refactor encryption/decryption to Render class

app/src/main/java/org/surfsite/android/secretshare/GenerateFragment.java

@@ -1,15 +1,11 @@
 package org.surfsite.android.secretshare;
 
 import android.app.Activity;
-import android.app.AlertDialog;
 import android.app.Fragment;
-import android.content.DialogInterface;
 import android.graphics.Bitmap;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Bundle;
-import android.support.v4.print.PrintHelper;
-import android.util.Base64;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -19,9 +15,8 @@ import android.widget.TextView;
 import com.tiemens.secretshare.engine.SecretShare;
 import com.tiemens.secretshare.engine.SecretShare.ShareInfo;
 
-import java.io.UnsupportedEncodingException;
 import java.math.BigInteger;
-import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.List;
 
 
@@ -66,17 +61,6 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 		return fragment;
 	}
 
-	static BigInteger stringToBigInteger(String in) {
-		BigInteger bigint;
-		try {
-			bigint = new BigInteger(in.getBytes("UTF-8"));
-		} catch (UnsupportedEncodingException ex) {
-			ex.printStackTrace();
-			bigint = BigInteger.ZERO;
-		}
-		return bigint;
-	}
-
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -163,6 +147,8 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 
 	private class GenerateSharesTask extends AsyncTask<Void, Void, Void> {
 		private final Activity activity;
+		SecretShare.PublicInfo pi = null;
+		ShareInfo si[];
 		private TextView tv;
 		private List<SecretShare.ShareInfo> pieces;
 		private int n;
@@ -179,6 +165,7 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 			this.n = n;
 			this.k = k;
 			this.cleartext = cleartext;
+			si = new ShareInfo[n];
 			this.tv.setText("Generating shared secrets for " + cleartext.length()
 					+ " chars. Please Wait. This can take a long time.");
 		}
@@ -189,7 +176,7 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 
 		@Override
 		protected Void doInBackground(Void... params) {
-			final BigInteger secretInteger = stringToBigInteger(cleartext);
+			final BigInteger secretInteger = Renderer.stringToBigInteger(cleartext);
 			final BigInteger modulus;
 
 			modulus = SecretShare.createAppropriateModulusForSecret(secretInteger);
@@ -211,32 +198,20 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 			for (int i = 0; i < out.length; i++) {
 				final ShareInfo piece = pieces.get(i);
 
-				byte[] bmodulus = publicInfo.getPrimeModulus().toByteArray();
+				final String data = Renderer.encodeShareInfo(piece);
-				byte[] bshare = piece.getShare().toByteArray();
-				int blen = 4 + 4 + 4 + 4 + 4 + bmodulus.length + bshare.length;
-				final ByteBuffer bencoded = ByteBuffer.allocate(blen);
-				bencoded.putInt(n).putInt(k).putInt(piece.getX());
-				bencoded.putInt(bmodulus.length).put(bmodulus);
-				bencoded.putInt(bshare.length).put(bshare);
 
-				tv.append("Length: " + blen + "\n");
+				out[i] = "ssss-android:" + piece.getX() + "/" + k + ":" + n + "-"
-
+						+ publicInfo.getDescription()
-				out[i] = n + ":" + k + ":" + piece.getX() + ":"
 						+ publicInfo.getPrimeModulus() + ":" + piece.getShare();
 
-				tv.append("OutLen: " + out[i].length() + "\n");
 				tv.append(out[i] + "\n");
-				tv.append(bencoded + "\n0x");
+				tv.append("B64Len: " + data.length() + "\n");
-				for (byte b : bencoded.array()) {
+				tv.append(data + "\n");
-					tv.append(String.format("%x", b));
+				if (pi == null)
-				}
+					pi = Renderer.decodePublicInfo(data);
-				tv.append("\n");
-				String bencoded64 = Base64.encodeToString(bencoded.array(), Base64.DEFAULT);
-				tv.append("B64Len: " + bencoded64.length() + "\n");
-				tv.append(bencoded64 + "\n");
-				tv.append(bencoded + "\n\n");
 
-				final String data = "ssss-android:" + bencoded64;
+				si[n] = Renderer.decodeShareInfo(data, pi);
+/*
 				if (i == 0) {
 					View view = activity.getLayoutInflater().inflate(R.layout.address_qr, null);
 					final TextView tv = (TextView) view.findViewById(R.id.secret_text);
@@ -259,8 +234,14 @@ public class GenerateFragment extends Fragment implements FragmentSupport {
 
 					builder.show();
 				}
+*/
 			}
-
+			List<ShareInfo> li = new ArrayList<ShareInfo>();
+			li.add(si[0]);
+			li.add(si[1]);
+			li.add(si[2]);
+			final SecretShare.CombineOutput combineOutput = new SecretShare(pi)
+					.combine(li);
 			this.finished = true;
 		}
 	}

app/src/main/java/org/surfsite/android/secretshare/Renderer.java

@@ -9,12 +9,17 @@ import android.graphics.Rect;
 import android.os.AsyncTask;
 import android.support.v4.print.PrintHelper;
 import android.text.TextPaint;
+import android.util.Base64;
 
 import com.google.zxing.BarcodeFormat;
 import com.google.zxing.EncodeHintType;
 import com.google.zxing.aztec.AztecWriter;
 import com.google.zxing.common.BitMatrix;
+import com.tiemens.secretshare.engine.SecretShare;
 
