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// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////
package com.google.crypto.tink.subtle;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.fail;
import com.google.crypto.tink.Aead;
import com.google.crypto.tink.testing.TestUtil;
import com.google.crypto.tink.testing.TestUtil.BytesMutation;
import com.google.crypto.tink.testing.WycheproofTestUtil;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.util.Arrays;
import java.util.HashSet;
import javax.crypto.AEADBadTagException;
import org.json.JSONArray;
import org.json.JSONObject;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
/** Unit tests for ChaCha20Poly1305. */
@RunWith(JUnit4.class)
public class ChaCha20Poly1305Test {
private static final int KEY_SIZE = 32;
public Aead createInstance(final byte[] key) throws InvalidKeyException {
return new ChaCha20Poly1305(key);
}
@Test
public void testSnufflePoly1305ThrowsIllegalArgExpWhenKeyLenIsGreaterThan32()
throws InvalidKeyException {
try {
createInstance(new byte[KEY_SIZE + 1]);
fail("Expected InvalidKeyException.");
} catch (InvalidKeyException e) {
assertThat(e).hasMessageThat().containsMatch("The key length in bytes must be 32.");
}
}
@Test
public void testSnufflePoly1305ThrowsIllegalArgExpWhenKeyLenIsLessThan32()
throws InvalidKeyException {
try {
createInstance(new byte[KEY_SIZE - 1]);
fail("Expected InvalidKeyException.");
} catch (InvalidKeyException e) {
assertThat(e).hasMessageThat().containsMatch("The key length in bytes must be 32.");
}
}
@Test
public void testDecryptThrowsGeneralSecurityExpWhenCiphertextIsTooShort()
throws InvalidKeyException {
Aead cipher = createInstance(new byte[KEY_SIZE]);
try {
cipher.decrypt(new byte[27], new byte[1]);
fail("Expected GeneralSecurityException.");
} catch (GeneralSecurityException e) {
assertThat(e).hasMessageThat().containsMatch("ciphertext too short");
}
}
@Test
public void testEncryptDecrypt() throws Exception {
Aead aead = createInstance(Random.randBytes(KEY_SIZE));
for (int i = 0; i < 100; i++) {
byte[] message = Random.randBytes(i);
byte[] aad = Random.randBytes(i);
byte[] ciphertext = aead.encrypt(message, aad);
byte[] decrypted = aead.decrypt(ciphertext, aad);
assertArrayEquals(message, decrypted);
}
}
@Test
/** BC had a bug, where GCM failed for messages of size > 8192 */
public void testLongMessages() throws Exception {
if (TestUtil.isAndroid()) {
System.out.println("testLongMessages doesn't work on Android, skipping");
return;
}
int dataSize = 16;
while (dataSize <= (1 << 24)) {
byte[] plaintext = Random.randBytes(dataSize);
byte[] aad = Random.randBytes(dataSize / 3);
byte[] key = Random.randBytes(KEY_SIZE);
Aead aead = createInstance(key);
byte[] ciphertext = aead.encrypt(plaintext, aad);
byte[] decrypted = aead.decrypt(ciphertext, aad);
assertArrayEquals(plaintext, decrypted);
dataSize += 5 * dataSize / 11;
}
}
@Test
public void testModifyCiphertext() throws Exception {
byte[] key = Random.randBytes(KEY_SIZE);
Aead aead = createInstance(key);
byte[] aad = Random.randBytes(16);
byte[] message = Random.randBytes(32);
byte[] ciphertext = aead.encrypt(message, aad);
for (BytesMutation mutation : TestUtil.generateMutations(ciphertext)) {
try {
byte[] unused = aead.decrypt(mutation.value, aad);
fail(
String.format(
"Decrypting modified ciphertext should fail : ciphertext = %s, aad = %s,"
+ " description = %s",
Hex.encode(mutation.value), Arrays.toString(aad), mutation.description));
} catch (GeneralSecurityException ex) {
// This is expected.
// This could be a AeadBadTagException when the tag verification
// fails or some not yet specified Exception when the ciphertext is too short.
// In all cases a GeneralSecurityException or a subclass of it must be thrown.
}
}
// Modify AAD
for (int b = 0; b < aad.length; b++) {
for (int bit = 0; bit < 8; bit++) {
byte[] modified = Arrays.copyOf(aad, aad.length);
modified[b] ^= (byte) (1 << bit);
try {
byte[] unused = aead.decrypt(ciphertext, modified);
fail("Decrypting with modified aad should fail");
} catch (AEADBadTagException ex) {
// This is expected.
}
}
}
}
@Test
public void testNullPlaintextOrCiphertext() throws Exception {
Aead aead = createInstance(Random.randBytes(KEY_SIZE));
try {
byte[] aad = new byte[] {1, 2, 3};
byte[] unused = aead.encrypt(null, aad);
fail("Encrypting a null plaintext should fail");
} catch (NullPointerException ex) {
// This is expected.
