Refactored into provider model for initial support of J2ME.

Author: moxie0

android/src/androidTest/java/org/whispersystems/curve25519/NativeCurve25519ProviderTest.java

@@ -2,7 +2,7 @@
 
 public class NativeCurve25519ProviderTest extends Curve25519ProviderTest {
   @Override
-  protected Curve25519Provider createProvider() {
+  protected Curve25519Provider createProvider() throws NoSuchProviderException {
     return new NativeCurve25519Provider();
   }
 }

android/src/androidTest/java/org/whispersystems/curve25519/NativeCurve25519Test.java

@@ -3,8 +3,13 @@
 public class NativeCurve25519Test extends Curve25519Test {
 
   @Override
-  public void testCheckProvider() {
-    assertTrue(Curve25519.isNative());
+  public void testCheckProvider() throws NoSuchProviderException {
+    assertTrue(Curve25519.getInstance(getProviderName()).isNative());
+  }
+
+  @Override
+  public String getProviderName() {
+    return "native";
   }
 
 }

common/build.gradle

@@ -0,0 +1,3 @@
+apply plugin: 'java'
+
+sourceCompatibility = 1.2

common/src/main/java/org/whispersystems/curve25519/BaseJavaCurve25519Provider.java

@@ -0,0 +1,83 @@
+/**
+ * Copyright (C) 2015 Open Whisper Systems
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.whispersystems.curve25519;
+
+import org.whispersystems.curve25519.java.Sha512;
+import org.whispersystems.curve25519.java.curve_sigs;
+import org.whispersystems.curve25519.java.scalarmult;
+
+abstract class BaseJavaCurve25519Provider implements Curve25519Provider {
+
+  // @Override
+  public boolean isNative() {
+    return false;
+  }
+
+  // @Override
+  public byte[] calculateAgreement(byte[] ourPrivate, byte[] theirPublic) {
+    byte[] agreement = new byte[32];
+    scalarmult.crypto_scalarmult(agreement, ourPrivate, theirPublic);
+
+    return agreement;
+  }
+
+  // @Override
+  public byte[] generatePublicKey(byte[] privateKey) {
+    byte[] publicKey = new byte[32];
+    curve_sigs.curve25519_keygen(publicKey, privateKey);
+
+    return publicKey;
+  }
+
+  //  @Override
+  public byte[] generatePrivateKey() {
+    byte[] random = getRandom(PRIVATE_KEY_LEN);
+    return generatePrivateKey(random);
+  }
+
+  // @Override
+  public byte[] generatePrivateKey(byte[] random) {
+    byte[] privateKey = new byte[32];
+
+    System.arraycopy(random, 0, privateKey, 0, 32);
+
+    privateKey[0]  &= 248;
+    privateKey[31] &= 127;
+    privateKey[31] |= 64;
+
+    return privateKey;
+  }
+
+  // @Override
+  public byte[] calculateSignature(byte[] random, byte[] privateKey, byte[] message) {
+    byte[] result = new byte[64];
+
+    if (curve_sigs.curve25519_sign(getSha512(), result, privateKey, message, message.length, random) != 0) {
+      throw new IllegalArgumentException("Message exceeds max length!");
+    }
+
+    return result;
+  }
+
+  // @Override
+  public boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature) {
+    return curve_sigs.curve25519_verify(getSha512(), signature, publicKey, message, message.length) == 0;
+  }
+
+  protected abstract Sha512 getSha512();
+
+}