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
+import java.security.InvalidParameterException;
 import java.util.ArrayList;
 import java.util.Hashtable;
 
@@ -180,4 +185,87 @@ public class Renderer {
 		return lines;
 	}
 
+	static BigInteger stringToBigInteger(String in) {
+		return new BigInteger(in.getBytes());
+	}
+
+	public static String encodeShareInfo(final SecretShare.ShareInfo piece) {
+		final SecretShare.PublicInfo publicInfo = piece.getPublicInfo();
+		final byte[] bytePrimeModulus = publicInfo.getPrimeModulus().toByteArray();
+		final byte[] byteShare = piece.getShare().toByteArray();
+		final byte[] byteDescription = publicInfo.getDescription().getBytes();
+		final int byteLen = 4 + 4 + 4
+				+ (4 + byteDescription.length)
+				+ (4 + bytePrimeModulus.length)
+				+ (4 + byteShare.length);
+		final ByteBuffer byteBuffer = ByteBuffer.allocate(byteLen);
+		byteBuffer.putInt(piece.getX());
+		byteBuffer.putInt(publicInfo.getK());
+		byteBuffer.putInt(publicInfo.getN());
+		byteBuffer.putInt(byteDescription.length).put(byteDescription);
+		byteBuffer.putInt(bytePrimeModulus.length).put(bytePrimeModulus);
+		byteBuffer.putInt(byteShare.length).put(byteShare);
+		final String byteEncoded64 = Base64.encodeToString(byteBuffer.array(), Base64.DEFAULT);
+
+		return "ssss-android:" + piece.getX() + "/" + publicInfo.getK()
+				+ ":" + publicInfo.getN() + "=" + byteEncoded64;
+	}
+
+	public static SecretShare.PublicInfo decodePublicInfo(final String buf) {
+		int index64 = buf.indexOf("=") + 1;
+		String substr = buf.substring(index64);
+		final byte[] decodeBytes = Base64.decode(substr, Base64.DEFAULT);
+		final ByteBuffer byteBuffer = ByteBuffer.wrap(decodeBytes);
+		int x = byteBuffer.getInt();
+		int k = byteBuffer.getInt();
+		int n = byteBuffer.getInt();
+		int byteDescriptionLength = byteBuffer.getInt();
+		final byte[] byteDescription = new byte[byteDescriptionLength];
+		byteBuffer.get(byteDescription);
+		int bytePrimeModulusLength = byteBuffer.getInt();
+		final byte[] bytePrimeModulus = new byte[bytePrimeModulusLength];
+		byteBuffer.get(bytePrimeModulus);
+		BigInteger inPrimeModulus = new BigInteger(bytePrimeModulus);
+		return new SecretShare.PublicInfo(n, k, inPrimeModulus, new String(byteDescription));
+	}
+
+	public static SecretShare.ShareInfo decodeShareInfo(final String buf, final SecretShare.PublicInfo publicInfo) throws InvalidParameterException {
+		int index64 = buf.indexOf("=") + 1;
+		final ByteBuffer byteBuffer = ByteBuffer.wrap(Base64.decode(buf.substring(index64), Base64.DEFAULT));
+		int x = byteBuffer.getInt();
+		int k = byteBuffer.getInt();
+		int n = byteBuffer.getInt();
+
+		if (n != publicInfo.getN()) {
+			throw new InvalidParameterException("SecretShare.PublicInfo.N does not match.");
+		}
+
+		if (k != publicInfo.getK()) {
+			throw new InvalidParameterException("SecretShare.PublicInfo.K does not match.");
+		}
+
+		if (x > n) {
+			throw new InvalidParameterException("SecretShare x > n.");
+		}
+
+		int byteDescriptionLength = byteBuffer.getInt();
+		final byte[] byteDescription = new byte[byteDescriptionLength];
+		byteBuffer.get(byteDescription);
+		if (publicInfo.getDescription().compareTo(new String(byteDescription)) != 0) {
+			throw new InvalidParameterException("SecretShare.PublicInfo.Description does not match.");
+		}
+		int bytePrimeModulusLength = byteBuffer.getInt();
+		final byte[] bytePrimeModulus = new byte[bytePrimeModulusLength];
+		byteBuffer.get(bytePrimeModulus);
+		BigInteger inPrimeModulus = new BigInteger(bytePrimeModulus);
+		if (inPrimeModulus.compareTo(publicInfo.getPrimeModulus()) != 0) {
+			throw new InvalidParameterException("SecretShare.PublicInfo.PrimeModulus does not match.");
+		}
+		int byteShareLength = byteBuffer.getInt();
+		final byte[] byteShare = new byte[byteShareLength];
+		byteBuffer.get(byteShare);
+		BigInteger inShare = new BigInteger(byteShare);
+		return new SecretShare.ShareInfo(x, inShare, publicInfo);
+	}
+
 }