Fixed bug #2146 => A calculation is now fine. Next step: fix M1

calculation, since right now (using tests) response() method is not
doing OK.

Added new SRPSession modifying response() method from JBoss SRP
implementation.

Added hosts-for-android-emulator. Use with the following commands to be
able to test on api.lvh.me:
adb shell mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system
adb push ~/workspace/leap_android/hosts-for-android-emulator 
/system/etc/hosts

4 files changed, 249 insertions, 60 deletions

diff --git a/hosts-for-android-emulator b/hosts-for-android-emulator
new file mode 100644
index 00000000..b10103ef
--- /dev/null
+++ b/hosts-for-android-emulator
@@ -0,0 +1,9 @@
+127.0.0.1	localhost
+10.0.2.2	api.lvh.me
+
+# The following lines are desirable for IPv6 capable hosts
+::1     ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
diff --git a/src/se/leap/leapclient/LeapHttpClient.java b/src/se/leap/leapclient/LeapHttpClient.java
index 9e1a541b..fd6db745 100644
--- a/src/se/leap/leapclient/LeapHttpClient.java
+++ b/src/se/leap/leapclient/LeapHttpClient.java
@@ -15,6 +15,8 @@ import android.content.Context;
 
 public class LeapHttpClient extends DefaultHttpClient {
 	final Context context;
+	
+	private static LeapHttpClient client;
 
