在Android 4.2加密错误 [英] Encryption error on Android 4.2
问题描述
下面code是工作在Android上的一切，除了版本的最新4.2
The following code is working on all the versions of android except the latest 4.2
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
* Util class to perform encryption/decryption over strings. <br/>
*/
public final class UtilsEncryption
{
/** The logging TAG */
private static final String TAG = UtilsEncryption.class.getName();
/** */
private static final String KEY = "some_encryption_key";
/**
* Avoid instantiation. <br/>
*/
private UtilsEncryption()
{
}
/** The HEX characters */
private final static String HEX = "0123456789ABCDEF";
/**
* Encrypt a given string. <br/>
*
* @param the string to encrypt
* @return the encrypted string in HEX
*/
public static String encrypt( String cleartext )
{
try
{
byte[] result = process( Cipher.ENCRYPT_MODE, cleartext.getBytes() );
return toHex( result );
}
catch ( Exception e )
{
System.out.println( TAG + ":encrypt:" + e.getMessage() );
}
return null;
}
/**
* Decrypt a HEX encrypted string. <br/>
*
* @param the HEX string to decrypt
* @return the decrypted string
*/
public static String decrypt( String encrypted )
{
try
{
byte[] enc = fromHex( encrypted );
byte[] result = process( Cipher.DECRYPT_MODE, enc );
return new String( result );
}
catch ( Exception e )
{
System.out.println( TAG + ":decrypt:" + e.getMessage() );
}
return null;
}
/**
* Get the raw encryption key. <br/>
*
* @param the seed key
* @return the raw key
* @throws NoSuchAlgorithmException
*/
private static byte[] getRawKey()
throws NoSuchAlgorithmException
{
KeyGenerator kgen = KeyGenerator.getInstance( "AES" );
SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG" );
sr.setSeed( KEY.getBytes() );
kgen.init( 128, sr );
SecretKey skey = kgen.generateKey();
return skey.getEncoded();
}
/**
* Process the given input with the provided mode. <br/>
*
* @param the cipher mode
* @param the value to process
* @return the processed value as byte[]
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
*/
private static byte[] process( int mode, byte[] value )
throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException,
NoSuchPaddingException
{
SecretKeySpec skeySpec = new SecretKeySpec( getRawKey(), "AES" );
Cipher cipher = Cipher.getInstance( "AES" );
cipher.init( mode, skeySpec );
byte[] encrypted = cipher.doFinal( value );
return encrypted;
}
/**
* Decode an HEX encoded string into a byte[]. <br/>
*
* @param the HEX string value
* @return the decoded byte[]
*/
protected static byte[] fromHex( String value )
{
int len = value.length() / 2;
byte[] result = new byte[len];
for ( int i = 0; i < len; i++ )
{
result[i] = Integer.valueOf( value.substring( 2 * i, 2 * i + 2 ), 16 ).byteValue();
}
return result;
}
/**
* Encode a byte[] into an HEX string. <br/>
*
* @param the byte[] value
* @return the HEX encoded string
*/
protected static String toHex( byte[] value )
{
if ( value == null )
{
return "";
}
StringBuffer result = new StringBuffer( 2 * value.length );
for ( int i = 0; i < value.length; i++ )
{
byte b = value[i];
result.append( HEX.charAt( ( b >> 4 ) & 0x0f ) );
result.append( HEX.charAt( b & 0x0f ) );
}
return result.toString();
}
}
下面是我创建重现该错误的小单元测试
Here's a small unit test that i've created to reproduce the error
import junit.framework.TestCase;
public class UtilsEncryptionTest
extends TestCase
{
/** A random string */
private static String ORIGINAL = "some string to test";
/**
* The HEX value corresponds to ORIGINAL. <br/>
* If you change ORIGINAL, calculate the new value on one of this sites:
* <ul>
* <li>http://www.string-functions.com/string-hex.aspx</li>
* <li>http://www.yellowpipe.com/yis/tools/encrypter/index.php</li>
* <li>http://www.convertstring.com/EncodeDecode/HexEncode</li>
* </ul>
*/
private static String HEX = "736F6D6520737472696E6720746F2074657374";
public void testToHex()
{
String hexString = UtilsEncryption.toHex( ORIGINAL.getBytes() );
assertNotNull( "The HEX string should not be null", hexString );
assertTrue( "The HEX string should not be empty", hexString.length() > 0 );
assertEquals( "The HEX string was not encoded correctly", HEX, hexString );
}
public void testFromHex()
{
byte[] stringBytes = UtilsEncryption.fromHex( HEX );
assertNotNull( "The HEX string should not be null", stringBytes );
assertTrue( "The HEX string should not be empty", stringBytes.length > 0 );
assertEquals( "The HEX string was not encoded correctly", ORIGINAL, new String( stringBytes ) );
}
public void testWholeProcess()
{
String encrypted = UtilsEncryption.encrypt( ORIGINAL );
