Add interoperability tests

build.gradle

@@ -13,6 +13,7 @@ dependencies {
     implementation 'org.bouncycastle:bcprov-jdk18on:1.77'
     testImplementation platform('org.junit:junit-bom:5.9.1')
     testImplementation 'org.junit.jupiter:junit-jupiter'
+    testImplementation 'org.purejava:tweetnacl-java:1.1.2'
 }
 
 test {

src/test/java/io/xconn/cryptobox/InteroperabilityTest.java

@@ -0,0 +1,105 @@
+package io.xconn.cryptobox;
+
+import java.security.GeneralSecurityException;
+import java.util.Arrays;
+
+import com.iwebpp.crypto.TweetNaclFast;
+
+import org.bouncycastle.util.encoders.Hex;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+public class InteroperabilityTest {
+
+    private static final byte[] publicKey = Hex.decode("e54e7c4f75ea1cba7b276711ad2e88e7ac963502906724b86794d115df85114b");
+    private static final byte[] privateKey = Hex.decode("28cf2aaeca5db014927f3956ac3c32141b9a08164367326b549b36bc81c3ac48");
+
+    @Test
+    public void secretBoxTest() {
+        byte[] message = "Hello, World!".getBytes();
+        byte[] nonce = Util.generateRandomBytesArray(Util.NONCE_SIZE);
+
+        // encrypt using TweetNaCl
+        TweetNaclFast.SecretBox box = new TweetNaclFast.SecretBox(privateKey);
+        byte[] ct = box.box(message, nonce);
+
+        byte[] ciphertext = new byte[nonce.length + ct.length];
+        System.arraycopy(nonce, 0, ciphertext, 0, nonce.length);
+        System.arraycopy(ct, 0, ciphertext, nonce.length, ct.length);
+
+        //  decrypt using SecretBox
+        byte[] plainText = SecretBox.boxOpen(ciphertext, privateKey);
+
+        assertArrayEquals(message, plainText);
+
+        // encrypt using SecretBox
+        byte[] cipherText = SecretBox.box(message, privateKey);
+
+        byte[] nonce1 = Arrays.copyOfRange(cipherText, 0, Util.NONCE_SIZE);
+        byte[] encryptedMessage = Arrays.copyOfRange(cipherText, Util.NONCE_SIZE, cipherText.length);
+
+        // decrypt using TweetNaCl
+        byte[] decryptedMessage = box.open(encryptedMessage, nonce1);
+        assertArrayEquals(message, decryptedMessage);
+    }
+
+    @Test
+    public void sealedBoxTest() throws GeneralSecurityException {
+        byte[] message = "Hello, World!".getBytes();
+
+        // encrypt using TweetNaCl
+        byte[] ct = SealedBoxNaCl.crypto_box_seal(message);
+
+        // decrypt using SealedBox
+        byte[] plainText = SealedBox.sealOpen(ct, privateKey);
+
+        assertArrayEquals(message, plainText);
+
+        // encrypt using SealedBox
+        byte[] cipherText = SealedBox.seal(message, publicKey);
+
+        // decrypt using TweetNaCl
+        byte[] plaintext = SealedBoxNaCl.crypto_box_seal_open(cipherText, publicKey, privateKey);
+
+        assertArrayEquals(message, plaintext);
+    }
+
+    /**
+     * An implementation SealedBox using TweetNaCl.
+     * Taken from https://stackoverflow.com/a/42456750
+     */
+    static class SealedBoxNaCl{
+        static byte[] crypto_box_seal(byte[] clearText) throws GeneralSecurityException {
+            // create ephemeral keypair for sender
+            TweetNaclFast.Box.KeyPair ephkeypair = TweetNaclFast.Box.keyPair();
+            // create nonce
+            byte[] nonce = SealedBox.createNonce(ephkeypair.getPublicKey(), publicKey);
+            TweetNaclFast.Box box = new TweetNaclFast.Box(publicKey, ephkeypair.getSecretKey());
+            byte[] ciphertext = box.box(clearText, nonce);
+            if (ciphertext == null) throw new GeneralSecurityException("could not create box");
+
+            byte[] sealedbox = new byte[ciphertext.length + Util.PUBLIC_KEY_BYTES];
+            byte[] ephpubkey = ephkeypair.getPublicKey();
+
+            System.arraycopy(ephpubkey, 0, sealedbox, 0, Util.PUBLIC_KEY_BYTES);
+            System.arraycopy(ciphertext, 0, sealedbox, 32, ciphertext.length);
+
+            return sealedbox;
+        }
+
+        public static byte[] crypto_box_seal_open(byte[] c, byte[] pk, byte[] sk) throws GeneralSecurityException {
+            if (c.length < Util.PUBLIC_KEY_BYTES + Util.MAC_SIZE)
+                throw new IllegalArgumentException("Ciphertext too short");
+
+            byte[] pksender = Arrays.copyOfRange(c, 0, Util.PUBLIC_KEY_BYTES);
+            byte[] ciphertextwithmac = Arrays.copyOfRange(c, Util.PUBLIC_KEY_BYTES, c.length);
+            byte[] nonce = SealedBox.createNonce(pksender, pk);
+
+            TweetNaclFast.Box box = new TweetNaclFast.Box(pksender, sk);
+            byte[] cleartext = box.open(ciphertextwithmac, nonce);
+            if (cleartext == null) throw new GeneralSecurityException("could not open box");
+            return cleartext;
+        }
+    }
+}