Author: schultz
Date: Tue Nov 27 00:40:14 2018
New Revision: 1847504
URL: http://svn.apache.org/viewvc?rev=1847504&view=rev
Log:
Simplify createEncryptionManager method.
Document magic numbers in GCMEncryptionManager.
Add (disabled) ECB implementation, for completeness.
Add unit-test to ensure that ECB mode is not supported.
Modified:
tomcat/trunk/java/org/apache/catalina/tribes/group/interceptors/EncryptInterceptor.java
tomcat/trunk/test/org/apache/catalina/tribes/group/interceptors/TestEncryptInterceptor.java
Modified:
tomcat/trunk/java/org/apache/catalina/tribes/group/interceptors/EncryptInterceptor.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/tribes/group/interceptors/EncryptInterceptor.java?rev=1847504&r1=1847503&r2=1847504&view=diff
==============================================================================
---
tomcat/trunk/java/org/apache/catalina/tribes/group/interceptors/EncryptInterceptor.java
(original)
+++
tomcat/trunk/java/org/apache/catalina/tribes/group/interceptors/EncryptInterceptor.java
Tue Nov 27 00:40:14 2018
@@ -328,20 +328,19 @@ public class EncryptInterceptor extends
algorithmMode = "CBC";
}
- // Note: ECB is not an appropriate mode for secure communications.
if("GCM".equalsIgnoreCase(algorithmMode))
return new GCMEncryptionManager(algorithm, new
SecretKeySpec(encryptionKey, algorithmName), providerName);
-
- if(!("CBC".equalsIgnoreCase(algorithmMode)
+ else if("CBC".equalsIgnoreCase(algorithmMode)
|| "OFB".equalsIgnoreCase(algorithmMode)
- || "CFB".equalsIgnoreCase(algorithmMode)))
+ || "CFB".equalsIgnoreCase(algorithmMode))
+ return new BaseEncryptionManager(algorithm,
+ new SecretKeySpec(encryptionKey, algorithmName),
+ providerName);
+// else if("ECB".equalsIgnoreCase(algorithmMode)) {
+ // Note: ECB is not an appropriate mode for secure communications.
+// return new ECBEncryptionManager(algorithm, new
SecretKeySpec(encryptionKey, algorithmName), providerName);
+ else
throw new
IllegalArgumentException(sm.getString("encryptInterceptor.algorithm.unsupported-mode",
algorithmMode));
-
- BaseEncryptionManager mgr = new BaseEncryptionManager(algorithm,
- new SecretKeySpec(encryptionKey, algorithmName),
- providerName);
-
- return mgr;
}
private static class BaseEncryptionManager {
@@ -406,8 +405,9 @@ public class EncryptInterceptor extends
}
/**
- * Gets the size of the initialization vector for the cipher being
used.
- * The IV size is often, but not always, the block size for the cipher.
+ * Gets the size, in bytes, of the initialization vector for the
+ * cipher being used. The IV size is often, but not always, the block
+ * size for the cipher.
*
* @return The size of the initialization vector for this algorithm.
*/
@@ -550,6 +550,25 @@ public class EncryptInterceptor extends
}
}
+ /**
+ * Implements an EncryptionManager for using GCM block cipher modes.
+ *
+ * GCM works a little differently than some of the other block cipher modes
+ * supported by EncryptInterceptor. First of all, it requires a different
+ * kind of AlgorithmParameterSpec object to be used, and second, it
+ * requires a slightly different initialization vector and something called
+ * an "authentication tag".
+ *
+ * The choice of IV length can be somewhat arbitrary, but there is
consensus
+ * that 96-bit (12-byte) IVs for GCM are the best trade-off between
security
+ * and performance. For other block cipher modes, IV length is the same as
+ * the block size.
+ *
+ * The "authentication tag" is a computed authentication value based upon
+ * the message and the encryption process. GCM defines these tags as the
+ * number of bits to use for the authentication tag, and it's clear that
+ * the highest number of bits supported 128-bit provide the best security.
+ */
private static class GCMEncryptionManager extends BaseEncryptionManager
{
public GCMEncryptionManager(String algorithm, SecretKeySpec secretKey,
String providerName)
@@ -559,12 +578,39 @@ public class EncryptInterceptor extends
@Override
protected int getIVSize() {
- return 12;
+ return 12; // See class javadoc for explanation of this magic
number (12)
}
@Override
protected AlgorithmParameterSpec generateIV(byte[] bytes, int offset,
int length) {
+ // See class javadoc for explanation of this magic number (128)
return new GCMParameterSpec(128, bytes, offset, length);
}
}
+
+ @SuppressWarnings("unused")
+ private static class ECBEncryptionManager extends BaseEncryptionManager
+ {
+ public ECBEncryptionManager(String algorithm, SecretKeySpec secretKey,
String providerName)
+ throws NoSuchAlgorithmException, NoSuchPaddingException,
NoSuchProviderException {
+ super(algorithm, secretKey, providerName);
+ }
+
+ private static final byte[] EMPTY_IV = new byte[0];
+
+ @Override
+ protected int getIVSize() {
+ return 0;
+ }
+
+ @Override
+ protected byte[] generateIVBytes() {
+ return EMPTY_IV;
+ }
+
+ @Override
+ protected AlgorithmParameterSpec generateIV(byte[] bytes, int offset,
int length) {
+ return null;
+ }
+ }
}
Modified:
tomcat/trunk/test/org/apache/catalina/tribes/group/interceptors/TestEncryptInterceptor.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/test/org/apache/catalina/tribes/group/interceptors/TestEncryptInterceptor.java?rev=1847504&r1=1847503&r2=1847504&view=diff
==============================================================================
---
tomcat/trunk/test/org/apache/catalina/tribes/group/interceptors/TestEncryptInterceptor.java
(original)
+++
tomcat/trunk/test/org/apache/catalina/tribes/group/interceptors/TestEncryptInterceptor.java
Tue Nov 27 00:40:14 2018
@@ -269,6 +269,19 @@ public class TestEncryptInterceptor {
}
@Test
+ public void testIllegalECB() throws Exception {
+ try {
+ src.setEncryptionAlgorithm("AES/ECB/PKCS5Padding");
+ src.start(Channel.SND_TX_SEQ);
+
+ // start() should trigger IllegalArgumentException
+ Assert.fail("ECB mode is not being refused");
+ } catch (IllegalArgumentException iae) {
+ // Expected
+ }
+ }
+
+ @Test
public void testViaFile() throws Exception {
src.start(Channel.SND_TX_SEQ);
src.setNext(new ValueCaptureInterceptor());
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