1 files changed, 77 insertions, 0 deletions
diff --git a/contrib/Curve25519Donna.java b/contrib/Curve25519Donna.java
new file mode 100644
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--- /dev/null
+++ b/contrib/Curve25519Donna.java
@@ -0,0 +1,77 @@
+/*
+    James Robson
+    Public domain.
+*/
+
+public class Curve25519Donna {
+
+    final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
+
+    public static String bytesToHex(byte[] bytes) {
+        char[] hexChars = new char[bytes.length * 2];
+        int v;
+        for ( int j = 0; j < bytes.length; j++ ) {
+            v = bytes[j] & 0xFF;
+            hexChars[j * 2] = hexArray[v >>> 4];
+            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
+        }
+        return new String(hexChars);
+    }
+
+    public native byte[] curve25519Donna(byte[] a, byte[] b);
+    public native byte[] makePrivate(byte[] secret);
+    public native byte[] getPublic(byte[] privkey);
+    public native byte[] makeSharedSecret(byte[] privkey, byte[] theirPubKey);
+    public native void helowrld();
+
+    // Uncomment if your Java is 32-bit:
+    //static { System.loadLibrary("Curve25519Donna"); }
+
+    // Otherwise, load this 64-bit .jnilib:
+    static { System.loadLibrary("Curve25519Donna_64"); }
+
+    /*
+        To give the old tires a kick (OSX):
+        java -cp `pwd` Curve25519Donna
+    */
+    public static void main (String[] args) {
+
+        Curve25519Donna c = new Curve25519Donna();
+
+        // These should be 32 bytes long
+        byte[] user1Secret = "abcdefghijklmnopqrstuvwxyz123456".getBytes();
+        byte[] user2Secret = "654321zyxwvutsrqponmlkjihgfedcba".getBytes();
+
+
+        // You can use the curve function directly...
+
+        //byte[] o = c.curve25519Donna(a, b);
+        //System.out.println("o = " + bytesToHex(o));
+
+
+        // ... but it's not really necessary. Just use the following
+        // convenience methods:
+
+        byte[] privKey = c.makePrivate(user1Secret);
+        byte[] pubKey = c.getPublic(privKey);
+
+        byte[] privKey2 = c.makePrivate(user2Secret);
+        byte[] pubKey2 = c.getPublic(privKey2);
+
+        System.out.println("'user1' privKey = " + bytesToHex(privKey));
+        System.out.println("'user1' pubKey = " + bytesToHex(pubKey));
+        System.out.println("===================================================");
+
+        System.out.println("'user2' privKey = " + bytesToHex(privKey2));
+        System.out.println("'user2' pubKey = " + bytesToHex(pubKey2));
+        System.out.println("===================================================");
+
+
+        byte[] ss1 = c.makeSharedSecret(privKey, pubKey2);
+        System.out.println("'user1' computes shared secret: " + bytesToHex(ss1));
+
+        byte[] ss2 = c.makeSharedSecret(privKey2, pubKey);
+        System.out.println("'user2' computes shared secret: " + bytesToHex(ss2));
+
+    }
+}