Create ChaCha20Test.java

Author: Keykyrios

src/test/java/com/thealgorithms/ciphers/ChaCha20Test.java

@@ -0,0 +1,132 @@
+package com.thealgorithms.ciphers;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class ChaCha20Test {
+
+    // Test vector from RFC 8439, Section 2.4.2.
+    private static final byte[] RFC8439_KEY = hexStringToByteArray("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f");
+    private static final byte[] RFC8439_NONCE = hexStringToByteArray("000000000000004a00000000"); // Counter = 1, Nonce = 00000000 0000004a 00000000
+    private static final byte[] RFC8439_PLAINTEXT_64 = hexStringToByteArray(
+        "4c616469657320616e642047656e746c656d656e206f662074686520636c617373206f66202739393a204966204920636f756c64206f6666657220796f75206f6e6c79206f6e652074697020666f7220746865206675747572652c2073756e73637265656e20776f756c642062652069742e"
+    );
+    private static final byte[] RFC8439_CIPHERTEXT_64 = hexStringToByteArray(
+        "6e2e359a2568f98041ba0728dd0d6981e97e7aec1d4360c20a27afccfd9fae0bf91b65c5524733ab8f58375fcd4af034bd16adec164f7a2bda3dc0343a99a46c8b4172421b505877c570b1351d530635359a37e5f1797b596a78c149d5d9963e696f8c792374c4314c67d163f97205463f668f438a0c20a3a7187"
+    );
+
+    // Test vector from RFC 8439, Section 2.4.2 for 114 bytes
+    private static final byte[] RFC8439_PLAINTEXT_114 = Arrays.copyOf(RFC8439_PLAINTEXT_64, 114);
+    private static final byte[] RFC8439_CIPHERTEXT_114 = Arrays.copyOf(RFC8439_CIPHERTEXT_64, 114);
+
+    @Test
+    public void testEncryptRFC8439Vector64Bytes() {
+        byte[] ciphertext = ChaCha20.encrypt(RFC8439_KEY, RFC8439_NONCE, RFC8439_PLAINTEXT_64);
+        assertArrayEquals(RFC8439_CIPHERTEXT_64, ciphertext);
+    }
+
+    @Test
+    public void testDecryptRFC8439Vector64Bytes() {
+        byte[] plaintext = ChaCha20.decrypt(RFC8439_KEY, RFC8439_NONCE, RFC8439_CIPHERTEXT_64);
+        assertArrayEquals(RFC8439_PLAINTEXT_64, plaintext);
+    }
+
+    @Test
+    public void testEncryptRFC8439Vector114Bytes() {
+        // Test encryption with plaintext length not a multiple of 64
+        byte[] ciphertext = ChaCha20.encrypt(RFC8439_KEY, RFC8439_NONCE, RFC8439_PLAINTEXT_114);
+        assertArrayEquals(RFC8439_CIPHERTEXT_114, ciphertext);
+    }
+
+    @Test
+    public void testDecryptRFC8439Vector114Bytes() {
+        // Test decryption with ciphertext length not a multiple of 64
+        byte[] plaintext = ChaCha20.decrypt(RFC8439_KEY, RFC8439_NONCE, RFC8439_CIPHERTEXT_114);
+        assertArrayEquals(RFC8439_PLAINTEXT_114, plaintext);
+    }
+
+    @Test
+    public void testEncryptDecryptSymmetry() {
+        byte[] key = new byte[32];
+        for (int i = 0; i < 32; i++) {
+            key[i] = (byte) i;
+        }
+        byte[] nonce = new byte[12];
+        for (int i = 0; i < 12; i++) {
+            nonce[i] = (byte) (i + 100);
+        }
+        String originalText = "This is a test message to verify encrypt/decrypt symmetry.";
+        byte[] plaintext = originalText.getBytes();
+
+        byte[] ciphertext = ChaCha20.encrypt(key, nonce, plaintext);
+        byte[] decryptedText = ChaCha20.decrypt(key, nonce, ciphertext);
+
+        assertArrayEquals(plaintext, decryptedText);
+        assertEquals(originalText, new String(decryptedText));
+    }
+
+    @Test
+    public void testEmptyPlaintext() {
+        byte[] empty = new byte[0];
+        byte[] ciphertext = ChaCha20.encrypt(RFC8439_KEY, RFC8439_NONCE, empty);
+        assertArrayEquals(empty, ciphertext);
+        byte[] plaintext = ChaCha20.decrypt(RFC8439_KEY, RFC8439_NONCE, empty);
+        assertArrayEquals(empty, plaintext);
+    }
+
+    @Test
+    public void testInvalidKeySize() {
+        byte[] shortKey = new byte[31];
+        byte[] longKey = new byte[33];
+        byte[] nonce = new byte[12];
+        byte[] data = {1, 2, 3};
+
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(shortKey, nonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(longKey, nonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(shortKey, nonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(longKey, nonce, data));
+    }
+
+    @Test
+    public void testInvalidNonceSize() {
+        byte[] key = new byte[32];
+        byte[] shortNonce = new byte[11];
+        byte[] longNonce = new byte[13];
+        byte[] data = {1, 2, 3};
+
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(key, shortNonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(key, longNonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(key, shortNonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(key, longNonce, data));
+    }
+
+    @Test
+    public void testNullInputs() {
+        byte[] key = new byte[32];
+        byte[] nonce = new byte[12];
+        byte[] data = {1, 2, 3};
+
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(null, nonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(key, null, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.encrypt(key, nonce, null));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(null, nonce, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(key, null, data));
+        assertThrows(IllegalArgumentException.class, () -> ChaCha20.decrypt(key, nonce, null));
+    }
+
+    // Helper to convert hex string to byte array for test vectors
+    private static byte[] hexStringToByteArray(String s) {
+        int len = s.length();
+        if (len % 2 != 0) {
+            throw new IllegalArgumentException("Hex string must have even length");
+        }
+        byte[] data = new byte[len / 2];
+        for (int i = 0; i < len; i += 2) {
+            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i + 1), 16));
+        }
+        return data;
+    }
+}