/* * Copyright (C) 2017 The Android Open Source Project * * 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 android.privacy; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; import android.privacy.internal.rappor.RapporConfig; import android.privacy.internal.rappor.RapporEncoder; import androidx.test.filters.SmallTest; import androidx.test.runner.AndroidJUnit4; import org.junit.Test; import org.junit.runner.RunWith; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.charset.StandardCharsets; import java.security.MessageDigest; /** * Unit test for the {@link RapporEncoder}. * Most of the tests are done in external/rappor/client/javatest/ already. * Tests here are just make sure the {@link RapporEncoder} wrap Rappor correctly. */ @RunWith(AndroidJUnit4.class) @SmallTest public class RapporEncoderTest { @Test public void testRapporEncoder_config() throws Exception { final RapporConfig config = new RapporConfig( "Foo", // encoderId 8, // numBits, 13.0 / 128.0, // probabilityF 0.25, // probabilityP 0.75, // probabilityQ 1, // numCohorts 2); // numBloomHashes) final RapporEncoder encoder = RapporEncoder.createEncoder(config, makeTestingUserSecret("encoder1")); assertEquals("Rappor", encoder.getConfig().getAlgorithm()); assertEquals("EncoderId: Foo, NumBits: 8, ProbabilityF: 0.102, " + "ProbabilityP: 0.250, ProbabilityQ: 0.750, NumCohorts: 1, " + "NumBloomHashes: 2", encoder.getConfig().toString()); } @Test public void testRapporEncoder_basicIRRTest() throws Exception { final RapporConfig config = new RapporConfig( "Foo", // encoderId 12, // numBits, 0, // probabilityF 0, // probabilityP 1, // probabilityQ 1, // numCohorts (so must be cohort 0) 2); // numBloomHashes // Use insecure encoder here as we want to get the exact output. final RapporEncoder encoder = RapporEncoder.createInsecureEncoderForTest(config); assertEquals(768, toLong(encoder.encodeString("Testing"))); } @Test public void testRapporEncoder_IRRWithPRR() throws Exception { int numBits = 8; final long inputValue = 254L; final long expectedPrrValue = 126L; final long expectedPrrAndIrrValue = 79L; final RapporConfig config1 = new RapporConfig( "Foo2", // encoderId numBits, // numBits, 0.25, // probabilityF 0, // probabilityP 1, // probabilityQ 1, // numCohorts 2); // numBloomHashes // Use insecure encoder here as we want to get the exact output. final RapporEncoder encoder1 = RapporEncoder.createInsecureEncoderForTest(config1); // Verify that PRR is working as expected. assertEquals(expectedPrrValue, toLong(encoder1.encodeBits(toBytes(inputValue)))); assertTrue(encoder1.isInsecureEncoderForTest()); // Verify that IRR is working as expected. final RapporConfig config2 = new RapporConfig( "Foo2", // encoderId numBits, // numBits, 0, // probabilityF 0.3, // probabilityP 0.7, // probabilityQ 1, // numCohorts 2); // numBloomHashes // Use insecure encoder here as we want to get the exact output. final RapporEncoder encoder2 = RapporEncoder.createInsecureEncoderForTest(config2); assertEquals(expectedPrrAndIrrValue, toLong(encoder2.encodeBits(toBytes(expectedPrrValue)))); // Test that end-to-end is the result of PRR + IRR. final RapporConfig config3 = new RapporConfig( "Foo2", // encoderId numBits, // numBits, 0.25, // probabilityF 0.3, // probabilityP 0.7, // probabilityQ 1, // numCohorts 2); // numBloomHashes final RapporEncoder encoder3 = RapporEncoder.createInsecureEncoderForTest(config3); // Verify that PRR is working as expected. assertEquals(expectedPrrAndIrrValue, toLong(encoder3.encodeBits(toBytes(inputValue)))); } @Test public void testRapporEncoder_ensureSecureEncoderIsSecure() throws Exception { int numBits = 8; final long inputValue = 254L; final long prrValue = 250L; final long prrAndIrrValue = 184L; final RapporConfig config1 = new RapporConfig( "Foo", // encoderId numBits, // numBits, 0.25, // probabilityF 0, // probabilityP 1, // probabilityQ 1, // numCohorts 2); // numBloomHashes final RapporEncoder encoder1 = RapporEncoder.createEncoder(config1, makeTestingUserSecret("secret1")); // Verify that PRR is working as expected, not affected by random seed. assertEquals(prrValue, toLong(encoder1.encodeBits(toBytes(inputValue)))); assertFalse(encoder1.isInsecureEncoderForTest()); boolean hasDifferentResult2 = false; for (int i = 0; i < 5; i++) { final RapporConfig config2 = new RapporConfig( "Foo", // encoderId numBits, // numBits, 0, // probabilityF 0.3, // probabilityP 0.7, // probabilityQ 1, // numCohorts 2); // numBloomHashes final RapporEncoder encoder2 = RapporEncoder.createEncoder(config2, makeTestingUserSecret("secret1")); hasDifferentResult2 |= (prrAndIrrValue != toLong( encoder2.encodeBits(toBytes(prrValue)))); } // Ensure it's not getting same result as it has random seed while encoder id and secret // is the same. assertTrue(hasDifferentResult2); boolean hasDifferentResults3 = false; for (int i = 0; i < 5; i++) { final RapporConfig config3 = new RapporConfig( "Foo", // encoderId numBits, // numBits, 0.25, // probabilityF 0.3, // probabilityP 0.7, // probabilityQ 1, // numCohorts 2); // numBloomHashes final RapporEncoder encoder3 = RapporEncoder.createEncoder(config3, makeTestingUserSecret("secret1")); hasDifferentResults3 |= (prrAndIrrValue != toLong( encoder3.encodeBits(toBytes(inputValue)))); } // Ensure it's not getting same result as it has random seed while encoder id and secret // is the same. assertTrue(hasDifferentResults3); } private static byte[] toBytes(long value) { return ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(value).array(); } private static long toLong(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).put(bytes); buffer.rewind(); return buffer.getLong(); } private static byte[] makeTestingUserSecret(String testingSecret) throws Exception { // We generate the fake user secret by concatenating three copies of the // 16 byte MD5 hash of the testingSecret string encoded in UTF 8. MessageDigest md5 = MessageDigest.getInstance("MD5"); byte[] digest = md5.digest(testingSecret.getBytes(StandardCharsets.UTF_8)); assertEquals(16, digest.length); return ByteBuffer.allocate(48).put(digest).put(digest).put(digest).array(); } }