 	  public LeapHttpClient(Context context) {
 	      this.context = context;
@@ -55,4 +57,10 @@ public class LeapHttpClient extends DefaultHttpClient {
 	          throw new AssertionError(e);
 	      }
 	  }
+	  
+	  public static LeapHttpClient getInstance(Context context) {
+		  if(client == null)
+			  client = new LeapHttpClient(context);
+		  return client;
+	  }
 }
diff --git a/src/se/leap/leapclient/LeapSRPSession.java b/src/se/leap/leapclient/LeapSRPSession.java
new file mode 100644
index 00000000..1d1f0c9d
--- /dev/null
+++ b/src/se/leap/leapclient/LeapSRPSession.java
@@ -0,0 +1,193 @@
+package se.leap.leapclient;
+
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+
+import org.jboss.security.Util;
+import org.jboss.security.srp.SRPClientSession;
+import org.jboss.security.srp.SRPParameters;
+import org.jboss.security.srp.SRPPermission;
+
+public class LeapSRPSession {
+	
+	private SRPParameters params;
+	   private BigInteger N;
+	   private BigInteger g;
+	   private BigInteger x;
+	   private BigInteger v;
+	   private byte[] s;
+	   private BigInteger a;
+	   private BigInteger A;
+	   private byte[] K;
+	   /** The M1 = H(H(N) xor H(g) | H(U) | s | A | B | K) hash */
+	   private MessageDigest clientHash;
+	   /** The M2 = H(A | M | K) hash */
+	   private MessageDigest serverHash;
+	   
+	   private static int A_LEN;
+
+	   /** Creates a new SRP server session object from the username, password
+	    verifier,
+	    @param username, the user ID
+	    @param password, the user clear text password
+	    @param params, the SRP parameters for the session
+	    */
+	   public LeapSRPSession(String username, char[] password, SRPParameters params)
+	   {
+	      this(username, password, params, null);
+	   }
+
+	   /** Creates a new SRP server session object from the username, password
+	    verifier,
+	    @param username, the user ID
+	    @param password, the user clear text password
+	    @param params, the SRP parameters for the session
+	    @param abytes, the random exponent used in the A public key. This must be
+	      8 bytes in length.
+	    */
+	   public LeapSRPSession(String username, char[] password, SRPParameters params,
+	      byte[] abytes)
+	   {
+	      try
+	      {
+	         // Initialize the secure random number and message digests
+	         Util.init();
+	      }
+	      catch(NoSuchAlgorithmException e)
+	      {
+	      }
+	      this.params = params;
+	      this.g = new BigInteger(1, params.g);
+	      this.N = new BigInteger(1, params.N);
+	      if( abytes != null )
+	      {
+	    	  A_LEN = 8*abytes.length;
+	    	  /* TODO Why did they put this condition?
+	         if( 8*abytes.length != A_LEN )
+	            throw new IllegalArgumentException("The abytes param must be "
+	               +(A_LEN/8)+" in length, abytes.length="+abytes.length);
+	               */
+	         this.a = new BigInteger(abytes);
+	      }
+
+	      // Calculate x = H(s | H(U | ':' | password))
+	      byte[] xb = Util.calculatePasswordHash(username, password, params.s);
+	      this.x = new BigInteger(1, xb);
+	      this.v = g.modPow(x, N);  // g^x % N
+	      
+	      serverHash = Util.newDigest();
+	      clientHash = Util.newDigest();
+	      // H(N)
+	      byte[] hn = Util.newDigest().digest(params.N);
+	      // H(g)
+	      byte[] hg = Util.newDigest().digest(params.g);
+	      // clientHash = H(N) xor H(g)
+	      byte[] hxg = Util.xor(hn, hg, 20);
+	      clientHash.update(hxg);
+	      // clientHash = H(N) xor H(g) | H(U)
+	      clientHash.update(Util.newDigest().digest(username.getBytes()));
+	      // clientHash = H(N) xor H(g) | H(U) | s
+	      clientHash.update(params.s);
+	      K = null;
+	   }
+	   
+	   /**
+	    * @returns The exponential residue (parameter A) to be sent to the server.
+	    */
+	   public byte[] exponential()
+	   {
+	      byte[] Abytes = null;
+	      if(A == null)
+	      {
+	         /* If the random component of A has not been specified use a random
+	         number */
+	         if( a == null )
+	         {
+	            BigInteger one = BigInteger.ONE;
+	            do
+	            {
+	               a = new BigInteger(A_LEN, Util.getPRNG());
+	            } while(a.compareTo(one) <= 0);
+	         }
+	         A = g.modPow(a, N);
+	         Abytes = Util.trim(A.toByteArray());
+	         // clientHash = H(N) xor H(g) | H(U) | A
+	         clientHash.update(Abytes);
+	         // serverHash = A
+	         serverHash.update(Abytes);
+	      }
+	      return Abytes;
+	   }
+	   
+		public byte[] response(byte[] Bbytes) throws NoSuchAlgorithmException {
+			// clientHash = H(N) xor H(g) | H(U) | s | A | B
+		      clientHash.update(Bbytes);
+		      
+		      /*
+		      var B = new BigInteger(ephemeral, 16);
+		      var Bstr = ephemeral;
+		      // u = H(A,B)
+		      var u = new BigInteger(SHA256(hex2a(Astr + Bstr)), 16);
+		      // x = H(s, H(I:p))
+		      var x = this.calcX(salt);
+		      //S = (B - kg^x) ^ (a + ux)
+		      var kgx = k.multiply(g.modPow(x, N));
+		      var aux = a.add(u.multiply(x));
+		      S = B.subtract(kgx).modPow(aux, N);
+		      K = SHA256(hex2a(S.toString(16)));
+		      */
+		      byte[] hA = Util.newDigest().digest(A.toByteArray());
+		      MessageDigest u_digest = Util.newDigest();
+		      u_digest.update(A.toByteArray());
+		      u_digest.update(Bbytes);
+		      clientHash.update(u_digest.digest());
+		      byte[] ub = new BigInteger(clientHash.digest()).toByteArray();
+		      // Calculate S = (B - g^x) ^ (a + u * x) % N
+		      BigInteger B = new BigInteger(1, Bbytes);
+		      if( B.compareTo(v) < 0 )
+		         B = B.add(N);
+		      BigInteger u = new BigInteger(1, ub);
+		      BigInteger B_v = B.subtract(v);
+		      BigInteger a_ux = a.add(u.multiply(x));
+		      BigInteger S = B_v.modPow(a_ux, N);
+		      // K = SessionHash(S)
+		      MessageDigest sessionDigest = MessageDigest.getInstance(params.hashAlgorithm);
+		      K = sessionDigest.digest(S.toByteArray());
+		      // clientHash = H(N) xor H(g) | H(U) | A | B | K
+		      clientHash.update(K);
+		      byte[] M1 = clientHash.digest();
+		      return M1;
+		}
+	   
+	   
+	   /**
+	    * @param M2 The server's response to the client's challenge
+	    * @returns True if and only if the server's response was correct.
+	    */
+	   public boolean verify(byte[] M2)
+	   {
+	      // M2 = H(A | M1 | K)
+	      byte[] myM2 = serverHash.digest();
+	      boolean valid = Arrays.equals(M2, myM2);
+	      return valid;
+	   }
+	   
+	   /** Returns the negotiated session K, K = SHA_Interleave(S)
+	    @return the private session K byte[]
+	    @throws SecurityException - if the current thread does not have an
+	    getSessionKey SRPPermission.
+	    */
+	   public byte[] getSessionKey() throws SecurityException
+	   {
+	      SecurityManager sm = System.getSecurityManager();
+	      if( sm != null )
+	      {
+	         SRPPermission p = new SRPPermission("getSessionKey");
+	         sm.checkPermission(p);
+	      }
+	      return K;
+	   }
+
+}
diff --git a/src/se/leap/leapclient/ProviderAPI.java b/src/se/leap/leapclient/ProviderAPI.java
index b8d6a765..ea1410ad 100644
--- a/src/se/leap/leapclient/ProviderAPI.java
+++ b/src/se/leap/leapclient/ProviderAPI.java
@@ -3,7 +3,6 @@ package se.leap.leapclient;
 import java.io.IOException;
 import java.math.BigInteger;
 import java.security.NoSuchAlgorithmException;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Scanner;
 
