/* * 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 com.google.common.truth.Truth.assertThat; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertTrue; import android.privacy.internal.longitudinalreporting.LongitudinalReportingConfig; import android.privacy.internal.longitudinalreporting.LongitudinalReportingEncoder; 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.charset.StandardCharsets; import java.security.MessageDigest; /** * Unit test for the {@link LongitudinalReportingEncoder}. * * As {@link LongitudinalReportingEncoder} is based on Rappor, * most cases are covered by Rappor tests already. */ @RunWith(AndroidJUnit4.class) @SmallTest public class LongitudinalReportingEncoderTest { @Test public void testLongitudinalReportingEncoder_config() throws Exception { final LongitudinalReportingConfig config = new LongitudinalReportingConfig( "Foo", // encoderId 0.4, // probabilityF 0.25, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder = LongitudinalReportingEncoder.createInsecureEncoderForTest( config); assertEquals("LongitudinalReporting", encoder.getConfig().getAlgorithm()); assertEquals( "EncoderId: Foo, ProbabilityF: 0.400, ProbabilityP: 0.250, ProbabilityQ: 1.000", encoder.getConfig().toString()); } @Test public void testLongitudinalReportingEncoder_basicIRRTest() throws Exception { // Test if IRR can generate expected result when seed is fixed (insecure encoder) final LongitudinalReportingConfig config = new LongitudinalReportingConfig( "Foo", // encoderId 0.4, // probabilityF 0, // probabilityP 0); // probabilityQ // Use insecure encoder here to make sure seed is set. final LongitudinalReportingEncoder encoder = LongitudinalReportingEncoder.createInsecureEncoderForTest( config); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(0, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(1, encoder.encodeBoolean(true)[0]); assertEquals(0, encoder.encodeBoolean(true)[0]); assertEquals(0, encoder.encodeBoolean(true)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(1, encoder.encodeBoolean(false)[0]); assertEquals(1, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); assertEquals(0, encoder.encodeBoolean(false)[0]); // Test if IRR returns original result when f = 0 final LongitudinalReportingConfig config2 = new LongitudinalReportingConfig( "Foo", // encoderId 0, // probabilityF 0, // probabilityP 0); // probabilityQ final LongitudinalReportingEncoder encoder2 = LongitudinalReportingEncoder.createEncoder( config2, makeTestingUserSecret("secret2")); for (int i = 0; i < 10; i++) { assertEquals(1, encoder2.encodeBoolean(true)[0]); } for (int i = 0; i < 10; i++) { assertEquals(0, encoder2.encodeBoolean(false)[0]); } // Test if IRR returns opposite result when f = 1 final LongitudinalReportingConfig config3 = new LongitudinalReportingConfig( "Foo", // encoderId 1, // probabilityF 0, // probabilityP 0); // probabilityQ final LongitudinalReportingEncoder encoder3 = LongitudinalReportingEncoder.createEncoder( config3, makeTestingUserSecret("secret3")); for (int i = 0; i < 10; i++) { assertEquals(1, encoder3.encodeBoolean(false)[0]); } for (int i = 0; i < 10; i++) { assertEquals(0, encoder3.encodeBoolean(true)[0]); } } @Test public void testLongitudinalReportingInsecureEncoder_setSeedCorrectly() throws Exception { final int n = 10000; final double f = 0.35; final double expectedTrueSum = n * f; final double valueRange = 5 * Math.sqrt(n * f * (1 - f)); int trueSum = 0; for (int i = 0; i < n; i++) { final LongitudinalReportingConfig config = new LongitudinalReportingConfig( "encoder" + i, // encoderId f, // probabilityF 0, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder = LongitudinalReportingEncoder.createInsecureEncoderForTest(config); boolean encodedFalse = encoder.encodeBoolean(false)[0] > 0; if (encodedFalse) { trueSum += 1; } } // Total number of true(s) should be around the mean (10000 * 0.35) assertThat((double) trueSum).isLessThan(expectedTrueSum + valueRange); assertThat((double) trueSum).isAtLeast(expectedTrueSum - valueRange); } @Test public void testLongitudinalReportingEncoder_basicPRRTest() throws Exception { // Should always return original value when p = 0 for (int i = 0; i < 10; i++) { for (int j = 0; j < 10; j++) { final LongitudinalReportingConfig config1 = new LongitudinalReportingConfig( "Foo" + i, // encoderId 0, // probabilityF 0, // probabilityP 0); // probabilityQ final LongitudinalReportingEncoder encoder1 = LongitudinalReportingEncoder.createEncoder( config1, makeTestingUserSecret("encoder" + j)); assertEquals(0, encoder1.encodeBoolean(false)[0]); assertEquals(0, encoder1.encodeBoolean(false)[0]); assertEquals(0, encoder1.encodeBoolean(false)[0]); assertEquals(0, encoder1.encodeBoolean(false)[0]); assertEquals(0, encoder1.encodeBoolean(false)[0]); assertEquals(1, encoder1.encodeBoolean(true)[0]); assertEquals(1, encoder1.encodeBoolean(true)[0]); assertEquals(1, encoder1.encodeBoolean(true)[0]); assertEquals(1, encoder1.encodeBoolean(true)[0]); assertEquals(1, encoder1.encodeBoolean(true)[0]); } } // Should always return false when p = 1, q = 0 for (int i = 0; i < 10; i++) { for (int j = 0; j < 10; j++) { final LongitudinalReportingConfig config2 = new LongitudinalReportingConfig( "Foo" + i, // encoderId 0, // probabilityF 1, // probabilityP 0); // probabilityQ final LongitudinalReportingEncoder encoder2 = LongitudinalReportingEncoder.createEncoder( config2, makeTestingUserSecret("encoder" + j)); assertEquals(0, encoder2.encodeBoolean(false)[0]); assertEquals(0, encoder2.encodeBoolean(false)[0]); assertEquals(0, encoder2.encodeBoolean(false)[0]); assertEquals(0, encoder2.encodeBoolean(false)[0]); assertEquals(0, encoder2.encodeBoolean(false)[0]); assertEquals(0, encoder2.encodeBoolean(true)[0]); assertEquals(0, encoder2.encodeBoolean(true)[0]); assertEquals(0, encoder2.encodeBoolean(true)[0]); assertEquals(0, encoder2.encodeBoolean(true)[0]); assertEquals(0, encoder2.encodeBoolean(true)[0]); } } // Should always return true when p = 1, q = 1 for (int i = 0; i < 10; i++) { for (int j = 0; j < 10; j++) { final LongitudinalReportingConfig config3 = new LongitudinalReportingConfig( "Foo" + i, // encoderId 0, // probabilityF 1, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder3 = LongitudinalReportingEncoder.createEncoder( config3, makeTestingUserSecret("encoder" + j)); assertEquals(1, encoder3.encodeBoolean(false)[0]); assertEquals(1, encoder3.encodeBoolean(false)[0]); assertEquals(1, encoder3.encodeBoolean(false)[0]); assertEquals(1, encoder3.encodeBoolean(false)[0]); assertEquals(1, encoder3.encodeBoolean(false)[0]); assertEquals(1, encoder3.encodeBoolean(true)[0]); assertEquals(1, encoder3.encodeBoolean(true)[0]); assertEquals(1, encoder3.encodeBoolean(true)[0]); assertEquals(1, encoder3.encodeBoolean(true)[0]); assertEquals(1, encoder3.encodeBoolean(true)[0]); } } // PRR should return different value when encoder id is changed boolean hasFalseResult1 = false; boolean hasTrueResult1 = false; for (int i = 0; i < 50; i++) { boolean firstResult = false; for (int j = 0; j < 10; j++) { final LongitudinalReportingConfig config4 = new LongitudinalReportingConfig( "Foo" + i, // encoderId 0, // probabilityF 1, // probabilityP 0.5); // probabilityQ final LongitudinalReportingEncoder encoder4 = LongitudinalReportingEncoder.createEncoder( config4, makeTestingUserSecret("encoder4")); boolean encodedFalse = encoder4.encodeBoolean(false)[0] > 0; boolean encodedTrue = encoder4.encodeBoolean(true)[0] > 0; // PRR should always give the same value when all parameters are the same assertEquals(encodedTrue, encodedFalse); if (j == 0) { firstResult = encodedTrue; } else { assertEquals(firstResult, encodedTrue); } if (encodedTrue) { hasTrueResult1 = true; } else { hasFalseResult1 = true; } } } // Ensure it has both true and false results when encoder id is different assertTrue(hasTrueResult1); assertTrue(hasFalseResult1); // PRR should give different value when secret is changed boolean hasFalseResult2 = false; boolean hasTrueResult2 = false; for (int i = 0; i < 50; i++) { boolean firstResult = false; for (int j = 0; j < 10; j++) { final LongitudinalReportingConfig config5 = new LongitudinalReportingConfig( "Foo", // encoderId 0, // probabilityF 1, // probabilityP 0.5); // probabilityQ final LongitudinalReportingEncoder encoder5 = LongitudinalReportingEncoder.createEncoder( config5, makeTestingUserSecret("encoder" + i)); boolean