common/src/main/java/org/whispersystems/curve25519/Curve25519.java

@@ -0,0 +1,155 @@
+/**
+ * Copyright (C) 2015 Open Whisper Systems
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.whispersystems.curve25519;
+
+/**
+ * A Curve25519 interface for generating keys, calculating agreements, creating signatures,
+ * and verifying signatures.
+ *
+ * @author Moxie Marlinspike
+ */
+public class Curve25519 {
+
+  public static final String NATIVE = "native";
+  public static final String JAVA   = "java";
+  public static final String J2ME   = "j2me";
+  public static final String BEST   = "best";
+
+  public static Curve25519 getInstance(String type) throws NoSuchProviderException {
+    if      (NATIVE.equals(type)) return new Curve25519(constructNativeProvider());
+    else if (JAVA.equals(type))   return new Curve25519(constructJavaProvider());
+    else if (J2ME.equals(type))   return new Curve25519(constructJ2meProvider());
+    else if (BEST.equals(type))   return new Curve25519(constructOpportunisticProvider());
+    else                          throw new NoSuchProviderException(type);
+  }
+
+  private final Curve25519Provider provider;
+
+  private Curve25519(Curve25519Provider provider) {
+    this.provider = provider;
+  }
+
+
+//  static {
+//    try {
+//      provider = new NativeCurve25519Provider();
+//    } catch (UnsatisfiedLinkError ule) {
+//      provider = new JavaCurve25519Provider();
+//    }
+//  }
+
+  /**
+   * {@link Curve25519} is backed by either a native (via JNI)
+   * or pure-Java provider.  By default it prefers the native provider, and falls back to the
+   * pure-Java provider if the native library fails to load.
+   *
+   * @return true if backed by a native provider, false otherwise.
+   */
+  public boolean isNative() {
+    return provider.isNative();
+  }
+
+  /**
+   * Generates a Curve25519 keypair.
+   *
+   * @return A randomly generated Curve25519 keypair.
+   */
+  public Curve25519KeyPair generateKeyPair() {
+    byte[] privateKey = provider.generatePrivateKey();
+    byte[] publicKey  = provider.generatePublicKey(privateKey);
+
+    return new Curve25519KeyPair(publicKey, privateKey);
+  }
+
+  /**
+   * Calculates an ECDH agreement.
+   *
+   * @param publicKey The Curve25519 (typically remote party's) public key.
+   * @param privateKey The Curve25519 (typically yours) private key.
+   * @return A 32-byte shared secret.
+   */
+  public byte[] calculateAgreement(byte[] publicKey, byte[] privateKey) {
+    return provider.calculateAgreement(privateKey, publicKey);
+  }
+
+  /**
+   * Calculates a Curve25519 signature.
+   *
+   * @param privateKey The private Curve25519 key to create the signature with.
+   * @param message The message to sign.
+   * @return A 64-byte signature.
+   */
+  public byte[] calculateSignature(byte[] privateKey, byte[] message) {
+    byte[] random = provider.getRandom(64);
+    return provider.calculateSignature(random, privateKey, message);
+  }
+
+  /**
+   * Verify a Curve25519 signature.
+   *
+   * @param publicKey The Curve25519 public key the signature belongs to.
+   * @param message The message that was signed.
+   * @param signature The signature to verify.
+   * @return true if valid, false if not.
+   */
+  public boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature) {
+    return provider.verifySignature(publicKey, message, signature);
+  }
+
+//  private byte[] generatePrivateKey() {
+//    byte[] privateKey = new byte[32];
+//    random.nextBytes(privateKey);
+//
+//    return provider.generatePrivateKey(privateKey);
+//  }
+
+//  private byte[] getRandom(SecureRandom secureRandom, int size) {
+//    byte[] output = new byte[size];
+//    secureRandom.nextBytes(output);
+//
+//    return output;
+//  }
+
+  private static Curve25519Provider constructNativeProvider() throws NoSuchProviderException {
+    return constructClass("NativeCurve25519Provider");
+  }
+
+  private static Curve25519Provider constructJavaProvider() throws NoSuchProviderException {
+    return constructClass("JavaCurve25519Provider");
+  }
+
+  private static Curve25519Provider constructJ2meProvider() throws NoSuchProviderException {
+    return constructClass("J2meCurve25519Provider");
+  }
+
+  private static Curve25519Provider constructOpportunisticProvider() throws NoSuchProviderException {
+    return constructClass("OpportunisticCurve25519Provider");
+  }
+
+  private static Curve25519Provider constructClass(String name) throws NoSuchProviderException {
+    try {
+      return (Curve25519Provider)Class.forName("org.whispersystems.curve25519." + name).newInstance();
+    } catch (InstantiationException e) {
+      throw new NoSuchProviderException(e);
+    } catch (IllegalAccessException e) {
+      throw new NoSuchProviderException(e);
+    } catch (ClassNotFoundException e) {
+      throw new NoSuchProviderException(e);
+    }
+  }
+
+}

java/src/main/java/org/whispersystems/curve25519/Curve25519KeyPair.java renamed to common/src/main/java/org/whispersystems/curve25519/Curve25519KeyPair.java

@@ -18,10 +18,14 @@
 
 interface Curve25519Provider {
 
+  static final int PRIVATE_KEY_LEN = 32;
+
   boolean isNative();
   byte[] calculateAgreement(byte[] ourPrivate, byte[] theirPublic);
   byte[] generatePublicKey(byte[] privateKey);
+  byte[] generatePrivateKey();
   byte[] generatePrivateKey(byte[] random);
+  byte[] getRandom(int length);
 
   byte[]  calculateSignature(byte[] random, byte[] privateKey, byte[] message);
   boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature);

java/src/main/java/org/whispersystems/curve25519/Curve25519Provider.java renamed to common/src/main/java/org/whispersystems/curve25519/Curve25519Provider.java

@@ -0,0 +1,11 @@
+package org.whispersystems.curve25519;
+
+public class NoSuchProviderException extends Exception {
+  public NoSuchProviderException(Throwable e) {
+    super(e);
+  }
+
+  public NoSuchProviderException(String type) {
+    super(type);
+  }
+}

common/src/main/java/org/whispersystems/curve25519/NoSuchProviderException.java

@@ -0,0 +1,16 @@
+package org.whispersystems.curve25519.java;
+
+public class Arrays {
+  /**
+   * Assigns the specified byte value to each element of the specified array
+   * of bytes.
+   *
+   * @param a the array to be filled
+   * @param val the value to be stored in all elements of the array
+   */
+  public static void fill(byte[] a, byte val) {
+    for (int i = 0, len = a.length; i < len; i++)
+      a[i] = val;
+  }
+
+}

common/src/main/java/org/whispersystems/curve25519/java/Arrays.java

@@ -0,0 +1,7 @@
+package org.whispersystems.curve25519.java;
+
+public interface Sha512 {
+
+  public void calculateDigest(byte[] out, byte[] in, long length);
+
+}