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