encodedFalse = encoder5.encodeBoolean(false)[0] > 0; boolean encodedTrue = encoder5.encodeBoolean(true)[0] > 0; // PRR should always give the same value when parameters are the same assertEquals(encodedTrue, encodedFalse); if (j == 0) { firstResult = encodedTrue; } else { assertEquals(firstResult, encodedTrue); } if (encodedTrue) { hasTrueResult2 = true; } else { hasFalseResult2 = true; } } } // Ensure it has both true and false results when encoder id is different assertTrue(hasTrueResult2); assertTrue(hasFalseResult2); // Confirm if PRR randomizer is working correctly final int n1 = 1000; final double p1 = 0.8; final double expectedTrueSum1 = n1 * p1; final double valueRange1 = 5 * Math.sqrt(n1 * p1 * (1 - p1)); int trueSum1 = 0; for (int i = 0; i < n1; i++) { final LongitudinalReportingConfig config6 = new LongitudinalReportingConfig( "Foo", // encoderId 0, // probabilityF p1, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder6 = LongitudinalReportingEncoder.createEncoder( config6, makeTestingUserSecret("encoder" + i)); boolean encodedFalse = encoder6.encodeBoolean(false)[0] > 0; if (encodedFalse) { trueSum1 += 1; } } // Total number of true(s) should be around the mean (1000 * 0.8) assertThat((double) trueSum1).isLessThan(expectedTrueSum1 + valueRange1); assertThat((double) trueSum1).isAtLeast(expectedTrueSum1 - valueRange1); // Confirm if PRR randomizer is working correctly final int n2 = 1000; final double p2 = 0.2; final double expectedTrueSum2 = n2 * p2; final double valueRange2 = 5 * Math.sqrt(n2 * p2 * (1 - p2)); int trueSum2 = 0; for (int i = 0; i < n2; i++) { final LongitudinalReportingConfig config7 = new LongitudinalReportingConfig( "Foo", // encoderId 0, // probabilityF p2, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder7 = LongitudinalReportingEncoder.createEncoder( config7, makeTestingUserSecret("encoder" + i)); boolean encodedFalse = encoder7.encodeBoolean(false)[0] > 0; if (encodedFalse) { trueSum2 += 1; } } // Total number of true(s) should be around the mean (1000 * 0.2) assertThat((double) trueSum2).isLessThan(expectedTrueSum2 + valueRange2); assertThat((double) trueSum2).isAtLeast(expectedTrueSum2 - valueRange2); } @Test public void testLongitudinalReportingEncoder_basicIRRwithPRRTest() throws Exception { // Verify PRR result will run IRR boolean hasFalseResult1 = false; boolean hasTrueResult1 = false; for (int i = 0; i < 50; i++) { final LongitudinalReportingConfig config1 = new LongitudinalReportingConfig( "Foo", // encoderId 0.5, // probabilityF 1, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder1 = LongitudinalReportingEncoder.createEncoder( config1, makeTestingUserSecret("encoder1")); if (encoder1.encodeBoolean(false)[0] > 0) { hasTrueResult1 = true; } else { hasFalseResult1 = true; } } assertTrue(hasTrueResult1); assertTrue(hasFalseResult1); // When secret is different, some device should use PRR result, some should use IRR result boolean hasFalseResult2 = false; boolean hasTrueResult2 = false; for (int i = 0; i < 50; i++) { final LongitudinalReportingConfig config2 = new LongitudinalReportingConfig( "Foo", // encoderId 1, // probabilityF 0.5, // probabilityP 1); // probabilityQ final LongitudinalReportingEncoder encoder2 = LongitudinalReportingEncoder.createEncoder( config2, makeTestingUserSecret("encoder" + i)); if (encoder2.encodeBoolean(false)[0] > 0) { hasTrueResult2 = true; } else { hasFalseResult2 = true; } } assertTrue(hasTrueResult2); assertTrue(hasFalseResult2); } @Test public void testLongTermRandomizedResult() throws Exception { // Verify getLongTermRandomizedResult can return expected result when parameters are fixed. final boolean[] expectedResult = new boolean[]{true, false, true, true, true, false, false, false, true, false, false, false, false, true, true, true, true, false, true, true, true, true, false, true, true}; for (int i = 0; i < 5; i++) { for (int j = 0; j < 5; j++) { boolean result = LongitudinalReportingEncoder.getLongTermRandomizedResult(0.5, true, makeTestingUserSecret("secret" + i), "encoder" + j); assertEquals(expectedResult[i * 5 + j], result); } } } 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(); } }