@@ -13,15 +12,16 @@ import org.apache.http.client.ClientProtocolException;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.client.methods.HttpPut;
+import org.apache.http.client.protocol.ClientContext;
 import org.apache.http.cookie.Cookie;
 import org.apache.http.impl.client.DefaultHttpClient;
+import org.apache.http.protocol.BasicHttpContext;
+import org.apache.http.protocol.HttpContext;
+import org.jboss.security.srp.SRPClientSession;
+import org.jboss.security.srp.SRPParameters;
 import org.json.JSONException;
 import org.json.JSONObject;
 
-import com.jordanzimmerman.SRPClientSession;
-import com.jordanzimmerman.SRPConstants;
-import com.jordanzimmerman.SRPFactory;
-
 import se.leap.leapclient.ProviderListContent.ProviderItem;
 
 import android.app.IntentService;
@@ -121,22 +121,31 @@ public class ProviderAPI extends IntentService {
 		String username = (String) task.get(ConfigHelper.username_key);
 		String password = (String) task.get(ConfigHelper.password_key);
 		String authentication_server = (String) task.get(ConfigHelper.srp_server_url_key);
+		
+		String salt = "abcd";
 
-		SRPConstants constants = new SRPConstants(new BigInteger(ConfigHelper.NG_1024, 16), ConfigHelper.g);
-		SRPFactory 			factory = SRPFactory.getInstance(constants);
-		SRPClientSession session = factory.newClientSession(password.getBytes());
-		session.setSalt_s(new BigInteger("1"));
-		byte[] A = session.getPublicKey_A().toString(16).getBytes();
+		SRPParameters params = new SRPParameters(new BigInteger(ConfigHelper.NG_1024, 16).toByteArray(), new BigInteger("2").toByteArray(), new BigInteger(salt, 16).toByteArray(), "SHA-256");
+		//SRPClientSession client = new SRPClientSession(username, password.toCharArray(), params);
+		LeapSRPSession client = new LeapSRPSession(username, password.toCharArray(), params);
+		byte[] A = client.exponential();
 		try {
-			JSONObject saltAndB = sendAToSRPServer(authentication_server, username, getHexString(A));
-			String B = saltAndB.getString("B");
-			String salt = saltAndB.getString("salt");
-			session.setSalt_s(new BigInteger(salt, 16));
-			session.setServerPublicKey_B(new BigInteger(B, 16));
-			byte[] M1 = session.getEvidenceValue_M1().toString(16).getBytes();
-			byte[] M2 = sendM1ToSRPServer(authentication_server, username, M1);
-			session.validateServerEvidenceValue_M2(new BigInteger(getHexString(M2), 16));
-			return true;
+			JSONObject saltAndB = sendAToSRPServer(authentication_server, username, new BigInteger(A).toString(16));
+			if(saltAndB.length() > 0) {
+				byte[] B = saltAndB.getString("B").getBytes();
+				salt = saltAndB.getString("salt");
+				params = new SRPParameters(new BigInteger(ConfigHelper.NG_1024, 16).toByteArray(), new BigInteger("2").toByteArray(), new BigInteger(salt, 16).toByteArray(), "SHA-256");
+				//client = new SRPClientSession(username, password.toCharArray(), params);
+				client = new LeapSRPSession(username, password.toCharArray(), params);
+				A = client.exponential();
+				saltAndB = sendAToSRPServer(authentication_server, username, new BigInteger(A).toString(16));
+				String Bhex = saltAndB.getString("B");
+				byte[] M1 = client.response(new BigInteger(Bhex, 16).toByteArray());
+				byte[] M2 = sendM1ToSRPServer(authentication_server, username, M1);
+				if( client.verify(M2) == false )
+					throw new SecurityException("Failed to validate server reply");
+				return true;
+			}
+			else return false;
 		} catch (ClientProtocolException e1) {
 			// TODO Auto-generated catch block
 			e1.printStackTrace();
@@ -149,25 +158,15 @@ public class ProviderAPI extends IntentService {
 			// TODO Auto-generated catch block
 			e1.printStackTrace();
 			return false;
+		} catch (NoSuchAlgorithmException e) {
+			// TODO Auto-generated catch block
+			e.printStackTrace();
+			return false;
 		}
 	}
-	
-	public static String getHexString(byte[] b) {
-		  String result = "";
-		  StringBuffer sb = new StringBuffer();
-			for (byte tmp : b) {
-				sb.append(Integer.toHexString((int) (tmp & 0xff)));
-			}
-			return sb.toString();
-//		  for (int i=0; i < b.length; i++) {
-//		    result +=
-//		          Integer.toString( ( b[i] & 0xff ) + 0x100, 16).substring( 1 );
-//		  }
-//		  return result;
-		}
 
