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package net.jradius.tls;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import org.bouncycastle.asn1.DERBitString;
import org.bouncycastle.asn1.x509.KeyUsage;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.asn1.x509.X509CertificateStructure;
import org.bouncycastle.asn1.x509.X509Extension;
import org.bouncycastle.asn1.x509.X509Extensions;
import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.agreement.DHBasicAgreement;
import org.bouncycastle.crypto.generators.DHBasicKeyPairGenerator;
import org.bouncycastle.crypto.io.SignerInputStream;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.crypto.params.DHKeyGenerationParameters;
import org.bouncycastle.crypto.params.DHParameters;
import org.bouncycastle.crypto.params.DHPublicKeyParameters;
import org.bouncycastle.crypto.params.DSAPublicKeyParameters;
import org.bouncycastle.crypto.params.RSAKeyParameters;
import org.bouncycastle.crypto.util.PublicKeyFactory;
import org.bouncycastle.util.BigIntegers;
/**
* TLS 1.0 DH key exchange.
*/
class TlsDHKeyExchange implements TlsKeyExchange
{
private static final BigInteger ONE = BigInteger.valueOf(1);
private static final BigInteger TWO = BigInteger.valueOf(2);
private TlsProtocolHandler handler;
private CertificateVerifyer verifyer;
private short keyExchange;
private TlsSigner tlsSigner;
private AsymmetricKeyParameter serverPublicKey = null;
private DHPublicKeyParameters dhAgreeServerPublicKey = null;
private AsymmetricCipherKeyPair dhAgreeClientKeyPair = null;
TlsDHKeyExchange(TlsProtocolHandler handler, CertificateVerifyer verifyer, short keyExchange)
{
switch (keyExchange)
{
case TlsKeyExchange.KE_DH_RSA:
case TlsKeyExchange.KE_DH_DSS:
this.tlsSigner = null;
break;
case TlsKeyExchange.KE_DHE_RSA:
this.tlsSigner = new TlsRSASigner();
break;
case TlsKeyExchange.KE_DHE_DSS:
this.tlsSigner = new TlsDSSSigner();
break;
default:
throw new IllegalArgumentException("unsupported key exchange algorithm");
}
this.handler = handler;
this.verifyer = verifyer;
this.keyExchange = keyExchange;
}
public void skipServerCertificate() throws IOException
{
handler.failWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_unexpected_message);
}
public void processServerCertificate(Certificate serverCertificate) throws IOException
{
X509CertificateStructure x509Cert = serverCertificate.certs[0];
SubjectPublicKeyInfo keyInfo = x509Cert.getSubjectPublicKeyInfo();
try
{
this.serverPublicKey = PublicKeyFactory.createKey(keyInfo);
}
catch (RuntimeException e)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_unsupported_certificate);
}
// Sanity check the PublicKeyFactory
if (this.serverPublicKey.isPrivate())
{
handler.failWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_internal_error);
}
// TODO
/*
* Perform various checks per RFC2246 7.4.2: "Unless otherwise specified, the
* signing algorithm for the certificate must be the same as the algorithm for the
* certificate key."
*/
// TODO Should the 'instanceof' tests be replaces with stricter checks on keyInfo.getAlgorithmId()?
switch (this.keyExchange)
{
case TlsKeyExchange.KE_DH_DSS:
if (!(this.serverPublicKey instanceof DHPublicKeyParameters))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_certificate_unknown);
}
// TODO The algorithm used to sign the certificate should be DSS.
// x509Cert.getSignatureAlgorithm();
this.dhAgreeServerPublicKey = validateDHPublicKey((DHPublicKeyParameters)this.serverPublicKey);
break;
case TlsKeyExchange.KE_DH_RSA:
if (!(this.serverPublicKey instanceof DHPublicKeyParameters))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_certificate_unknown);
}
// TODO The algorithm used to sign the certificate should be RSA.
// x509Cert.getSignatureAlgorithm();
this.dhAgreeServerPublicKey = validateDHPublicKey((DHPublicKeyParameters)this.serverPublicKey);
break;
case TlsKeyExchange.KE_DHE_RSA:
if (!(this.serverPublicKey instanceof RSAKeyParameters))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_certificate_unknown);
}
validateKeyUsage(x509Cert, KeyUsage.digitalSignature);
break;
case TlsKeyExchange.KE_DHE_DSS:
if (!(this.serverPublicKey instanceof DSAPublicKeyParameters))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_certificate_unknown);
}
break;
default:
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_unsupported_certificate);
}
/*
* Verify them.