assertNotNull( "The encrypted result should not be null", encrypted );
assertTrue( "The encrypted result should not be empty", encrypted.length() > 0 );
String decrypted = UtilsEncryption.decrypt( encrypted );
assertNotNull( "The decrypted result should not be null", decrypted );
assertTrue( "The decrypted result should not be empty", decrypted.length() > 0 );
assertEquals( "Something went wrong", ORIGINAL, decrypted );
}
}
该行抛出的例外是：
byte[] encrypted = cipher.doFinal( value );
完整的堆栈跟踪是：
The full stack trace is:
W/<package>.UtilsEncryption:decrypt(16414): pad block corrupted
W/System.err(16414): javax.crypto.BadPaddingException: pad block corrupted
W/System.err(16414): at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(BaseBlockCipher.java:709)
W/System.err(16414): at javax.crypto.Cipher.doFinal(Cipher.java:1111)
W/System.err(16414): at <package>.UtilsEncryption.process(UtilsEncryption.java:117)
W/System.err(16414): at <package>.UtilsEncryption.decrypt(UtilsEncryption.java:69)
W/System.err(16414): at <package>.UtilsEncryptionTest.testWholeProcess(UtilsEncryptionTest.java:74)
W/System.err(16414): at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err(16414): at java.lang.reflect.Method.invoke(Method.java:511)
W/System.err(16414): at junit.framework.TestCase.runTest(TestCase.java:168)
W/System.err(16414): at junit.framework.TestCase.runBare(TestCase.java:134)
W/System.err(16414): at junit.framework.TestResult$1.protect(TestResult.java:115)
W/System.err(16414): at junit.framework.TestResult.runProtected(TestResult.java:133)
D/elapsed ( 588): 14808
W/System.err(16414): at junit.framework.TestResult.run(TestResult.java:118)
W/System.err(16414): at junit.framework.TestCase.run(TestCase.java:124)
W/System.err(16414): at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:190)
W/System.err(16414): at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:175)
W/System.err(16414): at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:555)
W/System.err(16414): at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1661)
没有任何人有什么可能发生的线索？ 是否有人知道任何引用的类在Android 4.2重大更改吗？
Does anybody have a clue of what might be happening ? Is anybody aware of a breaking change on android 4.2 in any of the referenced classes?
多谢
推荐答案
从的 Android的杰利贝恩页：
修改的SecureRandom和Cipher.RSA的默认实现来使用OpenSSL
Modified the default implementations of SecureRandom and Cipher.RSA to use OpenSSL
他们改变了默认提供的SecureRandom 来使用，而不是previous加密提供商OpenSSL的。
They changed the default provider for SecureRandom to use OpenSSL instead of the previous Crypto provider.
下面code将产生pre-的Android 4.2和两个不同的输出的Android 4.2：
The following code will produce two different outputs on pre-Android 4.2 and Android 4.2:
SecureRandom rand = SecureRandom.getInstance("SHA1PRNG");
Log.i(TAG, "rand.getProvider(): " + rand.getProvider().getName());
在pre-4.2的设备：
On pre-4.2 devices:
rand.getProvider：加密
rand.getProvider: Crypto
在4.2设备：
rand.getProvider：AndroidOpenSSL
rand.getProvider: AndroidOpenSSL
幸运的是，很容易恢复到原来的行为：
Fortunately, it's easy to revert to the old behavior:
SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG", "Crypto" );
当然，这是危险的被调用 SecureRandom.setSeed 在所有的光的<一个href="http://developer.android.com/reference/java/security/SecureRandom.html#getInstance%28java.lang.String,%20java.lang.String%29"相对=nofollow>的Javadoc 其状态：
To be sure, it's dangerous to be calling SecureRandom.setSeed at all in light of the Javadocs which state:
播种SecureRandom的可能是不安全的。
Seeding SecureRandom may be insecure
种子是用来引导随机数生成的字节数组。以产生加密的安全随机数，无论是种子和算法必须是安全的。
A seed is an array of bytes used to bootstrap random number generation. To produce cryptographically secure random numbers, both the seed and the algorithm must be secure.
在默认情况下，这个类的实例将产生使用内部信息源，例如/ dev / urandom的初始种子。这个种子是联合国predictable和恰当的安全使用。
By default, instances of this class will generate an initial seed using an internal entropy source, such as /dev/urandom. This seed is unpredictable and appropriate for secure use.
您可以替换明确与种子的构造函数或调用过setSeed（byte []的）已产生的任何随机数之前指定的初始种子。指定一个固定的种子会导致实例返回数字的predictable序列。 这可能是用于测试，但它并不适用于安全使用。
You may alternatively specify the initial seed explicitly with the seeded constructor or by calling setSeed(byte[]) before any random numbers have been generated. Specifying a fixed seed will cause the instance to return a predictable sequence of numbers. This may be useful for testing but it is not appropriate for secure use.
不过，对于编写单元测试，因为你正在做的，使用过setSeed 可能会好起来的。
However, for writing unit tests, as you are doing, using setSeed may be okay.
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