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Create utils class to standardize implementation on hex digest of bytes.

Browse Source 
Test: atest AppIntegrityManagerServiceImplTest
Test: atest IntegrityUtilsTest
Change-Id: I019ed45fffd6ab2599e49f6e370b4f2a8f175bfb
This commit is contained in:
Song Pan
2019-12-24 12:09:15 +00:00
parent dbc4e9c468
commit 068e09a112
3 changed files with 144 additions and 11 deletions
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15
services/core/java/com/android/server/integrity/AppIntegrityManagerServiceImpl.java
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@@ -25,6 +25,8 @@ import static android.content.integrity.AppIntegrityManager.STATUS_FAILURE;
import static android.content.integrity.AppIntegrityManager.STATUS_SUCCESS;
import static android.content.pm.PackageManager.EXTRA_VERIFICATION_ID;
import static com.android.server.integrity.IntegrityUtils.getHexDigest;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.BroadcastReceiver;
@@ -331,7 +333,7 @@ public class AppIntegrityManagerServiceImpl extends IAppIntegrityManager.Stub {
try {
MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
byte[] hashBytes = messageDigest.digest(packageName.getBytes(StandardCharsets.UTF_8));
return toHexString(hashBytes);
return getHexDigest(hashBytes);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException("SHA-256 algorithm not found", e);
}
@@ -425,21 +427,12 @@ public class AppIntegrityManagerServiceImpl extends IAppIntegrityManager.Stub {
try {
MessageDigest digest = MessageDigest.getInstance("SHA-256");
byte[] publicKey = digest.digest(certificate.getEncoded());
return toHexString(publicKey);
return getHexDigest(publicKey);
} catch (NoSuchAlgorithmException | CertificateEncodingException e) {
throw new IllegalArgumentException("Error error computing fingerprint", e);
}
}
private static String toHexString(byte[] bytes) {
// each byte is represented by two hex chars
StringBuffer hexString = new StringBuffer(bytes.length * 2);
for (int i = 0; i < bytes.length; i++) {
hexString.append(String.format("%02X", bytes[i]));
}
return new String(hexString);
}
private PackageInfo getPackageArchiveInfo(Uri dataUri) {
File installationPath = getInstallationPath(dataUri);
if (installationPath == null) {

79
services/core/java/com/android/server/integrity/IntegrityUtils.java Normal file
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@@ -0,0 +1,79 @@
/*
* Copyright (C) 2019 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 com.android.server.integrity;
import static com.android.internal.util.Preconditions.checkArgument;
/** Utils class for simple operations used in integrity module. */
public class IntegrityUtils {
private static final char[] HEX_CHARS = "0123456789ABCDEF".toCharArray();
/**
* Obtain the raw bytes from hex encoded string.
*
* @throws IllegalArgumentException if {@code hexDigest} is not a valid hex encoding of some
* bytes
*/
public static byte[] getBytesFromHexDigest(String hexDigest) {
checkArgument(
hexDigest.length() % 2 == 0,
"Invalid hex encoding " + hexDigest + ": must have even length");
byte[] rawBytes = new byte[hexDigest.length() / 2];
for (int i = 0; i < rawBytes.length; i++) {
int upperNibble = hexDigest.charAt(2 * i);
int lowerNibble = hexDigest.charAt(2 * i + 1);
rawBytes[i] = (byte) ((hexToDec(upperNibble) << 4) | hexToDec(lowerNibble));
}
return rawBytes;
}
/** Obtain hex encoded string from raw bytes. */
public static String getHexDigest(byte[] rawBytes) {
char[] hexChars = new char[rawBytes.length * 2];
for (int i = 0; i < rawBytes.length; i++) {
int upperNibble = (rawBytes[i] >>> 4) & 0xF;
int lowerNibble = rawBytes[i] & 0xF;
hexChars[i * 2] = decToHex(upperNibble);
hexChars[i * 2 + 1] = decToHex(lowerNibble);
}
return new String(hexChars);
}
private static int hexToDec(int hexChar) {
if (hexChar >= '0' && hexChar <= '9') {
return hexChar - '0';
}
if (hexChar >= 'a' && hexChar <= 'f') {
return hexChar - 'a' + 10;
}
if (hexChar >= 'A' && hexChar <= 'F') {
return hexChar - 'A' + 10;
}
throw new IllegalArgumentException("Invalid hex char " + hexChar);
}
private static char decToHex(int dec) {
if (dec >= 0 && dec < HEX_CHARS.length) {
return HEX_CHARS[dec];
}
throw new IllegalArgumentException("Invalid dec value to be converted to hex digit " + dec);
}
}

61
services/tests/servicestests/src/com/android/server/integrity/IntegrityUtilsTest.java Normal file
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@@ -0,0 +1,61 @@
/*
* Copyright (C) 2019 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 com.android.server.integrity;
import static com.android.server.integrity.IntegrityUtils.getBytesFromHexDigest;
import static com.android.server.integrity.IntegrityUtils.getHexDigest;
import static com.android.server.testutils.TestUtils.assertExpectException;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import androidx.test.runner.AndroidJUnit4;
import org.junit.Test;
import org.junit.runner.RunWith;
/** Unit test for {@link com.android.server.integrity.IntegrityUtils} */
@RunWith(AndroidJUnit4.class)
public class IntegrityUtilsTest {
private static final String HEX_DIGEST = "1234567890ABCDEF";
private static final byte[] BYTES =
new byte[] {0x12, 0x34, 0x56, 0x78, (byte) 0x90, (byte) 0xAB, (byte) 0xCD, (byte) 0xEF};
@Test
public void testGetBytesFromHexDigest() {
assertArrayEquals(BYTES, getBytesFromHexDigest(HEX_DIGEST));
}
@Test
public void testGetHexDigest() {
assertEquals(HEX_DIGEST, getHexDigest(BYTES));
}
@Test
public void testInvalidHexDigest() {
assertExpectException(
IllegalArgumentException.class,
"must have even length",
() -> getBytesFromHexDigest("ABC"));
assertExpectException(
IllegalArgumentException.class,
"Invalid hex char",
() -> getBytesFromHexDigest("GH"));
}
}