1 files changed, 113 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/tls/TlsDHEKeyExchange.java b/core/src/main/java/org/bouncycastle/crypto/tls/TlsDHEKeyExchange.java
new file mode 100644
index 00000000..57376592
--- /dev/null
+++ b/core/src/main/java/org/bouncycastle/crypto/tls/TlsDHEKeyExchange.java
@@ -0,0 +1,113 @@
+package org.bouncycastle.crypto.tls;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.math.BigInteger;
+import java.util.Vector;
+
+import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.Signer;
+import org.bouncycastle.crypto.generators.DHKeyPairGenerator;
+import org.bouncycastle.crypto.io.SignerInputStream;
+import org.bouncycastle.crypto.params.DHKeyGenerationParameters;
+import org.bouncycastle.crypto.params.DHParameters;
+import org.bouncycastle.crypto.params.DHPublicKeyParameters;
+
+public class TlsDHEKeyExchange
+    extends TlsDHKeyExchange
+{
+
+    protected TlsSignerCredentials serverCredentials = null;
+
+    public TlsDHEKeyExchange(int keyExchange, Vector supportedSignatureAlgorithms, DHParameters dhParameters)
+    {
+        super(keyExchange, supportedSignatureAlgorithms, dhParameters);
+    }
+
+    public void processServerCredentials(TlsCredentials serverCredentials)
+        throws IOException
+    {
+
+        if (!(serverCredentials instanceof TlsSignerCredentials))
+        {
+            throw new TlsFatalAlert(AlertDescription.internal_error);
+        }
+
+        processServerCertificate(serverCredentials.getCertificate());
+
+        this.serverCredentials = (TlsSignerCredentials)serverCredentials;
+    }
+
+    public byte[] generateServerKeyExchange()
+        throws IOException
+    {
+
+        if (this.dhParameters == null)
+        {
+            throw new TlsFatalAlert(AlertDescription.internal_error);
+        }
+
+        ByteArrayOutputStream buf = new ByteArrayOutputStream();
+
+        DHKeyPairGenerator kpg = new DHKeyPairGenerator();
+        kpg.init(new DHKeyGenerationParameters(context.getSecureRandom(), this.dhParameters));
+        AsymmetricCipherKeyPair kp = kpg.generateKeyPair();
+
+        BigInteger Ys = ((DHPublicKeyParameters)kp.getPublic()).getY();
+
+        TlsDHUtils.writeDHParameter(dhParameters.getP(), buf);
+        TlsDHUtils.writeDHParameter(dhParameters.getG(), buf);
+        TlsDHUtils.writeDHParameter(Ys, buf);
+
+        byte[] digestInput = buf.toByteArray();
+
+        Digest d = new CombinedHash();
+        SecurityParameters securityParameters = context.getSecurityParameters();
+        d.update(securityParameters.clientRandom, 0, securityParameters.clientRandom.length);
+        d.update(securityParameters.serverRandom, 0, securityParameters.serverRandom.length);
+        d.update(digestInput, 0, digestInput.length);
+
+        byte[] hash = new byte[d.getDigestSize()];
+        d.doFinal(hash, 0);
+
+        byte[] sigBytes = serverCredentials.generateCertificateSignature(hash);
+        /*
+         * TODO RFC 5246 4.7. digitally-signed element needs SignatureAndHashAlgorithm prepended from TLS 1.2
+         */
+        TlsUtils.writeOpaque16(sigBytes, buf);
+
+        return buf.toByteArray();
+    }
+
+    public void processServerKeyExchange(InputStream input)
+        throws IOException
+    {
+
+        SecurityParameters securityParameters = context.getSecurityParameters();
+
+        Signer signer = initVerifyer(tlsSigner, securityParameters);
+        InputStream sigIn = new SignerInputStream(input, signer);
+
+        BigInteger p = TlsDHUtils.readDHParameter(sigIn);
+        BigInteger g = TlsDHUtils.readDHParameter(sigIn);
+        BigInteger Ys = TlsDHUtils.readDHParameter(sigIn);
+
+        byte[] sigBytes = TlsUtils.readOpaque16(input);
+        if (!signer.verifySignature(sigBytes))
+        {
+            throw new TlsFatalAlert(AlertDescription.decrypt_error);
+        }
+
+        this.dhAgreeServerPublicKey = validateDHPublicKey(new DHPublicKeyParameters(Ys, new DHParameters(p, g)));
+    }
+
+    protected Signer initVerifyer(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;
+    }
+}