}
try {
byte[] unused = aead.encrypt(null, null);
fail("Encrypting a null plaintext should fail");
} catch (NullPointerException ex) {
// This is expected.
}
try {
byte[] aad = new byte[] {1, 2, 3};
byte[] unused = aead.decrypt(null, aad);
fail("Decrypting a null ciphertext should fail");
} catch (NullPointerException ex) {
// This is expected.
}
try {
byte[] unused = aead.decrypt(null, null);
fail("Decrypting a null ciphertext should fail");
} catch (NullPointerException ex) {
// This is expected.
}
}
@Test
public void testEmptyAssociatedData() throws Exception {
byte[] aad = new byte[0];
Aead aead = createInstance(Random.randBytes(KEY_SIZE));
for (int messageSize = 0; messageSize < 75; messageSize++) {
byte[] message = Random.randBytes(messageSize);
{ // encrypting with aad as a 0-length array
byte[] ciphertext = aead.encrypt(message, aad);
byte[] decrypted = aead.decrypt(ciphertext, aad);
assertArrayEquals(message, decrypted);
byte[] decrypted2 = aead.decrypt(ciphertext, null);
assertArrayEquals(message, decrypted2);
try {
byte[] badAad = new byte[] {1, 2, 3};
byte[] unused = aead.decrypt(ciphertext, badAad);
fail("Decrypting with modified aad should fail");
} catch (AEADBadTagException ex) {
// This is expected.
}
}
{ // encrypting with aad equal to null
byte[] ciphertext = aead.encrypt(message, null);
byte[] decrypted = aead.decrypt(ciphertext, aad);
assertArrayEquals(message, decrypted);
byte[] decrypted2 = aead.decrypt(ciphertext, null);
assertArrayEquals(message, decrypted2);
try {
byte[] badAad = new byte[] {1, 2, 3};
byte[] unused = aead.decrypt(ciphertext, badAad);
fail("Decrypting with modified aad should fail");
} catch (AEADBadTagException ex) {
// This is expected.
}
}
}
}
/**
* This is a very simple test for the randomness of the nonce. The test simply checks that the
* multiple ciphertexts of the same message are distinct.
*/
@Test
public void testRandomNonce() throws Exception {
byte[] key = Random.randBytes(KEY_SIZE);
Aead aead = createInstance(key);
byte[] message = new byte[0];
byte[] aad = new byte[0];
HashSet<String> ciphertexts = new HashSet<String>();
final int samples = 1 << 10;
for (int i = 0; i < samples; i++) {
byte[] ct = aead.encrypt(message, aad);
String ctHex = TestUtil.hexEncode(ct);
assertFalse(ciphertexts.contains(ctHex));
ciphertexts.add(ctHex);
}
assertEquals(samples, ciphertexts.size());
}
@Test
public void testWycheproofVectors() throws Exception {
JSONObject json =
WycheproofTestUtil.readJson(
"../wycheproof/testvectors/chacha20_poly1305_test.json");
int errors = 0;
JSONArray testGroups = json.getJSONArray("testGroups");
for (int i = 0; i < testGroups.length(); i++) {
JSONObject group = testGroups.getJSONObject(i);
JSONArray tests = group.getJSONArray("tests");
for (int j = 0; j < tests.length(); j++) {
JSONObject testcase = tests.getJSONObject(j);
String tcId =
String.format(
"testcase %d (%s)", testcase.getInt("tcId"), testcase.getString("comment"));
byte[] iv = Hex.decode(testcase.getString("iv"));
byte[] key = Hex.decode(testcase.getString("key"));
byte[] msg = Hex.decode(testcase.getString("msg"));
byte[] aad = Hex.decode(testcase.getString("aad"));
byte[] ct = Hex.decode(testcase.getString("ct"));
byte[] tag = Hex.decode(testcase.getString("tag"));
byte[] ciphertext = Bytes.concat(iv, ct, tag);
// Result is one of "valid", "invalid", "acceptable".
// "valid" are test vectors with matching plaintext, ciphertext and tag.
// "invalid" are test vectors with invalid parameters or invalid ciphertext and tag.
// "acceptable" are test vectors with weak parameters or legacy formats.
String result = testcase.getString("result");
try {
Aead aead = createInstance(key);
byte[] decrypted = aead.decrypt(ciphertext, aad);
boolean eq = TestUtil.arrayEquals(decrypted, msg);
if (result.equals("invalid")) {
System.out.printf(
"FAIL %s: accepting invalid ciphertext, cleartext: %s, decrypted: %s%n",
tcId, Hex.encode(msg), Hex.encode(decrypted));
errors++;
} else {
if (!eq) {
System.out.printf(
"FAIL %s: incorrect decryption, result: %s, expected: %s%n",
tcId, Hex.encode(decrypted), Hex.encode(msg));
errors++;
}
}
} catch (GeneralSecurityException ex) {
if (result.equals("valid")) {
System.out.printf("FAIL %s: cannot decrypt, exception %s%n", tcId, ex);
errors++;
}
}
}
}
assertEquals(0, errors);
}
}