1 files changed, 98 insertions, 0 deletions
diff --git a/src/main/java/org/whispersystems/libaxolotl/ecc/Curve25519.java b/src/main/java/org/whispersystems/libaxolotl/ecc/Curve25519.java
new file mode 100644
index 00000000..685a4a11
--- /dev/null
+++ b/src/main/java/org/whispersystems/libaxolotl/ecc/Curve25519.java
@@ -0,0 +1,98 @@
+/**
+ * Copyright (C) 2013 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.libaxolotl.ecc;
+
+import org.whispersystems.libaxolotl.InvalidKeyException;
+
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+
+public class Curve25519 {
+
+  static {
+    System.loadLibrary("curve25519");
+
+    try {
+      random = SecureRandom.getInstance("SHA1PRNG");
+    } catch (NoSuchAlgorithmException e) {
+      throw new AssertionError(e);
+    }
+  }
+
+  private static final SecureRandom random;
+
+  private static native byte[] calculateAgreement(byte[] ourPrivate, byte[] theirPublic);
+  private static native byte[] generatePublicKey(byte[] privateKey);
+  private static native byte[] generatePrivateKey(byte[] random);
+
+  private static native byte[]  calculateSignature(byte[] random, byte[] privateKey, byte[] message);
+  private static native boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature);
+
+  public static ECKeyPair generateKeyPair() {
+    byte[] privateKey = generatePrivateKey();
+    byte[] publicKey  = generatePublicKey(privateKey);
+
+    return new ECKeyPair(new DjbECPublicKey(publicKey), new DjbECPrivateKey(privateKey));
+  }
+
+  static byte[] calculateAgreement(ECPublicKey publicKey, ECPrivateKey privateKey) {
+    return calculateAgreement(((DjbECPrivateKey)privateKey).getPrivateKey(),
+                              ((DjbECPublicKey)publicKey).getPublicKey());
+  }
+
+  static byte[] calculateSignature(ECPrivateKey privateKey, byte[] message) {
+    byte[] random = getRandom(64);
+    return calculateSignature(random, ((DjbECPrivateKey)privateKey).getPrivateKey(), message);
+  }
+
+  static boolean verifySignature(ECPublicKey publicKey, byte[] message, byte[] signature) {
+    return verifySignature(((DjbECPublicKey)publicKey).getPublicKey(), message, signature);
+  }
+
+  static ECPublicKey decodePoint(byte[] encoded, int offset)
+      throws InvalidKeyException
+  {
+    int    type     = encoded[offset] & 0xFF;
+    byte[] keyBytes = new byte[32];
+    System.arraycopy(encoded, offset+1, keyBytes, 0, keyBytes.length);
+
+    if (type != Curve.DJB_TYPE) {
+      throw new InvalidKeyException("Bad key type: " + type);
+    }
+
+    return new DjbECPublicKey(keyBytes);
+  }
+
+  private static byte[] generatePrivateKey() {
+    byte[] privateKey = new byte[32];
+    random.nextBytes(privateKey);
+
+    return generatePrivateKey(privateKey);
+  }
+
+  private static byte[] getRandom(int size) {
+    try {
+      byte[] random = new byte[size];
+      SecureRandom.getInstance("SHA1PRNG").nextBytes(random);
+
+      return random;
+    } catch (NoSuchAlgorithmException e) {
+      throw new AssertionError(e);
+    }
+  }
+
+}