 	private JSONObject sendAToSRPServer(String server_url, String username, String clientA) throws ClientProtocolException, IOException, JSONException {
-		DefaultHttpClient client = new LeapHttpClient(getApplicationContext());
+		DefaultHttpClient client = LeapHttpClient.getInstance(getApplicationContext());
 		String parameter_chain = "A" + "=" + clientA + "&" + "login" + "=" + username;
 		HttpPost post = new HttpPost(server_url + "/sessions.json" + "?" + parameter_chain);
 	
@@ -185,31 +184,14 @@ public class ProviderAPI extends IntentService {
 		return json_response;
 	}
 
-	private byte[] sendAToSRPServer(String server_url, String username, byte[] clientA) throws ClientProtocolException, IOException, JSONException {
-		DefaultHttpClient client = new LeapHttpClient(getApplicationContext());
-		String parameter_chain = "A" + "=" + getHexString(clientA) + "&" + "login" + "=" + username;
-		HttpPost post = new HttpPost(server_url + "/sessions.json" + "?" + parameter_chain);
-	
-		HttpResponse getResponse = client.execute(post);
-		HttpEntity responseEntity = getResponse.getEntity();
-		String plain_response = new Scanner(responseEntity.getContent()).useDelimiter("\\A").next();
-		JSONObject json_response = new JSONObject(plain_response);
-		if(!json_response.isNull("errors") || json_response.has("errors")) {
-			return new byte[0];
-		}
-		List<Cookie> cookies = client.getCookieStore().getCookies();
-		if(!cookies.isEmpty()) {
-			String session_id = cookies.get(0).getValue();
-		}
-		return json_response.getString("B").getBytes();
-	}
-
 	private byte[] sendM1ToSRPServer(String server_url, String username, byte[] m1) throws ClientProtocolException, IOException, JSONException {
-		DefaultHttpClient client = new LeapHttpClient(getApplicationContext());
-		String parameter_chain = "client_auth" + "=" + getHexString(m1);
+		DefaultHttpClient client = LeapHttpClient.getInstance(getApplicationContext());
+		String parameter_chain = "client_auth" + "=" + new BigInteger(m1).toString(16);
 		HttpPut put = new HttpPut(server_url + "/sessions/" + username +".json" + "?" + parameter_chain);
+		HttpContext localContext = new BasicHttpContext();
+		localContext.setAttribute(ClientContext.COOKIE_STORE, client.getCookieStore());
 		
-		HttpResponse getResponse = client.execute(put);
+		HttpResponse getResponse = client.execute(put, localContext);
 		HttpEntity responseEntity = getResponse.getEntity();
 		String plain_response = new Scanner(responseEntity.getContent()).useDelimiter("\\A").next();
 		JSONObject json_response = new JSONObject(plain_response);
@@ -217,9 +199,6 @@ public class ProviderAPI extends IntentService {
 			return new byte[0];
 		}
 		
-		List<Cookie> cookies = client.getCookieStore().getCookies();
-		String session_id = cookies.get(0).getValue();
-		
 		return json_response.getString("M2").getBytes();
 	}
 
@@ -231,7 +210,7 @@ public class ProviderAPI extends IntentService {
 		
 		String json_file_content = "";
 		
-		DefaultHttpClient client = new LeapHttpClient(getApplicationContext());
+		DefaultHttpClient client = LeapHttpClient.getInstance(getApplicationContext());
 		HttpGet get = new HttpGet(string_url);
 		// Execute the GET call and obtain the response
 		HttpResponse getResponse = client.execute(get);