*/
if (!this.verifyer.isValid(serverCertificate.getCerts()))
{
handler.failWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_user_canceled);
}
}
public void skipServerKeyExchange() throws IOException
{
if (tlsSigner != null)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_unexpected_message);
}
}
public void processServerKeyExchange(InputStream is, SecurityParameters securityParameters)
throws IOException
{
if (tlsSigner == null)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_unexpected_message);
}
InputStream sigIn = is;
Signer signer = null;
if (tlsSigner != null)
{
signer = initSigner(tlsSigner, securityParameters);
sigIn = new SignerInputStream(is, signer);
}
byte[] pBytes = TlsUtils.readOpaque16(sigIn);
byte[] gBytes = TlsUtils.readOpaque16(sigIn);
byte[] YsBytes = TlsUtils.readOpaque16(sigIn);
if (signer != null)
{
byte[] sigByte = TlsUtils.readOpaque16(is);
if (!signer.verifySignature(sigByte))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_bad_certificate);
}
}
BigInteger p = new BigInteger(1, pBytes);
BigInteger g = new BigInteger(1, gBytes);
BigInteger Ys = new BigInteger(1, YsBytes);
this.dhAgreeServerPublicKey = validateDHPublicKey(new DHPublicKeyParameters(Ys,
new DHParameters(p, g)));
}
public byte[] generateClientKeyExchange() throws IOException
{
// TODO RFC 2246 7.4.72
/*
* If the client certificate already contains a suitable Diffie-Hellman key, then
* Yc is implicit and does not need to be sent again. In this case, the Client Key
* Exchange message will be sent, but will be empty.
*/
// return new byte[0];
/*
* Generate a keypair (using parameters from server key) and send the public value
* to the server.
*/
DHBasicKeyPairGenerator dhGen = new DHBasicKeyPairGenerator();
dhGen.init(new DHKeyGenerationParameters(handler.getRandom(),
dhAgreeServerPublicKey.getParameters()));
this.dhAgreeClientKeyPair = dhGen.generateKeyPair();
BigInteger Yc = ((DHPublicKeyParameters)dhAgreeClientKeyPair.getPublic()).getY();
return BigIntegers.asUnsignedByteArray(Yc);
}
public byte[] generatePremasterSecret() throws IOException
{
/*
* Diffie-Hellman basic key agreement
*/
DHBasicAgreement dhAgree = new DHBasicAgreement();
dhAgree.init(dhAgreeClientKeyPair.getPrivate());
BigInteger agreement = dhAgree.calculateAgreement(dhAgreeServerPublicKey);
return BigIntegers.asUnsignedByteArray(agreement);
}
private void validateKeyUsage(X509CertificateStructure c, int keyUsageBits) throws IOException
{
X509Extensions exts = c.getTBSCertificate().getExtensions();
if (exts != null)
{
X509Extension ext = exts.getExtension(X509Extensions.KeyUsage);
if (ext != null)
{
DERBitString ku = KeyUsage.getInstance(ext);
int bits = ku.getBytes()[0] & 0xff;
if ((bits & keyUsageBits) != keyUsageBits)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_certificate_unknown);
}
}
}
}
private Signer initSigner(TlsSigner tlsSigner, SecurityParameters securityParameters)
{
Signer signer = tlsSigner.createVerifyer(this.serverPublicKey);
signer.update(securityParameters.clientRandom, 0, securityParameters.clientRandom.length);
signer.update(securityParameters.serverRandom, 0, securityParameters.serverRandom.length);
return signer;
}
private DHPublicKeyParameters validateDHPublicKey(DHPublicKeyParameters key) throws IOException
{
BigInteger Y = key.getY();
DHParameters params = key.getParameters();
BigInteger p = params.getP();
BigInteger g = params.getG();
if (!p.isProbablePrime(2))
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_illegal_parameter);
}
if (g.compareTo(TWO) < 0 || g.compareTo(p.subtract(TWO)) > 0)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_illegal_parameter);
}
if (Y.compareTo(TWO) < 0 || Y.compareTo(p.subtract(ONE)) > 0)
{
handler.failWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_illegal_parameter);
}
// TODO See RFC 2631 for more discussion of Diffie-Hellman validation
return key;
}
}
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