security.krb5.EncryptionKey;
import sun.security.krb5.EncryptedData;
import sun.security.krb5.KrbException;
import sun.security.krb5.internal.crypto.KeyUsage;
/**
* This is the Kerberos premaster secret in the Kerberos client key
* exchange message (CLIENT --> SERVER); it holds the
* Kerberos-encrypted pre-master secret. The secret is encrypted using the
* Kerberos session key. The padding and size of the resulting message
* depends on the session key type, but the pre-master secret is
* always exactly 48 bytes.
*
*/
final class KerberosPreMasterSecret {
private ProtocolVersion protocolVersion; // preMaster [0,1]
private byte preMaster[]; // 48 bytes
private byte encrypted[];
/**
* Constructor used by client to generate premaster secret.
*
* Client randomly creates a pre-master secret and encrypts it
* using the Kerberos session key; only the server can decrypt
* it, using the session key available in the service ticket.
*
* @param protocolVersion used to set preMaster[0,1]
* @param generator random number generator for generating premaster secret
* @param sessionKey Kerberos session key for encrypting premaster secret
*/
KerberosPreMasterSecret(ProtocolVersion protocolVersion,
SecureRandom generator, EncryptionKey sessionKey) throws IOException {
if (sessionKey.getEType() ==
EncryptedData.ETYPE_DES3_CBC_HMAC_SHA1_KD) {
throw new IOException(
"session keys with des3-cbc-hmac-sha1-kd encryption type " +
"are not supported for TLS Kerberos cipher suites");
}
this.protocolVersion = protocolVersion;
preMaster = generatePreMaster(generator, protocolVersion);
// Encrypt premaster secret
try {
EncryptedData eData = new EncryptedData(sessionKey, preMaster,
KeyUsage.KU_UNKNOWN);
encrypted = eData.getBytes(); // not ASN.1 encoded.
} catch (KrbException e) {
throw (SSLKeyException)new SSLKeyException
("Kerberos premaster secret error").initCause(e);
}
}
/*
* Constructor used by server to decrypt encrypted premaster secret.
* The protocol version in preMaster[0,1] must match either currentVersion
* or clientVersion, otherwise, the premaster secret is set to
* a random one to foil possible attack.
*
* @param currentVersion version of protocol being used
* @param clientVersion version requested by client
* @param generator random number generator used to generate
* bogus premaster secret if premaster secret verification fails
* @param input input stream from which to read the encrypted
* premaster secret
* @param sessionKey Kerberos session key to be used for decryption
*/
KerberosPreMasterSecret(ProtocolVersion currentVersion,
ProtocolVersion clientVersion,
SecureRandom generator, HandshakeInStream input,
EncryptionKey sessionKey) throws IOException {
// Extract encrypted premaster secret from message
encrypted = input.getBytes16();
if (HandshakeMessage.debug != null && Debug.isOn("handshake")) {
if (encrypted != null) {
Debug.println(System.out,
"encrypted premaster secret", encrypted);
}
}
if (sessionKey.getEType() ==
EncryptedData.ETYPE_DES3_CBC_HMAC_SHA1_KD) {
throw new IOException(
"session keys with des3-cbc-hmac-sha1-kd encryption type " +
"are not supported for TLS Kerberos cipher suites");
}
// Decrypt premaster secret
try {
EncryptedData data = new EncryptedData(sessionKey.getEType(),
null /* optional kvno */, encrypted);
byte[] temp = data.decrypt(sessionKey, KeyUsage.KU_UNKNOWN);
if (HandshakeMessage.debug != null && Debug.isOn("handshake")) {
if (encrypted != null) {
Debug.println(System.out,
"decrypted premaster secret", temp);
}
}
// Reset data stream after decryption, remove redundant bytes
preMaster = data.reset(temp, false);
protocolVersion = ProtocolVersion.valueOf(preMaster[0],
preMaster[1]);
if (HandshakeMessage.debug != null && Debug.isOn("handshake")) {
System.out.println("Kerberos PreMasterSecret version: "
+ protocolVersion);
}
} catch (Exception e) {
// catch exception & process below
preMaster = null;
protocolVersion = currentVersion;
}
// check if the premaster secret version is ok
// the specification says that it must be the maximum version supported
// by the client from its ClientHello message. However, many
// implementations send the negotiated version, so accept both
// NOTE that we may be comparing two unsupported version numbers in
// the second case, which is why we cannot use object references
// equality in this special case
boolean versionMismatch = (protocolVersion != currentVersion) &&
(protocolVersion.v != clientVersion.v);
/*
* Bogus decrypted ClientKeyExchange? If so, conjure a
* a random preMaster secret that will fail later during
* Finished message processing. This is a countermeasure against
* the "interactive RSA PKCS#1 encryption envelop attack" reported
* in June 1998. Preserving the executation path will
* mitigate timing attacks and force consistent error handling
* that will prevent an attacking client from differentiating
* different kinds of decrypted ClientKeyExchange bogosities.
*/
if ((preMaster == null) || (preMaster.length != 48)
|| versionMismatch) {
if (HandshakeMessage.debug != null && Debug.isOn("handshake")) {
System.out.println("Kerberos PreMasterSecret error, "
+ "generating random secret");
if (preMaster != null) {
Debug.println(System.out, "Invalid secret", preMaster);
}
}
preMaster = generatePreMaster(generator, currentVersion);
protocolVersion = currentVersion;
}
}
/*
* Used by server to generate premaster secret in case of
* problem decoding ticket.
*
* @param protocolVersion used for preMaster[0,1]
* @param generator random number generator to use for generating secret.
*/
KerberosPreMasterSecret(ProtocolVersion protocolVersion,
SecureRandom generator) {
this.protocolVersion = protocolVersion;
preMaster = generatePreMaster(generator, protocolVersion);
}
private static byte[] generatePreMaster(SecureRandom rand,
ProtocolVersion ver) {
byte[] pm = new byte[48];
rand.nextBytes(pm);
pm[0] = ver.major;
pm[1] = ver.minor;
return pm;
}
// Clone not needed; package internal use only
byte[] getUnencrypted() {
return preMaster;
}
// Clone not needed; package internal use only
byte[] getEncrypted() {
return encrypted;
}
}