From faec826c0d976301b075500b079241bc88619658 Mon Sep 17 00:00:00 2001
From: Peter Palfrader <peter@palfrader.org>
Date: Wed, 15 Oct 2003 16:41:45 +0000
Subject: Verify remote peer cert during MMTP handshake

---
 src/org/noreply/fancydress/type3/mmtp/MMTP.java    |  3 +-
 .../fancydress/type3/mmtp/MMTPTrustManager.java    | 59 +++++++++++++++-------
 2 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/src/org/noreply/fancydress/type3/mmtp/MMTP.java b/src/org/noreply/fancydress/type3/mmtp/MMTP.java
index 1d03eed..bc19e8e 100644
--- a/src/org/noreply/fancydress/type3/mmtp/MMTP.java
+++ b/src/org/noreply/fancydress/type3/mmtp/MMTP.java
@@ -20,7 +20,7 @@ public class MMTP {
 		byte[] ackExpected = Util.concat( Util.toOctets("RECEIVED\r\n"),
 				                  CryptoPrimitives.hash(packet.asOctets(), Util.toOctets("RECEIVED")));
 		byte[] ackRead = new byte[30];
-		MMTPTrustManager trustManager = new MMTPTrustManager();
+		MMTPTrustManager trustManager = new MMTPTrustManager(packet.getRoute().getKeyID());
 		TrustManager[] trustManagers = { trustManager };
 		SSLContext context = SSLContext.getInstance("TLS");
 		context.init(null, trustManagers, null);
@@ -58,7 +58,6 @@ public class MMTP {
 		} else {
 			System.out.println("Got ACK");
 		};
-		System.out.println(Util.asHex(packet.getRoute().getKeyID()));
 		in.close();
 		out.close();
 		socket.close();
diff --git a/src/org/noreply/fancydress/type3/mmtp/MMTPTrustManager.java b/src/org/noreply/fancydress/type3/mmtp/MMTPTrustManager.java
index e39f5f9..4748a84 100644
--- a/src/org/noreply/fancydress/type3/mmtp/MMTPTrustManager.java
+++ b/src/org/noreply/fancydress/type3/mmtp/MMTPTrustManager.java
@@ -5,13 +5,28 @@ import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;
 import javax.net.ssl.X509TrustManager;
 import java.security.AlgorithmParameters;
-import java.math.*;
+import java.security.NoSuchAlgorithmException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchProviderException;
+import java.security.SignatureException;
+import java.math.BigInteger;
 import org.bouncycastle.util.encoders.Base64;
 import org.noreply.fancydress.misc.*;
 import org.noreply.fancydress.crypto.*;
 
 public class MMTPTrustManager implements X509TrustManager {
-	public MMTPTrustManager() {
+	/**
+	 * Hash of the expected identity key.
+	 */
+	private byte[] identity;
+
+	/**
+	 * Create a new MMTPTrustManager instance.
+	 *
+	 * @param keyid fingerprint (== keyid, == hash of the key) of the identity key.
+	 */
+	public MMTPTrustManager(byte[] identity) {
+		this.identity = identity;
 	}
 
 	/**
@@ -55,20 +70,31 @@ public class MMTPTrustManager implements X509TrustManager {
 	public void checkServerTrusted(X509Certificate[] chain, String authType)
 		throws CertificateException
 	{
-		System.out.println("call to checkServerTrusted()\n");
-		System.out.println("certs: " + chain.length);
-		for (int i=0; i<chain.length; i++) {
-			System.out.println("cert "+i+"\n" + chain[i]);
-			System.out.println("alg name: " + chain[i].getSigAlgName() );
-			java.security.interfaces.RSAPublicKey pk = (java.security.interfaces.RSAPublicKey) chain[i].getPublicKey();
-			BigInteger modulus = pk.getModulus();
-			BigInteger exp = pk.getPublicExponent();
-			RSAPublicKey rsa = new RSAPublicKey(modulus,exp);
-			System.out.println("fpr: " + Util.asHex( rsa.getFingerprint() ));
-			//System.out.println("fpr: " + chain[i].getSigAlgParams() == null ? "null" : Util.asHex( CryptoPrimitives.hash( chain[i].getSigAlgParams() )));
-		}
-		System.out.println("authtype: " + authType);
+		/* Make sure we got two keys */
+		if (chain.length != 2)
+			throw new CertificateException("Did not get excatly 2 certificates in cert chain.");
 
+		/* Verify, that the first cert is signed by the second cert */
+		java.security.interfaces.RSAPublicKey identityCertKey = (java.security.interfaces.RSAPublicKey) chain[1].getPublicKey();
+		try {
+			chain[0].verify(identityCertKey);
+		} catch (NoSuchAlgorithmException e) {
+			throw new CertificateException("Could not verify chain.  Caused by NoSuchAlgorithmException,");
+		} catch (InvalidKeyException e) {
+			throw new CertificateException("Could not verify chain.  Caused by InvalidKeyException,");
+		} catch (NoSuchProviderException e) {
+			throw new CertificateException("Could not verify chain.  Caused by NoSuchProviderException,");
+		} catch (SignatureException e) {
+			throw new CertificateException("Could not verify chain.  Caused by SignatureException,");
+		};
+
+		/* Verify, that the second cert is the identity key */
+		BigInteger modulus = identityCertKey.getModulus();
+		BigInteger exp = identityCertKey.getPublicExponent();
+		RSAPublicKey rsa = new RSAPublicKey(modulus,exp);
+		byte[] fpr = rsa.getFingerprint();
+		if (!Util.equal(identity, fpr))
+			throw new CertificateException("Identity key's fingerprint does not match expected value.");
 	}
 
 	/**
@@ -79,7 +105,6 @@ public class MMTPTrustManager implements X509TrustManager {
 	 *         certificates.
 	 */
 	public X509Certificate[] getAcceptedIssuers() {
-		System.out.println("call to getAcceptedIssuers()\n");
-		return new X509Certificate[0];
+		throw new Error("Not needed\n");
 	}
 }
-- 
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